JP5271185B2 - Solar power generation device inspection system - Google Patents

Abstract

Disclosed is a low-cost apparatus for inspecting a photovoltaic power generating element, by which a clear captured image can be easily obtained in the inspection of the photovoltaic power generating element, said inspection using an EL method. The apparatus (10) for inspecting the photovoltaic power generating element is provided with: a holding table (14) for the photovoltaic power generating element (12); a power supply (16) which applies a forward bias to the photovoltaic power generating element (12); a camera (18) which captures an image of EL of the photovoltaic power generating element (12); a filter (20) for passing through light having a predetermined wavelength; and a light source (26) which irradiates the photovoltaic power generating element (12) with light that includes light in the near infrared region.

Description

  The present invention relates to a solar cell inspection apparatus using an EL (Electro-Luminescence) method.

  In recent years, in order to promote the use of clean energy, photovoltaic power generation elements have been actively developed and spread. Currently, a silicon crystal solar cell is the most widely used photovoltaic power generation element. In a silicon crystal solar cell, an n layer (about 1 μm) and an antireflection film are sequentially stacked on the light receiving surface side of a P-type silicon wafer of about 0.3 mm. Further, the front electrode and the back electrode are formed by a printing method.

  A solar power generation element is easy to produce various defects at the time of manufacture. For example, (1) silicon wafers are easily cracked or chipped, so that fine cracks are likely to occur during production. (2) Since the electrode pattern is formed by a printing method, and the electrode pattern penetrates the antireflection film and is bonded to the n layer during firing, disconnection of the electrode pattern is likely to occur.

  Therefore, it is necessary to inspect defects during manufacturing. As a defect inspection method, an EL method in which a forward bias is applied to a photovoltaic power generation element is generally used (see the following patent documents and non-patent documents). By applying a forward bias, a near-infrared ray based on a silicon band gap is emitted if it is a silicon-based photovoltaic power generation element. If there is a crack, near infrared rays are not emitted from the cracked part and are observed as a dark part. Further, if the electrode is disconnected, power is not supplied after the disconnection position, so near infrared rays are not emitted after the disconnection position and are observed as a dark part.

  Here, in order to detect fine cracks that cannot be detected by appearance inspection, it is necessary to obtain a clear image with high resolution. In addition, in order to specify the disconnection location, a resolution capable of photographing a thin surface electrode (200 μm) is required.

  For example, assume that a defect inspection is performed on a solar cell panel (1 m × 2 m) on which 50 to 60 photovoltaic power generation elements are mounted. In this case, a forward bias equivalent to the open circuit voltage is applied to each photovoltaic power generation element to emit near infrared rays from the solar cell panel. The emitted photovoltaic power generation element is photographed with a camera, and the presence / absence of a defect and the location of the defect are specified.

  However, a cooled CCD (Charge Coupled Device) camera used for the defect inspection is not equipped with an autofocus mechanism. For this reason, it is necessary to take several images while changing the focal length of the lens little by little, check the image each time, and find a focus position. When there is a change in the size of the subject or the part to be photographed, it is necessary to adjust the focus each time, and it takes time and effort.

  A method of focusing while looking through a viewfinder performed by a general camera can be considered. However, the EL of the silicon-based solar cell is invisible to the naked eye because it is near infrared. As shown in FIG. 2, when the same lens 34 is used for near-infrared rays and visible light, the focal lengths are different, and the near-infrared focal length is increased. Therefore, focusing with visible light and photographing near infrared rays results in a defocused image.

  Even when an autofocus mechanism mounted on the camera is used, since it is premised on photographing with visible light, focusing under visible light photographing conditions is performed. The most commonly used method for measuring the distance to the subject is to measure the distance between the solar panel and the camera, but to adjust the lens to the focal position with visible light. The near-infrared image is out of focus for focusing under visible light shooting conditions.

  A TTL (Through the Lens) phase difference method used for autofocus of a single-lens reflex camera is basically driven under visible light photographing conditions. As described above, the image is out of focus.

