WO2010064720A1 - Apparatus and method for inspecting solar cell, and recording medium having program of the method recorded thereon - Google Patents

Abstract

Provided is an apparatus for inspecting a solar cell having a high cell use efficiency, said apparatus being configured so as to determine whether the quality of the solar cell is acceptable or not by analyzing in detail a solar cell image obtained by photographing the solar cell. The apparatus for inspecting the solar cell includes: an image acquiring unit (5) which acquires the cell image which depicts the solar cell in the state wherein a current is carried therein; a defect determining unit (2A) which identifies defects in the solar cell based on the solar cell image; and a defect region identifying unit (2B) which identifies regions where defects exist and regions where defects do not exist in the solar cell, based on the results of the identification of the solar cell defects.

Description

Solar cell inspection device, inspection method, and recording medium recording the program

The present invention relates to a solar cell inspection device for inspecting a solar cell having a function of generating electricity by light, a solar cell inspection method, and a recording medium recording the program.

A method and apparatus for inspecting a defect in a solar battery cell by energizing the solar battery cell to emit EL light is described in Patent Document 1 below.
FIG. 15 is a diagram schematically showing the configuration of the inspection apparatus described in Patent Document 1. As shown in FIG. Referring to FIG. 15, the inspection apparatus 100 includes a dark room 110, a CCD camera 120 provided on the dark room 110, and a power supply 140 that supplies current to the solar cells 130 placed on the floor of the dark room 110. The image processing apparatus 150 is configured to process an image signal from the CCD camera 120.
The dark room 110 has a window 110a. A finder 120a of the CCD camera 120 is provided here, and a photographed image of the CCD camera 120 can be confirmed by looking into it with the naked eye. A personal computer is used as the image processing apparatus 150. By inspecting the solar battery cell with such an inspection device, a defect in the solar battery cell can be detected. Because it only determines the quality of the solar cell according to the degree of the defect, it is only possible to determine whether it can withstand use at the present time, and it is not possible to know in detail what the solar cell is. It was not considered whether or not there was a possibility of failure when used for a long time. Also, if it is determined that it cannot be used, it is discarded as it is or dissolved and recycled.
However, according to the solar cell inspection apparatus of the prior art, since the defect of the solar cell cannot be determined in detail, the class of the solar cell and the performance of the solar cell module cannot be accurately determined.
In addition, according to the prior art, since only the class of the entire solar battery cell can be determined, there is a problem that it is determined that what can be partially used cannot be used as a whole. Moreover, solar cells are extremely expensive and difficult to procure, and this problem has become prominent. Moreover, since the performance of the solar cell is deteriorated in the solar cell having defects, the solar cell inspection apparatus of the prior art cannot be partially reused as a high-performance solar cell effectively. .
Furthermore, according to the conventional technique, the type of defect and the degree of defect (defect length, area, etc.) cannot be determined accurately. Therefore, it is possible to incorporate a solar cell with a defect that cannot be determined whether it is a defect that progresses poorly over a long period of use into a solar cell module. Even if it progresses to the chip, it cannot be confirmed what the state of the defect of the cell was before it was incorporated into the solar cell module. In addition, the accuracy of the defect determination of the conventional solar cell inspection device does not change as it was originally made (the accuracy does not improve), and depends on the degree of defects before use. There is no description about the correlation of missing information in use. In other words, there is no description of improving the quality of a solar battery cell or a solar battery module incorporating it by feedback processing of the defect state of the solar battery cell in use to a solar cell inspection apparatus.
WO / 2006/059615

The present invention has been made in view of such a situation, and its purpose is to make it possible to accurately determine the quality of a solar cell by analyzing in detail the image of the solar cell obtained by photographing, An object of the present invention is to provide a solar cell inspection apparatus with high cell use efficiency, a solar cell inspection method, and a recording medium recording the program. A further purpose is to use a detailed analysis of solar cell images to understand the correlation of what defects (dark areas) are missing during use, and to obtain the results of the solar cell defects. An object of the present invention is to provide a solar cell inspection apparatus, a solar cell inspection method, and a recording medium recording the program, which can be fed back to the determination method to further improve the accuracy of defect determination.

