Inspection equipment

Abstract

The objective is to provide an inspection device that can identify abnormalities that are difficult for inspectors to detect visually, using a simpler configuration while maintaining a certain level of accuracy. [Solution] An inspection device for detecting defects in a solar cell string, which is part of a solar cell module, in which solar cells and wiring members are connected using an adhesive, comprising: an imaging unit and a first illumination unit, wherein the first illumination unit is capable of irradiating the solar cell string with first light having a wavelength of 360 nm to 420 nm, the imaging unit is capable of performing a first imaging operation to photograph the solar cell string when irradiated with the first light, and the inspection device comprises a detection unit that detects a first defect based on image data created by the first imaging operation.

Description

Technical Field

[0001] The present invention relates to an inspection device for detecting defects in solar cell strings.

Background Art

[0002] Conventionally, a so-called shingled solar cell string formed by arranging end edges of adjacent solar cells in an overlapping manner and connecting electrode portions of the adjacent solar cells to each other is known.

[0003] Some of such solar cell strings employ a so-called back-contact solar cell in which an electrode portion is formed only on the back surface side. A solar cell module employing this solar cell string has a uniform appearance across the entire light-receiving surface. For this reason, when an appearance abnormality occurs in a solar cell, such as when some foreign matter mixes in during the manufacturing process of the solar cell, there is a problem that the occurring abnormality becomes extremely noticeable. That is, solar cell modules have a narrow allowable range for non-defective abnormalities, and there are cases where even an appearance abnormality that would not be a problem in other solar cell modules becomes a problem.

[0004] Patent Document 1 discloses a solar cell inspection device that identifies black spot candidate regions, which are candidates for black spots in solar cells, by image analysis. According to this inspection device, black spots that are difficult to detect by visual inspection of an inspector can be extracted with high accuracy.

Prior Art Literature

Patent Literature

[0005]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0006] Incidentally, in addition to the black spots mentioned above that occur due to errors or unforeseen circumstances during the manufacturing of solar cells, solar cell strings can also experience abnormalities due to errors or unforeseen circumstances during the connection of solar cells to each other or to the connection of solar cells to wiring. Such abnormalities include, for example, the conductive paste (adhesive) used to connect the electrodes of solar cells overflowing onto the surface of the solar cells. Another example is the flux (soldering accelerator) used for soldering adhering to places where it should not be, such as the surface of the solar cells. Furthermore, abnormalities caused by flux are difficult for inspectors to detect visually. Here, conventional inspection equipment had room for improvement in its ability to identify various types of abnormalities in solar cell strings that are difficult for inspectors to detect visually, while maintaining a certain level of accuracy with a simple configuration.

[0007] Therefore, the object of the present invention is to provide an inspection device that can identify abnormalities that are difficult for inspectors to detect visually, with a simpler configuration and while maintaining a certain level of accuracy. [Means for solving the problem]

[0008] In order to solve the above problems, the inventors conducted diligent research and found that by irradiating with light of a specific wavelength while taking photographs, it is possible to highlight abnormalities that are difficult to distinguish by visual inspection or by irradiating with light of other wavelength ranges while taking photographs. Specifically, it was found that by irradiating with light with a wavelength of 360 nm to 420 nm while taking photographs, it is possible to highlight and image specific abnormalities such as fingerprint stains caused by a mixture of flux and sebum resulting from a person touching a solar cell with flux-covered hands. One aspect of the present invention, provided based on the above-mentioned findings, is an inspection device for detecting defects in a solar cell string, which is part of a solar cell module, in which solar cells and wiring members are connected using an adhesive, and the inspection device comprises an imaging unit and a first illumination unit, wherein the first illumination unit is capable of irradiating the solar cell string with first light having a wavelength of 360 nm or more and 420 nm or less, the imaging unit is capable of performing a first imaging operation to photograph the solar cell string in the state irradiated with the first light, and the inspection device comprises a detection unit that detects a first defect based on image data created by the first imaging operation.

[0009] According to this method, it is possible to create image data that highlights anomalies that are difficult to distinguish from the surrounding area by visual inspection, without using various equipment or performing complex processing. As a result, anomalies that are difficult to detect by visual inspection can be detected with a simple configuration and high accuracy.

[0010] A preferred aspect is that the first defect is caused by an oxide decomposing agent containing oil.

[0011] This method accurately detects contamination (abnormalities) that are difficult to see with the naked eye, such as contamination caused by workers touching solar cells with flux-covered hands.

[0012] A preferred aspect is that the adhesive contains components similar to oxide decomposing agents that may cause the first defect.

[0013] Under these circumstances, defects occurring in solar cell strings using such adhesives to connect wiring components can be accurately detected.

[0014] A preferred configuration is that the first illumination unit irradiates the solar cell string with light from a direction inclined at an angle of 0 to 45 degrees with respect to the imaging axis of the imaging unit.

[0015] Under these circumstances, it becomes possible to acquire image data that more clearly highlights the areas where abnormalities have occurred.

[0016] A preferred configuration is one in which the first illumination unit has a first light source unit that emits light, the solar cell string is arranged to extend in a direction perpendicular to the imaging axis of the imaging unit, and the first light source unit extends linearly in the direction of the extension of the solar cell string.

[0017] In this configuration, it becomes possible to illuminate the solar cell string, which is the object being inspected, with light in a way that is less shadowed and less uneven, and to acquire image data that makes it easier to detect abnormalities.

[0018] A preferred configuration includes a second illumination unit capable of irradiating the solar cell string with a second light that is visible light and has a wavelength of 600 nm or more, an imaging unit that performs a second imaging operation to photograph the solar cell string when it is irradiated with the second light, and a detection unit that detects a second defect different from the first defect based on the image data created by the second imaging operation.

[0019] Under these circumstances, a wider variety of anomalies can be accurately detected.

[0020] In the above-described manner, both the first and second shooting operations create grayscale images, and it is more preferable that the first defect, when represented by the image data created by the first shooting operation, has a greater contrast in density with adjacent parts than when represented by the image data created by the second shooting operation.

[0021] This favorable configuration allows for more accurate detection of both the first and second defects.

[0022] In the aspect described above, it is more preferable that the second defect includes a first missing portion which is a missing portion penetrating any part of the solar cell string and a second missing portion which is a missing portion not penetrating any part of the solar cell string, and the detection is performed by identifying whether the defect is the first missing portion or the second missing portion.

[0023] According to this aspect, it is possible to identify and detect the first missing portion and the second missing portion with a simple configuration.

[0024] In the aspect described above, it is more preferable that the apparatus comprises an image base forming unit, the second imaging operation is performed by disposing the solar cell string between the imaging unit and the image base forming unit, and at least a part of a surface of the image base forming unit on the solar cell string side exhibits substantially the same color as the second light.

[0025] According to this aspect, the second defect can be detected more accurately.

[0026] As long as the aspects described above are included in the technical scope of the present invention, the aspects can be mutually dependent, cite partial configurations, or replace partial configurations with each other.

Effects of the Invention

[0027] The present invention can provide an inspection apparatus capable of identifying an abnormality that is difficult to be found visually by an inspector with a simple configuration while exhibiting accuracy of a certain level or higher.

Brief Description of Drawings

[0028] [Figure 1] It is a block diagram showing an inspection apparatus according to an embodiment of the present invention. [Figure 2] It is an explanatory diagram schematically showing the imaging unit in FIG. 1. [Figure 3] It is a plan view schematically showing the imaging unit in FIG. 2. [Figure 4] It is a plan view schematically showing a solar cell string that is an inspection object of the inspection apparatus in FIG. 1. [Figure 5]Figure 4 is a cross-sectional view (AA) showing a solar cell string, with the terminal portion of the solar cell and the conductive adhesive exaggerated, and some hatching omitted. [Figure 6] Figure 4 is a perspective view showing the wiring components. [Figure 7] (a) is an image of an example in which a portion of a defective solar cell string was photographed in the first shooting operation of an inspection device similar to the inspection device in Figure 1, and (b) is an image of a comparative example in which the same portion of the same solar cell string as in (a) was photographed after being irradiated with light of a wavelength exceeding 420 nm. [Figure 8] This is a schematic diagram illustrating a defective solar cell string. [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described in detail below.

[0030] As shown in Figure 1, the inspection apparatus 1 of this embodiment includes a control device 2 and an imaging unit 3.

[0031] The control device 2 is a controller (a small computer) having a central processing unit composed of an arithmetic unit that performs calculations on data, and is capable of receiving signals from and outputting signals to external devices. Furthermore, the control device 2 has a storage means (not shown) capable of storing various types of data (information). The control device 2 may also have a separate main unit and storage means, connected in a manner that allows them to send and receive signals (information) to each other.

[0032] As shown in Figure 1, the control device 2 comprises a control unit 10, an image input unit 11, and a detection unit 12, and functions as the main body of the inspection device 1 (inspection device main body). The control unit 10 to the detection unit 12 are functional units, and functional units are functions realized, for example, by the processor reading a program stored in memory.

[0033] The control unit 10 is the part that controls the imaging unit 3.

[0034] The image input unit 11 is the part into which images captured by the imaging unit 3 are input. Specifically, the image input unit 11 receives the first judgment image data (details to be described later) acquired by the first imaging operation (details to be described later) and the second judgment image data (details to be described later) acquired by the second imaging operation (details to be described later).

[0035] The detection unit 12 is the part that detects defects in the object to be inspected (solar cell string 30, which will be described in more detail later) based on the images (first judgment image and second judgment image) input to the image input unit 11. In other words, the detection unit 12 is the part that determines whether or not there are defective parts in the photographed object to be inspected and identifies what kind of defects the defective parts are.

[0036] As shown in Figures 1 and 2, the imaging unit 3 comprises a first illumination unit 21, a second illumination unit 22, an imaging device 23, and an image base forming unit 24.