An inspection apparatus for a solar cell according to one embodiment of the present invention includes an image acquisition unit that acquires a cell image representing a solar cell in an energized state, and a defect determination that determines a defect of the solar cell using the solar cell image. A marking device provided outside the solar cell inspection device for marking at least the solar cell identification symbol information on the solar cell. It is characterized by. According to this one aspect, since the identification symbol is given to the solar battery cell, when a defect occurs during use, the content can be fed back to further improve the accuracy of the defect determination.
Moreover, in the inspection apparatus of the photovoltaic cell of such an aspect, it is good also as a structure which provided the marking part inside the inspection apparatus of a photovoltaic cell. Furthermore, it can also be set as the structure which provides a marking apparatus outside the test | inspection apparatus simultaneously with providing a marking part inside the test | inspection apparatus of a photovoltaic cell.
The solar cell inspection device of one embodiment of the present invention is made of at least cracks and cracks by an image acquisition unit that acquires a cell image representing a solar cell in an energized state and a captured image of the solar cell. It is determined that there is a possibility that the dark area information brighter than the defect may become a defect, and the image obtained by binarizing the photographed image is compared with the dark area information brighter than the defect formed by the crack. And a defect determination unit that accurately determines a defect. According to this aspect, since it is possible to accurately determine whether or not each defect is a defect, the class determination of the solar battery cell becomes accurate. According to this aspect, it is possible to accurately determine whether or not each defect that can be regarded as a defect is a defect.
Moreover, in the inspection apparatus of the solar cell of such an aspect, it is good also as a structure which provided the marking apparatus outside the inspection apparatus of the solar battery cell, or as a structure which provides a marking part inside the inspection apparatus of a solar cell. good. Furthermore, it can also be set as the structure which provides a marking apparatus outside the test | inspection apparatus simultaneously with providing a marking part inside the test | inspection apparatus of a photovoltaic cell.
An inspection apparatus for a solar cell according to one embodiment of the present invention includes an image acquisition unit that acquires a cell image representing a solar cell in an energized state, and a defect determination that determines a defect of the solar cell using the solar cell image. And a region where the solar cell is defective and a region where there is no defect based on the defect determination result of the solar cell, and at least a boundary between the region where the solar cell is defective and the region where there is no defect And a defect area determination unit that generates defect area determination information including boundary line information that can be identified. According to this aspect, it is possible to accurately identify a portion that can be determined as a non-defective product in a solar cell that is determined to be defective. Eventually, the use efficiency of the solar battery cell is increased.
Moreover, in the inspection apparatus of the solar cell of such an aspect, it is good also as a structure which provided the marking apparatus outside the inspection apparatus of the solar battery cell, or as a structure which provides a marking part inside the inspection apparatus of a solar cell. good. Furthermore, it can also be set as the structure which provides a marking apparatus outside the test | inspection apparatus simultaneously with providing a marking part inside the test | inspection apparatus of a photovoltaic cell.
The method for inspecting a solar battery cell according to one embodiment of the present invention is brighter than at least cracks and cracks caused by cracks, by the step of obtaining a cell image representing an energized solar battery cell and the image of the solar battery cell. It is brighter than the image obtained by binarizing the photographed image, the crack, and the chip formed by the crack. A step of determining a dark region by deleting a dark region due to noise in comparison with the dark region information, and a step of determining the quality of the solar battery cell based on the determined defect and a cell image obtained from the dark region; It is characterized by including. According to this aspect, since it is possible to accurately determine whether or not each defect that can be regarded as a defect is a defect, the accuracy of the solar cell class determination is improved.
The recording medium on which the photovoltaic cell inspection program of one embodiment of the present invention is recorded includes a process of obtaining a cell image representing a solar cell in an energized state, a process of determining a defect from the solar cell image, A process of determining a dark area from the captured image and causing a computer to execute a process of scanning a cell image including a dark part due to the defect in a direction perpendicular to the bus bar of the solar battery cell and determining an area without a defect. It is a feature. According to this one aspect, in the solar battery cell, a usable part can be accurately determined.

According to the present invention, in the determination of the class of solar cells, the accuracy of determination of a defect that may develop into a large defect in the future during use and the use efficiency of the solar cell can be increased.

FIG. 1 is an explanatory diagram of a solar battery cell.
FIG. 2 is a block diagram illustrating a configuration example of the solar cell inspection apparatus according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram illustrating a configuration example of a control unit of the solar cell inspection apparatus according to Embodiment 1 of the present invention.
FIG. 4 is a flowchart showing a solar cell inspection method according to Embodiment 1 of the present invention.
FIG. 5 is a diagram illustrating an example of a solar battery cell image.
FIG. 6 is an explanatory diagram of generation of crack position information.
FIG. 7 is an explanatory diagram of generation of dark region position information.
FIG. 8: is a block diagram showing the structural example of the control part of the inspection apparatus of the photovoltaic cell which concerns on Example 2 of this invention.
FIG. 9 is a flowchart showing a method for inspecting a solar battery cell according to Example 2 of the present invention.
FIG. 10 is a flowchart for explaining in detail the defect area determination method.
FIG. 11 is an explanatory diagram 1 of the defect area determination means.
FIG. 12 is an explanatory diagram 2 of the defect area determination means.
FIG. 13 is a drawing showing a light receiving surface (a) and a back surface (b) of a marked solar battery cell.
FIG. 14 is a drawing showing a modification of the first embodiment and the second embodiment.
FIG. 15 is a diagram showing a conventional solar cell inspection apparatus.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Solar cell inspection apparatus 3 Current supply part 4 Positioning part 5 Imaging part 7 Marking part 8 Operation part 9 Display part 10 Semiconductor substrate 11 Finger part 12 Bus bar part 13 Back surface side electrode 14 Connection part 2A Defect determination part 2B Defect region determination unit 20 Control unit 21 Energization control unit 22 Position control unit 23 Image acquisition unit 24 Crack position information generation unit 25 Crack determination unit 26 Dark region position information generation unit 27 Dark region determination unit 28 Quality determination unit 29 Display control unit 30 Cell image 32a, 32b, 32c Crack 34a, 34b, 36 Dark region 37 Grain boundary 42a, 42b, 42c, 46, 47 Boundary part of change in brightness 57 Dark region 61a, 61b corresponding to grain boundary 37 Defective Marking to indicate the area Identification symbol 62a, 62b Identification symbol 63a, 63b Identification cell 63a, 63b Identification symbol 64, 65 Boundary line 70 Solar cell identification symbol 71 Classification information 72 Identification symbol 72 Threshold information identification 80 Marking device DESCRIPTION OF SYMBOLS 100 Solar cell inspection apparatus 110 Dark room 120 CCD camera 130 Solar cell 140 Power supply 150 Image processing apparatus

First, before describing an embodiment of the present invention, a difference between a defect of a solar battery cell and a cell image obtained by imaging the solar battery cell will be described. As a portion where the brightness of the obtained cell image is low, there are a crack (1) and a dark region. Among the dark areas, there are obviously dark areas and slightly dark areas (areas that are clearly brighter than the dark areas). Among the darker dark areas, there are a dark area (2) caused by a crystal grain boundary and a dark area (3) produced at least partially surrounded by cracks. There are apparently dark areas (4) that do not emit light at all as defects due to current cracks and dark areas (5) that do not emit light as defects due to finger disconnection.
Among these, (2) is neither a defect nor a chip. (4) (5) is a defect, which leads to a decrease in the efficiency of the solar cell. (1) (3) is a defect, but it cannot be said that it is missing in the present state. It is a part that can be determined to be. According to the present invention, it is possible to classify the above types of defects in detail to increase the use efficiency of the solar battery cell.