[0037] As shown in Figures 2 and 3, the first illumination unit 21 has two first illumination light source units 21a and 21b (first light source units). These two first illumination light source units 21a and 21b are positioned above the image base forming unit 24 by mounting means such as a stand (not shown). The two first illumination light sources 21a and 21b are arranged side by side with a gap between them in a predetermined direction (the second direction described later). Each of the first illumination light sources 21a and 21b is a light-emitting device that emits light with the same wavelength range (having peak wavelengths in the same wavelength range), and emits light with a wavelength of 360 nm to 420 nm. More preferably, the first illumination light sources 21a and 21b are light-emitting devices that emit light with a wavelength of 380 nm to 420 nm. In other words, it is more preferable that the first illumination light sources 21a and 21b emit visible light, specifically violet light.

[0038] As shown in Figure 3, the two first illumination light sources 21a and 21b extend linearly in a direction intersecting the direction of alignment (in this embodiment, a direction perpendicular to the alignment, and a third direction described later), and in this embodiment, they extend parallel to each other. The first illumination light sources 21a and 21b may be light-emitting devices formed by arranging point light sources such as LEDs in the direction of extension, or they may be light-emitting devices having a line light source extending in the direction of extension. That is, the first illumination light sources 21a and 21b have a linear light-emitting region extending in the direction of extension, or a planar light-emitting region having a longitudinal direction in the direction of extension. In the following explanation, the light emitted from the first illumination unit 21 (first illumination light source units 21a, 21b) will also be referred to as the first light.

[0039] As shown in Figures 2 and 3, the second illumination unit 22 has two second illumination light source units 22a and 22b (second light source units). These two second illumination light source units 22a and 22b are positioned above the image base forming unit 24 by mounting means such as a stand (not shown). The two second illumination light sources 22a and 22b are arranged side by side with a gap between them in a predetermined direction (the second direction described later). Each of the second illumination light sources 22a and 22b is a light-emitting device that emits light with the same wavelength range (having a peak wavelength in the same wavelength range), and more specifically, emits visible light with a wavelength of 600 nm or more. That is, the second illumination light sources 22a and 22b emit reddish-orange or red light. In this embodiment, the second illumination light sources 22a and 22b are light-emitting devices that emit red light with a wavelength of 640 nm or more.

[0040] These two second illumination light sources 22a and 22b also extend linearly in a direction intersecting the direction of alignment (in this embodiment, a direction perpendicular to the alignment, and a third direction described later), as shown in Figure 3, and in this embodiment, they extend parallel to each other. The second illumination light sources 22a and 22b may be light-emitting devices formed by arranging point light sources such as LEDs in the direction of extension, or they may be light-emitting devices having a linear light source extending in the direction of extension. That is, the second illumination light sources 22a and 22b have a linear light-emitting region extending in the direction of extension, or a planar light-emitting region having a longitudinal direction in the direction of extension. In the following explanation, the light emitted from the second illumination unit 22 (second illumination light source units 22a, 22b) will also be referred to as the second light.

[0041] As shown in Figures 2 and 3, the imaging device 23 is a camera with a monochrome shooting function and is an area camera that images an object as a whole. In other words, the imaging device 23 is a device that images an object and outputs a still image (image data). In this embodiment, the imaging device 23 is positioned above the image base forming unit 24 by mounting means such as a stand (not shown). From the above, the imaging unit 3 of this embodiment is capable of performing a first imaging operation in which it takes images while irradiating the target object (solar cell string 30 and the image base forming unit 24, which will be described later) with first light from the first illumination unit 21. In addition, the imaging unit 3 is capable of performing a second imaging operation in which it takes images while irradiating the target object with second light from the second illumination unit 22. Both the first imaging operation and the second imaging operation of this embodiment are monochrome imaging operations.

[0042] As shown in Figures 2 and 3, the image base forming section 24 is a flat plate-shaped member and is a first color section 24a that exhibits a predetermined color, either partially or entirely. More specifically, the image base forming section 24 has a surface on the imaging section 3 side (the top surface in this embodiment) and the portion including the mounting surface on which the object to be inspected is placed is the first color section 24a. Here, the first color is the same color as, or an approximate color of, the second light emitted by the second illumination unit 22. An "approximate color" here means a color with a hue difference of 3 or less. In this embodiment, the first color in the first color unit 24a is red. This image base forming unit 24 forms the background portion of the solar cell string 30, which is the object of inspection (subject), when the image data acquired in the first imaging operation and the second imaging operation is output in a visible state.

[0043] In this embodiment, the imaging unit 3 is capable of controlling the lighting and extinguishing of the first illumination unit 21 and the second illumination unit 22 individually. In other words, the two first illumination light sources 21a and 21b and the two second illumination light sources 22a and 22b can each be turned on and off individually. Hereinafter, in the following description, the longitudinal direction of the imaging axis P1 of the imaging device 23, which is the direction in which the imaging device 23 and the image base forming unit 24 face each other (the vertical direction in this embodiment), will also be referred to as the first direction. The first direction is also the direction in which the imaging device 23 and the object to be inspected face each other during imaging. Furthermore, one predetermined direction that is perpendicular to the first direction will also be referred to as the second direction, and the direction that is perpendicular to both the first and second directions will also be referred to as the third direction.

[0044] As shown in Figures 2 and 3, the imaging unit 3 is arranged such that, from one side in the second direction, one second illumination light source unit 22a, one first illumination light source unit 21a, the imaging device 23, the other first illumination light source unit 21b, and the other second illumination light source unit 22a are arranged in the same direction with spacing between them. That is, as shown in Figure 3, in a plan view, the imaging unit 3 is positioned with two first illumination light source units 21a and 21b between the two second illumination light source units 22a and 22b, and the imaging device 23 is positioned between the two first illumination light source units 21a and 21b.

[0045] Here, as shown in Figure 2, in a side view, distance L1 is defined as the distance in the second direction from the position where one of the two first illumination light sources 21a and 21b is located to the position where the other light source is located. Then, distance L2 is defined as the distance in the second direction from the position where one of the two second illumination light sources 22a and 22b is located to the position where the other light source is located. In this case, distance L2 is longer than distance L1.

[0046] Furthermore, the two second illumination light sources 22a and 22b are positioned such that one is located away from the imaging axis P1 in a second direction (towards one end of the imaging unit 3 in the second direction), and the other is located on the opposite end in the second direction. More specifically, as shown in Figure 2, the two second illumination light sources 22a and 22b are positioned symmetrically with respect to the imaging axis P1 in a second direction when viewed from the side, and are capable of irradiating the first light toward the same position.

[0047] At this time, as shown in Figure 2, the optical path of the illumination light (first light) from the first illumination light source unit 21a is at an angle inclined by a predetermined angle θ1 with respect to the imaging axis P1 of the imaging device 23 when viewed from the side. In other words, the first illumination light source unit 21a is capable of irradiating the object to be inspected (solar cell string 30) with the first light from a direction inclined by a predetermined angle θ1 with respect to the imaging axis P1. Similarly, the first illumination light source unit 21b is also capable of irradiating the object to be inspected with first light from a direction inclined by a predetermined angle θ1 with respect to the imaging axis P1. More specifically, the first illumination light source unit 21b is capable of irradiating first light from a direction inclined by a predetermined angle θ1 on the opposite side from the first illumination light source unit 21a. In this embodiment, the predetermined angle θ1 is between 0 degrees and 45 degrees, and more specifically, it is about 10 degrees. Note that the term "about" here includes an error of a few percent.

[0048] Similarly, the two second illumination light sources 22a and 22b are positioned such that one is located away from the imaging axis P1 in a second direction (towards one end of the imaging unit 3 in the second direction), and the other is located on the opposite side in the second direction (towards the other end of the imaging unit 3 in the second direction). In a side view, the two second illumination light sources 22a and 22b are positioned symmetrically with respect to the imaging axis P1 in a second direction, and are capable of irradiating the same position with second light. In other words, the two second illumination light sources 22a and 22b are also capable of irradiating the object to be inspected with light from a direction inclined by a predetermined angle θ2 with respect to the imaging axis P1, and more specifically, they are capable of irradiating the second light from directions inclined by a predetermined angle θ2 in opposite directions with respect to the imaging axis P1. Note that the predetermined angle θ2 in this embodiment is a larger angle than the predetermined angle θ1, and more specifically, it is about 30 degrees.

[0049] Here, let L3 be the distance in the first direction from the upper surface of the image base forming unit 24 (the mounting surface, the surface on the imaging device 23 side) to the position where the light sources of the second illumination light sources 22a and 22b are located. Let L4 be the distance in the first direction from the upper surface of the image base forming unit 24 to the position where the light sources of the first illumination light sources 21a and 21b are located. Furthermore, let L5 be the distance in the first direction from the upper surface of the image base forming unit 24 to the lower end of the imaging device 23 (the end on the image base forming unit 24 side). In this case, distance L4 is longer than distance L3, and distance L5 is longer than distance L4.

[0050] In other words, the light sources of the first illumination light sources 21a and 21b are positioned further from the image base forming unit 24 than the light sources of the second illumination light sources 22a and 22b (further from the object being inspected during imaging). Furthermore, the lens and light-receiving element of the imaging device 23 are positioned further from the image base forming unit 24 than the light sources of the first illumination light sources 21a and 21b.

[0051] In this embodiment, as shown in Figure 3, the imaging unit 3 is positioned such that, in a plan view, the imaging device 23 overlaps with the image base forming unit 24, and during imaging, it is positioned such that it overlaps with the image base forming unit 24 and the object to be inspected (solar cell string 30). In this embodiment, the image base forming unit 24 is plate-shaped with thickness in the first direction (front-to-back direction in Figure 3) and has a planar extension in a direction perpendicular to the first direction. The imaging device 23 is positioned so as to coincide with the center of the image base forming unit 24 in the second direction and the center in the third direction (the central portion in a plan view). Furthermore, during imaging, the imaging device 23 is positioned so as to coincide with the center of the object to be inspected in the second direction and the center in the third direction.