Example 1 is a means for enabling a result of actual use of a solar cell module incorporated in a solar cell module to be fed back to the defect determination of the solar cell inspection device, and more accurately determining the defect of the solar cell inspection device; Is the method.
FIG. 1 is a view showing a solar battery cell according to the present embodiment, in which FIG. 1 (a) is a plan view on the light receiving surface side of the solar battery cell, and FIG. 1 (b) is a view of the solar battery cell. It is a top view on the back side. The solar battery cell 1 includes a semiconductor substrate 10 and electrodes provided on the light receiving surface and the back surface of the semiconductor substrate 10.
The semiconductor substrate 10 is formed in a flat plate shape having, for example, a rectangular shape with a side of approximately 150 mm square and a thickness of approximately 0.16 mm. The semiconductor substrate 10 is formed using an elemental semiconductor such as single crystal silicon, polycrystalline silicon, and amorphous silicon, a compound semiconductor, or the like. The semiconductor substrate 10 has a function of converting light energy into electrical energy.
Finger portions 11 and bus bar portions 12 are provided on the light receiving surface of the semiconductor substrate 10 (see FIG. 1A). A plurality of finger portions 11 are provided in parallel from one side of the semiconductor substrate 10 to the opposite side. The fingers 11 collect the electrons generated on the light receiving surface side of the semiconductor substrate 10. The bus bar portion 12 is a light receiving surface side electrode, and two bus bar portions 12 are provided in parallel across one side facing from one side of the semiconductor substrate 10 in a direction orthogonal to the direction in which the finger portions 11 are provided. The bus bar portion 12 collects electrons collected by the finger portion 11 and is connected to a tab lead.
On the back surface opposite to the irradiation surface of the semiconductor substrate 10, a back surface side electrode 13 and a connection portion 14 are provided (see FIG. 1B). The back side electrode 13 is provided over the entire back side of the semiconductor substrate 10. The back surface side electrode 13 is formed by, for example, baking aluminum after applying aluminum on the back surface of the semiconductor substrate 10. The back surface side electrode 13 collects holes generated on the back surface side of the semiconductor substrate 10. A plurality of connection portions 14 are intermittently provided on the back surface of the semiconductor substrate 10, for example, eight locations in the drawing. More specifically, the connecting portion 14 is a position symmetrical to the bus bar portion 12 provided on the light receiving surface of the semiconductor substrate 10 and a virtual central plane crossing the center of the thickness of the semiconductor substrate 10. 14 is formed to have a gap of a predetermined distance at regular intervals. The connection portion 14 may be formed by vapor-depositing solder on the back surface side electrode 13. A tab lead is connected to the connecting portion 14.
In the present invention, the solar battery cell may be a thin film solar battery cell.
FIG. 2 is a block diagram illustrating a configuration example of the solar cell inspection apparatus according to the present embodiment. In this solar cell inspection apparatus 2, an energization section 3, a positioning section 4, an imaging section 5, a marking section 7, an operation section 8, and a display section 9 are connected to a control section 20 that controls the entire apparatus. In this inspection apparatus, the number of solar cells to be measured may be one or plural. Further, when a plurality of solar cells are arranged in the solar cell inspection apparatus of this embodiment, a plurality of solar cells may be separately arranged in the inspection apparatus, or solar cells are arranged by tab leads. A string connected in a straight line may be used, or a panel-like structure in which a plurality of strings are connected in parallel may be arranged.
The energization unit 3 energizes the solar battery cell as the inspection target in response to a command from the control unit 20. The energization unit 3 supplies a forward current to each of the one or more solar cells using a probe (not shown). In FIG. 2, the case where only one photovoltaic cell is installed is illustrated.
The imaging unit 5 is configured with a CCD camera or the like, and images one or more solar cells in an energized state in response to a command from the control unit 20. The marking unit 7 includes a solar cell identification symbol, a class symbol, and a defect-free region and a defect-free region in an embodiment described later based on the result of the defect determination of the solar cell inspected based on the result of imaging of the solar cell. Mark the boundary line. The positioning unit 4 moves and positions the imaging unit 5 to a predetermined imaging position of each solar battery cell in accordance with a command from the control unit 20. Further, when a plurality of solar cells to be inspected are arranged in the apparatus, the energization unit 3 and the marking unit 7 are also moved to predetermined positions by the positioning unit 4 and positioned.
The interaction of these parts will be described. The imaging unit 5 is moved by the positioning unit 4 and sequentially images one or more solar cells arranged in the solar cell inspection apparatus. Moreover, the data of the cell image showing a photovoltaic cell obtained by this is input into the control part 20 sequentially. Based on the input image data, the defect determination unit (see 2A in FIG. 3) in the control device determines whether or not there is a defect. And an identification symbol etc. are provided by the marking part 7 provided in the inspection apparatus.
Such solar cell imaging is performed in a dark room. Further, since the EL (electroluminescence) light of the solar battery cell is weak, a camera with relatively high sensitivity is suitable as the imaging unit 5.
The control unit 20 is configured as a computer including a CPU (Central Processing Unit) and a RAM as a work area thereof. The control unit 20 may include a storage unit that stores programs and data necessary for the operation of the CPU. The operation unit 8 includes a keyboard, a mouse, and the like, and transfers operation inputs based on user operations to the control unit 20. The display unit 9 is composed of a liquid crystal display or the like, and displays an image corresponding to a display command from the control unit 20.
FIG. 3 is a block diagram illustrating a functional configuration example of the control unit, and FIG. 4 is a flowchart illustrating a solar cell inspection method realized in the control unit. The control unit 20 functionally includes an energization control unit 21, a position control unit 22, an image acquisition unit 23, a defect determination unit 2A, a quality determination unit 28, and a display control unit 29. And each part performs the said process, when CPU runs the program stored in the memory | storage part.
The energization control unit 21 controls the energization unit 3 to energize one or more solar cells 1. Thereby, each photovoltaic cell 1 emits EL light. Here, data of energization conditions such as a voltage value, a current value, and an energization time are stored in the storage unit of the control unit 20.
The position control unit 22 controls the positioning unit 4 to execute position control of the imaging unit 5, the energization unit 3, and the marking unit 7. Specifically, the position control unit 22 sequentially moves the imaging unit 5 to each imaging position where each solar cell 1 can be imaged, sequentially moves the energization unit 3 to the position of each solar cell 1, and further performs marking. The part 7 is sequentially moved to the position of each solar battery cell. Such imaging positions are determined by the size and number of solar cells 1, the arrangement interval, and the like, and are stored as data in the storage unit of the control unit 20.