[0052] In this embodiment, the first illumination light sources 21a and 21b are arranged such that, in a plan view, a portion of them overlaps with the image base forming unit 24, and during shooting, a portion of them overlaps with the image base forming unit 24 and the object to be inspected (solar cell string 30). In detail, the first illumination light sources 21a and 21b are positioned so that their midpoints in the longitudinal direction (third direction) overlap with the image base forming unit 24. That is, in a plan view, one end of the first illumination light sources 21a and 21b in the longitudinal direction is positioned further outward than one end of the image base forming unit 24 in the same direction. Furthermore, in a plan view, the other end of the first illumination light sources 21a and 21b in the longitudinal direction is positioned further outward than the other end of the image base forming unit 24 in the same direction. Therefore, when viewed from a plan during imaging, both ends of the first illumination light sources 21a and 21b in the longitudinal direction are positioned further outward than both ends of the object to be inspected (solar cell string 30) in the same direction.

[0053] In contrast, the second illumination light sources 22a and 22b of this embodiment are positioned in a plan view such that they do not overlap with the image base forming unit 24 and the object to be inspected (solar cell string 30). Furthermore, the length of the second illumination light source units 22a and 22b in the longitudinal direction (third direction) is longer than the length of the image base forming unit 24 in the same direction. For this reason, the ends of the second illumination light source units 22a and 22b in the longitudinal direction are positioned further outward than the ends of the image base forming unit 24 in the same direction.

[0054] Next, we will describe the solar cell string 30, which is the object to be inspected by the inspection device 1 of this embodiment.

[0055] As shown in Figures 4 and 5, the solar cell string 30 is formed by attaching two wiring members 34 to a string body 30a, which is formed by electrically connecting multiple solar cells 32 in series. This solar cell string 30 is a component that forms part of a solar cell module (not shown). More specifically, a laminate is formed in which the solar cell string 30 and the sealing material are placed between a translucent substrate (not shown) that forms the light-receiving side of the solar cell module and a back sealing material (not shown) located on the opposite side. Then, a solar cell panel is formed by laminating this laminate. The solar cell module is formed by this solar cell panel itself, or by attaching other components such as a terminal box to this solar cell panel.

[0056] As shown in Figure 4, the solar cell 32 is a substantially rectangular panel member and has two long sides 32a and 32b that face each other in a predetermined direction (up and down in Figure 4) when viewed from above. As shown in Figure 5, the solar cell 32 has a negative electrode terminal portion 40 on one main surface and a positive electrode terminal portion 41 on the other main surface. The negative terminal portion 40 and the positive terminal portion 41 extend linearly along the longitudinal direction of the solar cell 32 (the length direction of the long sides 32a and 32b, which is the front-to-back direction in Figure 5). More specifically, one of the negative terminal portion 40 and the positive terminal portion 41 is located near one of the two long sides 32a and 32b, along that long side 32b. The other of the negative terminal portion 40 and the positive terminal portion 41 is located near the other of the two long sides 32a and 32b (for example, the upper long side 32a in Figure 5), along that long side 32a.

[0057] In this embodiment, the string body 30a is connected to adjacent solar cells 32 by overlapping portions, as shown in Figures 4 and 5. More specifically, as shown in Figure 5, the string body 30a is formed by the overlap of the portion around the short end of one solar cell 32, including the negative terminal portion 40, and the portion around the short end of the other solar cell 32, including the positive terminal portion 41. Furthermore, in this state, the negative terminal portion 40 and the positive terminal portion 41 overlap, and the negative terminal portion 40 and the positive terminal portion 41 are electrically connected. In other words, in this embodiment, the string body 30a is connected to multiple solar cells 32 by a so-called single-ring connection.

[0058] Furthermore, in this embodiment, the string body portion 30a has a negative terminal portion 40 and a positive terminal portion 41 connected via a conductive adhesive 45 (adhesive). The conductive adhesive 45 is a conductive material having conductivity, and is a conductive paste containing metal particles such as solder and flux.

[0059] As shown in Figures 4 and 6, the wiring member 34 is a thin, sheet-like wiring with a ladder-like shape when viewed from above, and includes a battery-side terminal portion 50, an output-side terminal portion 51, and an inter-terminal connection portion 52. The battery-side terminal portion 50 is the part that is connected to the negative terminal portion 40 or the positive terminal portion 41 via a conductive adhesive 45 (see Figure 5). The battery-side terminal portion 50 is an elongated, roughly rectangular portion with length in a predetermined direction (left-right direction in Figure 4).

[0060] The output terminal portion 51 is the part that connects to an external component when the solar cell module is formed, and its general shape is approximately the same as that of the battery-side terminal portion 50. That is, the output terminal portion 51 is an elongated, roughly rectangular portion that extends parallel to the battery-side terminal portion 50.

[0061] The terminal connection section 52 is composed of multiple small pieces arranged at intervals along the length of the battery-side terminal section 50 and the output-side terminal section 51, and is the part that connects the battery-side terminal section 50 and the output-side terminal section 51.

[0062] In this embodiment, as shown in Figure 4, one of the wiring members 34 of the solar cell string 30 is located at one end of the solar cell string 30 in the direction of arrangement of the solar cells 32 (up and down in Figure 4), and the other is located at the other end. When the solar cell string 30 is viewed from above, the battery-side terminal portion 50 of one of the wiring members 34 is located at the front of the solar cell string 30 and is exposed. The battery-side terminal portion 50 of the other wiring member 34 (not shown in Figure 4) is hidden at the back of the solar cell string 30. Of the two wiring members 34, one is connected to the positive terminal portion 41 located at the upstream end of the string body portion 30a in the direction of electrical flow. The other is connected to the negative terminal portion 40 located at the downstream end of the string body portion 30a in the direction of electrical flow.

[0063] Next, the inspection (visual inspection) of the solar cell string 30 performed by the inspection device 1 of this embodiment will be described in detail.

[0064] The inspection device 1 is capable of performing a first detection operation to detect a first defect and a second detection operation to detect a second defect. Before describing each detection operation, the defects to be detected will be described first. Note that either the first detection operation or the second detection operation may be performed, or both may be performed. Furthermore, if both the first and second detection operations are performed, they may be performed in this order or in the reverse order.

[0065] (First defect) The first defects include (1) through (4) below. Note that the first detection operation targets at least one first defect, and in this embodiment, all first defects are targeted for detection. (1) First flux stain (2) Second flux stain (3) Third flux stain (4)Human hair

[0066] "(1) First flux contamination" is an abnormality caused by the flux used during the manufacture of the solar cell string 30. In other words, the solar cell string 30 of this embodiment uses flux as an oxide decomposition agent to remove oxides from the surface of the solar cell 32 during manufacture. This first flux contamination is contamination caused by flux that occurs in the area outside the overlapping portion of the solar cell 32 and the wiring member 34. More specifically, the first flux contamination is contamination that has spread as if it had flowed out from the overlapping portion, as shown in the area enclosed by the line indicated by reference numeral A1 in Figure 7(a). In other words, in a plan view, the first flux contamination is contamination in which a part of the outer edge is adjacent to the overlapping portion.

[0067] "(2) Second flux contamination" is an abnormality caused by the flux used during the manufacture of the solar cell string 30, and this second flux contamination is also caused by flux that occurs in the area away from the overlapping portion of the solar cell 32 and the wiring member 34. In detail, the second flux contamination is contamination that spreads at a location away from the overlapping portion, as shown in the area enclosed by the line indicated by the symbol A2 in Figure 7(a). In other words, in a plan view, the second flux contamination is contamination where the entire edge surrounding the outer perimeter is located away from the overlapping portion.

[0068] "(3) Third flux contamination" is an abnormality caused by the flux used during the manufacture of the solar cell string 30, and is contamination caused by flux containing oil. Specifically, it is contamination caused by a worker touching the solar cell 32 with hands that have flux on them, and is flux contamination in the shape of at least a part of a human hand, such as a fingerprint or palm print, in whole or in part.

[0069] "(4) Human hair" refers to an abnormality caused by human hair such as scalp hair, and is a black linear appearance abnormality (not shown) resulting from the falling and contamination of workers' hair.

[0070] (Second defect) The second defects are (5) through (12) below. Note that the second detection operation targets at least one second defect, and in this embodiment, all second defects are targeted for detection. (5) (6) Chips (7) Surface scratches (8) Excess adhesive (9) Misalignment of solar cells (10) Orientation misalignment of solar cells (11) Terminal exposed (12) Wiring misalignment

[0071] "(5) Crack" is an anomaly in which a missing portion is formed on the edge of the glass of the solar cell 32, as shown in the enlarged portion indicated by the symbol B1 in Figure 8. The missing portion is a part that is missing from one end to the other in the thickness direction (a through-hole-shaped missing portion, which is the first missing portion).

[0072] "(6) Chip" is an anomaly in which a missing portion is formed on the edge of the glass of the solar cell 32, and the missing portion is a missing portion in which a part of the thickness direction from one end to the other is missing (a missing portion in the form of a bottomed hole, the second missing portion) (not shown).

[0073] "(7) Surface scratches" refers to an abnormality in which scratches are formed on the surface of the solar cell 32 in a part away from the edge.

[0074] "(8) Adhesive overflow" is an abnormality in which, as shown in the enlarged portion indicated by the symbol B2 in Figure 8, the conductive adhesive 45 adheres to a position other than the proper position in a plan view, and the conductive adhesive 45 is distributed in an area on the surface of the solar cell 32. In other words, it is an abnormality in which the conductive adhesive 45 overflows to the outside from between the negative electrode terminal portion 40 and the positive electrode terminal portion 41, or from between the wiring member 34 and the terminal portion (negative electrode terminal portion 40, positive electrode terminal portion 41).

[0075] "(9) Misalignment of solar cells" is an abnormality in which the solar cell 32 is positioned in a location different from its proper position, as shown in the third solar cell 32 from the top in Figure 8.

[0076] "(10) Misalignment of solar cell orientation" refers to an abnormality in which the solar cell 32 is positioned in an orientation different from the proper orientation, such as being rotated 180 degrees from its proper position, or being upside down.