The image acquisition unit 23 acquires cell image data representing the energized solar cell from the imaging unit 5 (S1). In addition, the image acquisition unit 23 performs preprocessing of the acquired cell image (S2). As the cell image preprocessing, for example, scaling processing for standardizing the brightness of the EL light of the solar battery cell 1, cell area extraction processing for extracting the solar battery cell 1 area, and the bus bar 12 portion of the solar battery cell 1 are excluded. There are a bus bar exclusion process, a shading process for correcting a brightness difference caused by the lens of the imaging unit 5, and the like.
Then, the image acquisition unit 23 outputs the cell image data subjected to the preprocessing to the defect determination unit 2A. The defect determination unit 2A includes a crack position information generation unit 24, a crack determination unit 25, a dark region position information generation unit 26, and a dark region determination unit 27.
FIG. 5 is a diagram illustrating an example of the cell image 30. In the cell image 30, the defective part of the solar battery cell 1 appears as a dark part with relatively low brightness. Such defective portions include cracks 32a, 32b, 32c and dark regions 34a, 34b. Here, one cell image includes at least hundreds of thousands to millions of images, and even a defect that cannot be confirmed with the naked eye can be determined as an image group of the cell image.
The cracks 32 a, 32 b, and 32 c appear as a linear pixel group with low brightness in the cell image 30. These cracks 32a, 32b, and 32c have a large difference in brightness from portions that emit light well. Such cracks 32a, 32b, and 32c are considered to be caused by heat when soldering the tab lead to the bus bar 12 or the connecting portion 14, or a load or impact during processing or transportation.
As another dark region, there is a dark region caused by cell chipping or finger disconnection.
The dark regions 34a and 34b appear in the cell image 30 as a pixel group having a certain area or more and low brightness. Such dark regions 34a and 34b are generated when current supply is inhibited by the cracks 32a and 32b. That is, the dark areas 34a and 34b are caused by the cracks 32a and 32b. Accordingly, the cracks 32a and 32b often overlap at least a part of the outer edges of the dark regions 34a and 34b. In addition, the brightness of the dark areas 34a and 34b is not uniform, and there are a dark area 34a having a slightly lower brightness than the surrounding area and a dark area 34b having a clearly lower brightness. It should be noted that in the dark region 34b where the lightness is clearly low, even if a crack 32b occurs at the outer edge, the lightness is almost the same, and therefore it may be difficult to distinguish between the two.
Further, the dark region 36 is also generated by finger disconnection. In this case, a dark region is formed in a rectangular shape between fingers arranged at right angles to the bus bar of the solar battery cell.
In addition, the crystal grain boundary 37 of the solar battery cell 1 may appear in the cell image 30. Such a crystal grain boundary 37 is not a defect of the solar battery cell 1 but appears in the cell image 30 as a pixel group having a slightly lower brightness than the surroundings. Such crystal grain boundaries 37 often have a relatively small shape.
Returning to FIG. 3 and FIG. The crack position information generation unit 24 of the defect determination unit 2A identifies the cracks 32a, 32b, and 32c in the cell image 30, and generates information on the positions and shapes of the cracks 32a, 32b, and 32c (S3). The information on the crack position / shape generated in this way is output to the quality determination unit 28 and the display control unit 29 through the crack determination unit 25 and the dark region determination unit 27. Specifically, the crack determination unit 25 identifies the positions of the cracks 32 a, 32 b, and 32 c by extracting the boundary part of the brightness change in the cell image 30. Such extraction of the boundary portion can be realized by using a differential filter or the like. The information on the crack position / shape includes information that is not actually a crack, and the crack is determined by excluding it (S4). An example of determining a crack is performed as follows.
FIG. 6 is an explanatory diagram of generation of crack position / shape information. When the differential filter is applied to the cell image 30 shown in FIG. 5, boundary portions 42a, 42b, 42c, 46, and 47 of brightness changes are extracted as shown in FIG. Among these, the boundary portions 42a, 42b, and 42c correspond to the cracks 32a, 32b, and 32c, respectively, and the boundary portion 47 corresponds to the crystal grain boundary 37. The boundary portion 46 corresponds to the finger break portion 36. Therefore, the boundary portion becomes thicker as the difference in brightness increases in the cell image.
The crack position information generation unit 24 sorts the boundary portions 42a, 42b, and 42c extending in the same thickness from the boundary portions 42a, 42b, 42c, 47, and 46 extracted in this way, The positions of the cracks 32a, 32b, and 32c can be specified.
Here, extending as a line means that a circular part such as a crystal grain boundary that is not a defect is excluded by removing a linear part (closed curve) where the start point and the end point cannot be distinguished (crystals) Grain boundary distinction processing 1) and quadrilaterals caused by finger breakage can be excluded (disconnection distinction processing 1).
In a further method, the crack position information generation unit 24 can determine a region appearing as a rectangle in the cell image as a boundary portion due to finger breakage in order to distinguish a defect due to finger breakage from a crack. If the outer edge of the quadrangle is vertical and horizontal in the entire cell image, it can be determined that it is due to a finger break (disconnection distinguishing process 2).
Further, the following prevention means may be additionally or selectively employed so that harmless things such as crystal grain boundaries are not determined as defects. The aspect ratio (ratio between the length in the longitudinal direction and the length in the width direction) of the minimum rectangle surrounding the pixel group constituting the boundary portions 42a, 42b, 42c, and 47 is also obtained. Here, the angle of one side of the two-dimensional minimum rectangle is not necessarily limited to 0 degrees and 90 degrees in comparison with the cell image, and may be extended toward a certain angle. A threshold for this aspect ratio is set, and it is determined that a threshold smaller than the set value is not a defect. Since the crystal grain boundary has a relatively small substantially circular shape, the aspect ratio is a small numerical value, so that the crystal grain boundary can be prevented from being determined as a crack (crystal grain boundary distinction process 2).
Furthermore, in this grain boundary distinction process 2, in order to distinguish from the boundary part by finger disconnection, the brightness in a boundary part can also be utilized. In this manner, the disconnection distinguishing process 2 is not performed, and even if only the crystal grain boundary distinguishing process 2 is performed, it can be distinguished from the boundary portion due to the finger disconnection. However, the accuracy is further increased by performing each processing simultaneously.