[0077] "(11) Terminal Exposure" is an abnormality in which, as shown in the enlarged portions indicated by symbols B3 and B4 in Figure 8, at least a part of the terminal portion (positive terminal portion 41), which should not be exposed to the outside, is exposed in a plan view. This terminal exposure is an abnormality in which, in a plan view of the solar cell string 30, some member is not properly positioned in a position that overlaps with the terminal portion, and / or the terminal portion is positioned in a position different from where it should be. The enlarged portion indicated by symbol B4 in Figure 8 is an example in which terminal exposure occurred due to wiring misalignment, which will be described later.

[0078] "(12) Wiring misalignment" is an abnormality in which the wiring member 34 is not positioned in the correct location and / or is not positioned in the correct orientation, as shown in the upper wiring member 34 of Figure 8.

[0079] (First detection action) In the first detection operation for detecting the first defect, the inspection device 1 first places the solar cell string 30 to be inspected at a predetermined position on the image base forming unit 24, which is the shooting position. Although the solar cell string 30 is transported to the shooting position by a robot (not shown), it may also be transported manually by an operator. At this time, the solar cell string 30 is arranged to extend in a direction perpendicular to the imaging axis P1 of the imaging device 23 (see Figure 2) (horizontal direction), as shown in Figures 2 and 3. That is, the thickness direction of the entire solar cell string 30 is in the same direction as the extension direction of the imaging axis P1. Each of the solar cells 32 belonging to the solar cell string 30 is arranged so that the main surface (light-receiving surface in this embodiment) located on one side in the thickness direction of the solar cell string 30 faces the imaging device 23.

[0080] Next, the first illumination unit 21 emits first light, and a first shooting operation is performed to photograph the solar cell string 30 while it is illuminated by the first light. In this embodiment, the first shooting operation is performed with the second illumination unit 22 not emitting light. When this first shooting operation is performed, the first judgment image data acquired by the first imaging operation is input to the image input unit 11 (see Figure 1).

[0081] The inspection device 1 of this embodiment can acquire, by first shooting operation, image data in which the above-mentioned first defect is emphasized (detailed illustration omitted, see Figure 7(a), etc.) as first judgment image data. In other words, it is possible to acquire image data in which the first defect, which would not be visible or would be very difficult to see in the image when normal shooting is performed with illumination such as natural light, is made more prominent than the surrounding area (the surface portion of the solar cell 32).

[0082] Here, the first judgment image data (see Figure 7(a)) is compared with a comparison image (see Figure 7(b), an image acquired in the second shooting operation described later) taken under the same conditions except that the second light is irradiated on the same part of the same solar cell string 30. At this time, the first judgment image data is clearer and has a greater difference in density between the first defect and the surrounding area than the comparison image. In other words, the first shooting operation in this embodiment takes a picture of the solar cell string 30 when the first light is irradiated on it, thereby acquiring an image in which the difference in pixel values ​​of the density between the area where the first defect exists and the surface area of ​​the surrounding solar cells 32 is increased.

[0083] Next, the detection unit 12 analyzes the first judgment image data to determine whether or not there is a first defect and the type of first defect (which of (1) to (4) above). That is, if there is a first defect, the location and shape of the first defect are identified, and the type of the first defect is identified. In this way, the first defect of the solar cell string 30 is identified. The inspection device 1 of this embodiment performs detection and identification of the first defect based on first judgment image data that makes it easy to identify the location and shape of the first defect, so the detection and identification of the first defect can be performed with high accuracy.

[0084] (Second detection operation) In the second detection operation, the inspection device 1, in the same manner as in the first detection operation described above, positions the solar cell string 30 to be inspected at a predetermined position on the image base forming unit 24, which is the shooting position. Then, the second illumination unit 22 emits a second light, and a second imaging operation is performed to photograph the solar cell string 30 while it is illuminated by the second light. In this embodiment, the second imaging operation is performed with the first illumination unit 21 not emitting light. When this second imaging operation is performed, the second judgment image data acquired by the second imaging operation is input to the image input unit 11 (see Figure 1).

[0085] Next, the detection unit 12 analyzes the second judgment image data to determine whether a second defect exists and what type of second defect it is (which of (5) to (12) above). That is, if a second defect exists, the detection unit 12 identifies the location and shape of the second defect and the type of the second defect. This identifies the second defect in the solar cell string 30.

[0086] Furthermore, the second detection operation in this embodiment may also be an operation in which the second shooting operation is performed multiple times, and more specifically, from the viewpoint of more accurately distinguishing between cracks and chips, it may be an operation in which the second shooting operation is performed twice. In this case, the second shooting operation performed the first time and the second shooting operation performed the second time are operations in which light is irradiated in such a state that the brightness of the light-emitting area of ​​the second illumination unit 22 is higher than that of the other, and shooting is performed in each case. In the following explanation, an example is described in which the second shooting operation performed the first time is a high-brightness shooting operation, and the second shooting operation performed the second time is a low-brightness shooting operation.