Note that the crack determination unit 25 compares the length of each crack with the threshold value to be determined as a crack based on the image information from the crack position information generation unit 24, and excludes those below the threshold value from the crack. Then, the image noise generated at the time of imaging is considerably excluded.
Returning to FIG. 3 and FIG. The dark region position information generation unit 26 performs binarization processing on the cell image 30 and specifies a dark pixel group having a predetermined area or more, thereby indicating dark region position information representing the positions of the dark regions 34a, 34b, and the like. Is generated (S5). The dark area position information generated in this way is output to the dark area determination unit 27.
Here, the threshold value of the brightness of the binarization process is set to such an extent that each pixel in the dark region 34a (see FIG. 5) whose brightness is slightly lower than the surroundings is determined as a dark pixel.
FIG. 7 is an explanatory diagram of generation of dark region position information. When the binarization process using such a threshold is performed on the cell image 30 shown in FIG. 5, as shown in FIG. 7, in addition to the dark regions 34a and 34b caused by the cracks 32a, 32b, and 32c, crystals Both the dark region 57 corresponding to the grain boundary 37 and the dark region 36 corresponding to the disconnection may be extracted.
In addition, the brightness of the outer peripheral portion of the solar battery cell 1 is slightly lower than the brightness of the central part, and the brightness of the light emitted from the individual solar battery cells 1 varies. However, an unintended dark region may be extracted in the binarization process. Therefore, the dark region position information includes unintended dark regions such as the dark region 57 corresponding to the crystal grain boundary 37 in addition to the information indicating the positions of the dark regions 34a and 34b caused by the cracks 32a, 32b, and 32c. May be included. The dark area position information includes coordinate information of the dark areas 34a and 34b. The dark area position information also includes coordinate information of the outer edges of the dark areas 34a, 34b and the like. Specifically, the outer edge of each dark region 34a, 34b, etc. is defined as a combination of straight lines, and the coordinate information of the start point and end point of each straight line is included in the dark region position information. The dark region position information may include information on the areas of the dark regions 34a and 34b.
Returning to FIG. 3 and FIG. The dark area determination unit 27 is caused by the cracks 32a, 32b, and 32c among the dark areas 34a, 34b, 36, and 57 extracted in S4 based on the input crack position information and dark area position information. The dark areas 34a and 34b are determined (S6). The boundary between the dark region of the finger break and the dark region due to the grain boundary is not determined to be a crack. Therefore, for example, the dark region where the dark region position information including the coordinate information of the start point and the end point of the outer edge of the dark region is not compared with the crack position / shape information output from the crack position information generating unit 24 is not overlapped. Excludes the world. The dark region determination unit 27 corrects the dark region position information according to the determination result, and outputs the result to the quality determination unit 28 and the display control unit 29.
The quality determination unit 28 determines the number or / and length of the cracks 32a, 32b, and 32c specified in the cell image 30, the number or / and size of the dark areas 34a and 34b caused by the cracks 32a and 32b, and fingers Based on the number or / and size of the dark regions 36 due to disconnection, the quality of the solar cells 1 shown in the cell image 30 is determined, and classification is performed (S7). Information on the quality class is output to the display control unit 29. Here, for the quality determination, a simple sum of the numbers of cracks 32a, 32b, 32c and dark regions 34a, 34b may be used, or a weighted sum corresponding to these types may be used. A weighted sum corresponding to the size (area) or length may be used.
The class information of the solar battery cell determined by the quality determination unit 28 is output (transferred) to the marking unit 7. Here, since a dark area information brighter than a simple crack or a chip formed by the crack may be a defect, it is taken into consideration for the determination of the class.
The display control unit 29 displays a display image for identifying and displaying the cracks 32a, 32b, and 32c identified in the cell image 30, the dark regions 34a and 34b caused by the cracks 32a and 32b, and the dark region 36 due to finger breakage. Display control is performed (S8), and the display image is displayed on the display unit 9 (S9). The display control unit 29 may identify and display the quality class of the solar battery cell 1 based on information from the quality determination unit 28. Based on the result of the quality determination unit 28, the marking unit 7 transfers information such as the class of solar cells and the identification symbol of the solar cells to the marking unit 7 (S12). Then, the transferred information is marked on the solar battery cell (S10). The marking operation of the class and the identification symbol of these solar cells can be realized by using a known laser irradiation device. Moreover, the marking part which consists of this laser irradiation apparatus can also be provided in the inspection apparatus of the photovoltaic cell of this invention, and can also be installed separately as the marking apparatus outside the inspection apparatus of a photovoltaic cell.
The class information and identification symbols of these solar cells can be stored in a storage unit in the control unit 20 of the solar cell inspection apparatus. If the storage capacity becomes large, it may be stored in a separate computer.
The first embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made by those skilled in the art. For example, as one modification, the crack position information generation unit 24 specifies the positions of the cracks 32a, 32b, and 32c by a differential filter. However, the present invention is not limited to this mode. A linear pixel group having a lightness lower than that of the surroundings may be extracted and specified as cracks 32a, 32b, 32c, and the like.
As described above, according to the present embodiment, defects of solar cells can be determined in detail. In addition, it is possible to determine in detail the performance and quality of the solar battery module using the solar battery cells determined for the class.
Since the identification information is marked on the solar cell incorporated in the solar cell module in this way, if a defect such as chipping occurs during its use and the performance deteriorates, the solar cell is inspected. Since the defect determination threshold is known, the result can be fed back to the determination method of the inspection apparatus. For example, if a crack (see 32c in FIG. 5) is later lost during use, the threshold value for defect determination that is currently set is changed (re-adjusted), and this is the case during the next inspection. A defect equivalent to a crack (32c in FIG. 5) can be determined as a defect by a solar cell inspection apparatus. In addition to this, since a lot of information such as changes in defects after the passage of time and differences due to defects in the changes can be collected during use, the accuracy of thresholds, the accuracy of defect determination, etc. can be improved step by step. Can be increased.

The second embodiment is an embodiment provided by adding a preferable configuration to the first embodiment. In the second embodiment, the description of the first embodiment can be omitted as it is.
Since the solar battery cell has a size of 150 mm square, it often has a place where it can be partially used even if there is a defect. Example 2 is a means and method for partially reusing a solar cell when the solar cell can be partially used even if it is entirely defective. In addition, the second embodiment is also a means and method for enabling feedback of the result of actual use of the solar cell module and making the determination of defects in the solar cell inspection apparatus and method more accurate.
FIG. 8 is a block diagram illustrating a functional configuration example of the control unit in the second embodiment, and FIG. 9 is a flowchart illustrating a solar cell inspection method realized in the control unit in the second embodiment. The control unit 20 further includes a defective area determination unit 2B as compared to FIG. 3 of the first embodiment. The defect area determination unit 2B receives the cell image including at least the defect information determined by the defect determination unit 2A, and determines a defective area and a non-existent area of the solar battery cell based on the cell image (S110). .
Specifically, the defect area determination step S110 will be described in detail with reference to the flowchart of FIG. 10 showing the defect area determination method.
A cell image including a dark portion that is regarded as a defect based on the crack determination result in S4 and the dark region determination result in S6 is scanned from one end of the cell to the other end in the direction of the solar cell bus bar by a scanning line or the like. It is moved and scanned, and even if there is one defect at one scanning position, this region is determined as a region having a defect. Furthermore, as a result of scanning, an area having no dark portion is extracted, and this area is determined as an area having no defect (S101). Here, the scanning direction is the bus bar direction. This is because when the solar battery cell is partially reused, the partially reused solar battery cell also has a shape having a bus bar.
However, it may be determined that there is a defect in all areas in the first scan. Therefore, it is determined whether or not there is a portion where the area of the defect-free area exceeds a certain threshold (S102).
Specifically, as a result of the determination, if the area without defects does not exceed the predetermined threshold, the determination threshold for each defect type is changed (readjusted) (S103). Specifically, it is performed as follows. Here, the threshold value set for determining the defect is a threshold value (length, area, etc.) for each defect type. In this way, the dark portion of the entire cell image can be reconstructed by replacing the dark portion with a bright portion for a defect smaller than the threshold value based on a preset threshold value (S104). The cell image obtained by reconstruction is different depending on the threshold value, but when the threshold value is equal to or larger than a certain value, the reconstructed image has a dark area smaller than the original image (cell image received from the defect determination unit 2A). Become.
After the cell image is reconstructed by the above means (S104), the reconstructed cell image is scanned again (S101). As a result, if the area without defects exceeds a certain threshold, the process proceeds to the next stage.
Here, changing the threshold value adjusted in the threshold readjustment step S103 changes the threshold value for each defect type. The threshold value is changed by preferentially changing a crack having a low importance as a defect, and then changing in the order of finger disconnection and finally a chip. A crack is first judged to be a defect, but later it is less important because it may not lead to chipping during use. Since the area of the dark part due to finger breakage is small, the degree of importance is made lower than the chip. Here, the above-mentioned preferential change means that the threshold for determining which type of defect is changed before the threshold for determining other defects. The threshold value for defect determination may be changed by weighting change (change more than other defects). It is also possible to combine and use both the priority change and the weight change.
The threshold value of the area of a defect-free area or the like is preferably about half that of the solar battery cell, but the threshold value can be set as appropriate if it can be determined that it can be reused.
When the area of the defect-free area exceeds the threshold value in the determination of S102, the process proceeds to the next stage, and the defect-free area is specified (S105).
11 and 12 are explanatory diagrams of cell image reconstruction. FIG. 11 shows the first cell image. It is determined that almost all areas are defective areas, and then S101, S102, S103, and S104 are repeated. FIG. 12 shows that about half of the solar cell is a defect-free region (no dark portion). If the threshold value for determining the area and the like of the defect-free area is set to half of the area of the solar battery cell (for example, 50% threshold value), the above-described repeated determination operation (S101 to S104) ends at this point. In FIG. 12, the cracks 32c and 32d determined to be defective in FIG. 11 are deleted.
The cracks 32c and 32d were judged to have no problem at this stage, and the cell image was reconstructed by changing the defect judgment threshold.
Returning to FIG. 8 and FIG. The defective area determination unit 2B generates defect area determination information so as to be output to the marking unit 7 for marking (S110). The determination information of the defect area includes boundary information between the defect area and the defect-free area, identification information indicating that the defect area is defective, class information, solar cell identification symbol information, defect This includes information on defect determination threshold values for determining that a region having no defect exceeds a certain threshold value. The defect area determination information from the defect determination unit 2A, the defect area determination unit 2B, and the quality determination unit 28 of the solar cell inspection apparatus is transferred to the marking unit (S120).
The defect area determination unit 2B outputs the determination information of the defect area to the marking unit 7 provided in the inspection apparatus, and the identification symbol information and the like to be given to the solar battery cell includes the defect determination unit 2A and the quality determination. It can also be transferred from the unit 28 to the marking unit 7.