[0087] The first second shooting operation (hereinafter also referred to as the high-brightness shooting operation) and the second second shooting operation (hereinafter also referred to as the low-brightness shooting operation) are performed under the same conditions as the second second shooting operation (hereinafter also referred to as the low-brightness shooting operation), except that different light (light with different brightness levels in the light-emitting area) is used to photograph the same part of the same solar cell string 30. At this time, the brightness of the light-emitting area of ​​the second illumination unit 22 in the high-brightness shooting operation is set to approximately twice the brightness of the light-emitting area of ​​the second illumination unit 22 in the low-brightness shooting operation. In addition, the illuminance of the second illumination unit 22 in the high-brightness shooting operation is set to approximately 1.67 times the illuminance of the second illumination unit 22 in the low-brightness shooting operation. Note that "approximately" here includes an error of a few percent.

[0088] When a high-brightness shooting operation or a low-brightness shooting operation is performed, the second judgment image data acquired by the high-brightness shooting operation (hereinafter also referred to as high-brightness image data) and the second judgment image data acquired by the low-brightness shooting operation (hereinafter also referred to as low-brightness image data) are input to the image input unit 11.

[0089] Here, when high-luminance image data is output in a visible state, the image will show both the chip and the crack (detailed illustration omitted). On the other hand, when low-luminance image data is output in a visible state, the image will show the chip but the crack will not be shown or will be barely shown (detailed illustration omitted).

[0090] Therefore, by analyzing the high-luminance image data and the low-luminance image data, the detection unit 12 can detect and identify chips and cracks with higher accuracy than when detecting and identifying them based solely on the high-luminance image data. For example, the detection unit 12 identifies the presence and location of a chip by identifying the parts of the low-luminance image data that are illuminated (appearing as high-luminance white). Simultaneously or before / after, the detection unit 12 creates differential image data by subtracting the low-luminance image data from the high-luminance image data, and identifies the presence and location of cracks by analyzing the differential image data. In this case, the detection and identification of other second defects (items (7) to (12) above) may be performed by analyzing either high-luminance image data or low-luminance image data, but it is preferable to perform the detection and identification by analyzing high-luminance image data for high accuracy.

[0091] In this embodiment, it is preferable that the inspection device 1 performs both the first detection operation and the second detection operation. With this configuration, the inspection device 1 can appropriately detect and identify the various types of defects described above (defects (1) to (12) above).

[0092] In the embodiments described above, the components can be freely substituted or added between each embodiment, as long as they fall within the technical scope of the present invention. [Explanation of symbols]

[0093] 1. Inspection device 3. Imaging Unit 12 Detection unit 21. First Lighting Section 21a First illumination light source section (first light source section) 21b First illumination light source section (first light source section) 22. Second Lighting Section 24 Image base forming unit 30 solar strings 32 solar cells 34 Wiring components 45. Conductive adhesive (adhesive)

Claims

1. An inspection device for detecting defects in a solar cell string, which is part of a solar cell module, in which solar cells and wiring components are connected using adhesive, It has an imaging unit and a first illumination unit, The first illumination unit is capable of irradiating the solar cell string with first light having a wavelength of 360 nm or more and 420 nm or less. The imaging unit is capable of performing a first imaging operation to photograph the solar cell string while it is illuminated with the first light. An inspection device having a detection unit that detects a first defect based on image data created by the first shooting operation.

2. The inspection apparatus according to claim 1, wherein the first defect is a defect caused by an oxide decomposing agent containing oil.

3. The inspection apparatus according to claim 1 or 2, wherein the adhesive contains components similar to those of an oxide decomposing agent that may cause the first defect.

4. The inspection apparatus according to claim 1 or 2, wherein the first illumination unit irradiates the solar cell string with light from a direction inclined at an angle of 0 degrees or more and 45 degrees or less with respect to the imaging axis of the imaging unit.

5. The first illumination unit has a first light source unit that emits light, The aforementioned solar cell string is arranged to extend in a direction perpendicular to the imaging axis of the imaging unit, The inspection apparatus according to claim 1 or 2, wherein the first light source extends linearly in the direction of the spread of the solar cell string.

6. It has a second lighting section, The second illumination unit is capable of irradiating the solar cell string with a second light that is visible light and has a wavelength of 600 nm or more. The imaging unit performs a second imaging operation to photograph the solar cell string when it is illuminated with the second light. The inspection apparatus according to claim 1, wherein the detection unit detects a second defect different from the first defect based on image data created by the second shooting operation.

7. The inspection apparatus according to claim 6, wherein both the first shooting operation and the second shooting operation create a grayscale image, and the first defect, when represented by the image data created by the first shooting operation, has a greater contrast in density with adjacent parts than when represented by the image data created by the second shooting operation.

8. The inspection apparatus according to claim 6 or 7, wherein the second defect includes a first missing portion which is a missing portion that penetrates any part of the solar cell string, and a second missing portion which is a missing portion that does not penetrate any part of the solar cell string, and the apparatus identifies and detects whether the defect is the first missing portion or the second missing portion.

9. Having an image base forming unit, The second imaging operation is performed by arranging the solar cell string between the imaging unit and the image base forming unit. The inspection apparatus according to claim 6 or 7, wherein at least a portion of the surface of the solar cell string side of the image base forming unit exhibits substantially the same color as the second light.

Images