Moreover, after providing the solar cell with the assigned information such as the identification symbol information and the boundary line information given to the solar cell subjected to the defect inspection by the solar cell inspection device, the solar cell is inspected. You may transfer and memorize | store it in a computer separate from a control part or a test | inspection apparatus. This information can be obtained by using a solar cell built into a solar cell module, if a malfunction such as performance degradation occurs and the solar cell is chipped when the solar cell module is inspected. It is possible to perform feedback management such as which crack in which position of the cell is missing.
FIG. 13 is a diagram showing a light receiving surface (a) and a back surface (b) of a marked solar battery cell. With reference to FIG. 13, the information marked on a photovoltaic cell is demonstrated concretely. First, there are boundary lines 64 and 65 provided as identification lines at the boundary between a region having a defect and a region having no defect. The solar cells are cut along the boundary lines 64 and 65 so that the defect-free region can be reused as a non-defective product. If one boundary line 64, 65 is common with one end of the solar cell in the direction of the bus bar 12, one boundary line can be used.
In addition, in the area with a defect distinguished by the boundary lines 64 and 65, identification symbols 61a and 61b (indicated by x in the drawing) marked to indicate the area having the defect, and the solar battery cell The identification symbols 62a and 62b and the identification symbols 63a and 63b representing the determination class can be marked (see FIG. 13A). In the defect-free region distinguished by the boundary lines 64 and 65, the identification symbol 70 of the solar battery cell, threshold information for determining that there is no defect (the threshold value used for determining YES in S102) An identification symbol 72 representing information) and / or an identification symbol 71 representing class information associated therewith can be marked. The markings are given to the boundary lines 64 and 65 in a linear shape, and the identification symbols 70, 71 and 72 are given using a two-dimensional code such as a QR code.
The combination of the identification symbol 70 of the solar cell, the identification symbol 72 representing the threshold information, and the identification symbol 71 representing the class information indicates that the threshold value can be obtained if a chip occurs during its use. Can do. For example, when it is determined YES at the threshold of 50% in the step of S102, when a certain crack (see 32c and 32d in FIG. 11) later becomes missing during use, the currently determined defect determination When the next threshold value is readjusted and the next inspection is performed, a defect equal to such a crack (32c, 32d) can be determined as a defect to the end by the solar cell inspection apparatus. In addition to this, since a lot of information such as changes in defects and differences due to defects in the changes can be collected after use, the accuracy of the threshold and the accuracy of defect determination can be improved step by step. Can be increased.
The marking operation of these identification lines and identification symbols can be realized by using a known laser irradiation apparatus. Moreover, the marking part which consists of this laser irradiation apparatus can also be provided in the inspection apparatus of the photovoltaic cell of this invention, and can also be installed separately as the marking apparatus outside the inspection apparatus of a photovoltaic cell.
And the marking is preferably on the back electrode 13 side (opposite to the light receiving surface) in FIG. 1B in the case of a non-defective solar battery cell or a region where it is determined that there is no defect. However, in the case of a solar battery cell having a defect, the light receiving surface side in FIG. This is because it is preferable not to perform post-processing to prevent light reception as much as possible on the surface to be reused later. Further, it is preferable to mark the light receiving surface that becomes a conspicuous portion so that the portion that is likely to be discarded later is not mistakenly used as a non-defective product.
According to the embodiment described above, even if there is a defect in one solar battery cell, the reusability (utilization efficiency) is increased because only a part that can be partially used can be used. Further, it becomes possible to carry out a follow-up analysis of defects in the solar battery cells over the course of use, and the accuracy of the defect determination of the solar battery cell inspection apparatus becomes higher.
The present invention is not limited to the first embodiment and the second embodiment, and various modified embodiments can be adopted as a matter of course.
FIG. 14 is a diagram showing a modification of the first embodiment and the second embodiment. As shown in FIG. 14, the marking device 80 may be provided separately outside the solar cell inspection device. In this case, information from the defect determination unit 2A, the defect region determination unit 2B, and the quality determination unit 28 of the solar cell inspection apparatus is transferred to the marking device 80 and marked on the solar cell.
As another modification of Example 1 and Example 2, when it is necessary to wait for a plurality of solar cells that have already been inspected for defects between the solar cell inspection device and the marking device due to the tact time of the production line And the like, only a symbol for identifying the solar cell is given by the marking unit 7 in the solar cell inspection apparatus, and the remaining identification symbols and identification lines (border line between the defect-free region and the defect-free region) The information may be transferred and marked to a marking device 80 outside the solar cell inspection device.
The following embodiments can be adopted as other modifications of the first and second embodiments. For example, only the identification symbol of the solar battery cell is marked, and the determination information of the defect area is stored in a personal computer or the like with electronic information, and after setting the solar battery cell in another processing apparatus, It is also possible to read a given identification symbol, read necessary defect area determination information and boundary line information from a personal computer, and based on that information, the solar cell is cut to remove unnecessary portions. At this time, threshold information for defect determination is marked on the solar cell to be reused. Furthermore, as a method of giving identification information or the like to the solar battery cell, not only laser marking but also identification means such as an RF tag can be adopted. When the RF tag is attached to the solar battery cell, the solar cell identification symbol and the defect area determination information can be stored in the RF tag. Therefore, when a malfunction such as a decrease in performance occurs in a solar battery module incorporating a solar battery cell, the necessary information is obtained from the electronic information of the RF tag attached to the solar battery, and the threshold for determining the defect of the inspection device It is possible to improve the accuracy of defect determination by correcting the determination method.

Claims (24)

1. An image acquisition unit for acquiring a cell image representing a solar cell in an energized state;
   A defect determination unit for determining a defect of a solar battery cell from the solar battery image;
   In a solar cell inspection apparatus including
   A solar cell inspection apparatus including a marking device provided outside the solar cell inspection apparatus for marking at least identification information of the solar battery cell on the solar battery cell.
2. An image acquisition unit for acquiring a cell image representing a solar cell in an energized state;
   A defect determination unit for determining a defect of a solar battery cell from the solar battery image;
   In a solar cell inspection apparatus including
   A solar cell inspection device including a marking portion provided inside the solar cell inspection device for marking at least identification information of the solar cell on the solar cell.
3. An image acquisition unit for acquiring a cell image representing a solar cell in an energized state;
   A defect determination unit for determining a defect of a solar battery cell from the solar battery image;
   In a solar cell inspection apparatus including
   An apparatus for inspecting a solar battery cell, comprising: a marking portion inside the solar cell inspection apparatus and a marking device provided outside the solar cell in order to mark at least solar cell identification symbol information on the solar battery cell.
4. An image acquisition unit for acquiring a cell image representing a solar cell in an energized state;
   It is determined that there is a possibility that a dark area information brighter than a crack and a chip formed by the crack may be a defect by a photographed image of the solar battery cell, and an image obtained by binarizing the photographed image; A defect determination unit that accurately determines a defect by comparing the crack and the dark area information brighter than a chip formed by the crack; and
   Inspecting device for solar battery cell.
5. The solar cell inspection device according to claim 4, further comprising a marking device provided outside the solar cell inspection device to mark at least solar cell identification symbol information on the solar cell.
6. The solar cell inspection device according to claim 4, further comprising a marking portion provided inside the solar cell inspection device to mark at least the solar cell identification symbol information on the solar cell.
7. 5. The solar cell inspection according to claim 4, wherein the solar cell includes an internal marking portion of the solar cell inspection device and a marking device provided outside in order to mark at least the identification information of the solar cell on the solar cell. apparatus.
8. The solar cell inspection apparatus according to any one of claims 1 to 7, wherein the defect determination unit includes at least a crack determination unit that determines a crack and dark area information brighter than a chip caused by the crack.
9. 9. The defect determination unit includes a dark region determination unit that binarizes the captured image of the solar battery cell and determines dark region information of the captured image compared to output information of the crack position information generation unit. The inspection apparatus of the photovoltaic cell described in 1.
10. The solar cell inspection apparatus according to claim 9, further comprising a quality determination unit that determines the quality of the solar cell based on the determination result of the dark region determination unit and the determination result of the crack determination unit.
11. An image acquisition unit for acquiring a cell image representing a solar cell in an energized state;
    A defect determination unit for determining a defect of a solar battery cell from the solar battery image;
    Based on the defect determination result of the solar battery cell, it is possible to determine a region where the solar battery cell has a defect and a region without a defect, and at least identify a boundary between the solar cell with a defect and a region without the defect. A defect region determination unit that generates determination information of a defect region including boundary line information;
    Inspecting device for solar battery cell.
12. The solar cell inspection according to claim 11, further comprising a marking device provided outside the solar cell inspection device for receiving at least a part of the defect region determination information and marking the solar cell. apparatus.
13. The solar cell inspection according to claim 11, further comprising a marking portion provided inside the solar cell inspection apparatus for receiving at least a part of the defect region determination information and marking the solar cell. apparatus.
14. The solar cell according to claim 11, comprising a marking unit provided inside and an external marking device for receiving at least part of the defect area determination information and marking the solar cell. Cell inspection device.
15. The defect area determination information includes at least one of an identification symbol of an area having a defect, class symbol information of an area without a defect, and threshold information of defect determination determined to be an area without a defect. 14. The solar cell inspection apparatus according to any one of claims 14 to 14.
16. The solar cell inspection apparatus according to claim 11, wherein the defect determination unit includes at least a crack determination unit that determines a crack and dark region information brighter than a chip caused by the crack.
17. The defect determination unit includes a dark region determination unit that binarizes the captured image of the solar battery cell and determines dark region information of the captured image compared to output information of the crack position information generation unit. The inspection apparatus of the photovoltaic cell described in 1.
18. The solar cell inspection apparatus according to claim 17, further comprising a quality determination unit that determines the quality of the solar cell based on the determination result of the dark region determination unit and the determination result of the crack determination unit.
19. The solar cell inspection device according to claim 11, wherein a direction of the boundary line is perpendicular to a direction of a bus bar of the solar cell.
20. Obtaining a cell image representing a solar cell in an energized state;
    The step of determining the defect of the solar battery cell by determining that there is a possibility that the image of the solar battery cell may be a defect with dark region information brighter than at least a chip formed by a crank and a crack,
    Comparing the image obtained by binarizing the captured image with the dark region information brighter than the crack and the chipped portion caused by the crack, and determining the dark region by deleting the dark region due to noise;
    A step of determining the quality of the solar battery cell based on the determined defect and the cell image obtained from the dark region.
21. The crystal grain boundary not included in the defect is determined by at least one of the shape of the boundary portion by the crystal grain boundary and the aspect ratio of the shape of the crystal grain boundary in the cell image,
    The dark region due to the finger break included in the defect is determined by at least one of the shape of the boundary portion by the dark region, the shape of the dark region and the brightness of the dark region,
    The solar cell inspection method according to claim 20.
22. In the determination, the cell image including the dark region due to the defect is reconstructed in a cell image in which only the dark portion exceeding the threshold is determined as a defect by using the threshold, and the change of the threshold is repeated until a region having no defect occurs to some extent,
    The method for inspecting a solar battery cell according to any one of claims 20 and 21, wherein identification information such as boundary information between a region without a defect and a region with a defect is generated when a region without a defect is generated to some extent. .
23. The solar cell inspection according to claim 22, wherein the identification display includes at least one of a boundary line between a defect-free region and a region with a defect and an identification symbol corresponding to each region. Method.
24. A process of obtaining a cell image representing a solar cell in an energized state;
    A process for determining a defect from the solar cell image;
    A process of determining a dark area from the captured image;
    A process of scanning a cell image including a dark part due to the defect in a direction perpendicular to the bus bar of the solar battery cell, and determining a region without a defect;
    A recording medium recording a solar cell inspection program for causing a computer to execute the above.

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