  Furthermore, contrast autofocus using the contrast and blur used frequently in digital cameras can operate even in the near infrared. However, since the amount of EL of the photovoltaic power generation element is weak, autofocus cannot be operated. Further, since the light amount of EL is weak, the exposure time required for photographing using a normal camera (non-cooled image sensor) is as long as 10 to 30 seconds. If a special imaging device (cooling type with an amplification function) is used, there is a possibility that the detection sensitivity capable of operating the autofocus mechanism may be satisfied, but it is very expensive.

International Publication Number WO2006 / 059615 International Publication Number WO2007 / 129585 "Observation of Electroluminesce from Amorphous Silicon Solar Cells at room" Koeng Su Lim et al, JapaneseJournal of Applied Physics, Vol.21, No.8, August, 1982 pp.L473-14759

  An object of the present invention is to provide an inexpensive solar power generation element inspection apparatus capable of easily obtaining a clear captured image in an inspection using the EL method of a solar power generation element.

  The photovoltaic power generation element inspection apparatus includes a power source that applies a forward bias to the photovoltaic power generation element, and an automatic focusing mechanism that performs automatic focusing on the photovoltaic power generation element and uses the imaging element to increase the photovoltaic power generation element. A non-cooled image sensor camera that captures the image and a filter that is disposed between the solar power generation element and the image sensor and cuts light below the EL wavelength of the solar power generation element and transmits light in the near-infrared band And a light source for irradiating the solar power generation element with light containing a near-infrared band during the automatic focusing.

  The power source applies a forward bias to the photovoltaic power generation device, and the camera performs automatic focusing and photographing. A filter is provided to remove the influence of visible light or the like and to receive EL light. The light source emits light containing near infrared rays so that the autofocus of the camera is sufficiently driven.

  It includes a dark room in which at least a solar power generation element, an uncooled image sensor camera, a filter, and a light source are arranged. Use a darkroom that eliminates the effects of external light.

  The filter is a shortcut filter that cuts a wavelength of 950 nm or less to 25% or less and a wavelength of 900 nm or less to 5% or less. In this filter, the solar power generation element is a filter of a crystalline silicon solar cell or a chalcopyrite solar cell.

  The filter is a shortcut filter that cuts a wavelength of 750 nm or less to 25% or less and a wavelength of 700 nm or less to 5% or less. The solar power generation element is a filter for an amorphous silicon solar cell or an organic thin film solar cell.

  The light source is a halogen lamp. Lights a halogen lamp during focusing.

  According to the present invention, it is possible to drive autofocus with near-infrared light by removing light having a wavelength less than the EL wavelength of the photovoltaic power generation element using a filter. Quick focusing is possible. Since focusing is performed with near infrared rays, the captured image is also focused with near infrared rays, and the EL light becomes a clear image. It becomes easy to detect the defective part of a photovoltaic power generation element.

It is a figure which shows the structure of the inspection apparatus of a photovoltaic device. It is a figure which shows the difference in the focus by a wavelength.

  The photovoltaic device inspection apparatus of the present invention will be described with reference to the drawings.

  The photovoltaic power generation element to be inspected emits near infrared rays with forward bias in order to use the above-described EL method. For example, a solar cell of crystalline silicon type or amorphous silicon type can be given. The number of photovoltaic power generation elements may be one, or a plurality of photovoltaic power generation elements may be arranged vertically and horizontally.

  As shown in FIG. 1, the photovoltaic power generation element inspection device 10 photographs the holding base 14 of the solar power generation element 12, the power supply 16 that applies a forward bias to the solar power generation element 12, and the EL of the solar power generation element 12. And a filter 20 for transmitting light of a predetermined wavelength.

  The holding table 14 is provided with the solar power generation element 12 and makes the solar power generation element 12 face the camera 18. A mechanism for adjusting the height and angle is provided as appropriate. In addition, the size of the holding table 14 is appropriately designed according to the size of the photovoltaic power generation element 12.

  The power source 16 is a DC power source for applying a forward bias to the photovoltaic power generation element 12. When a plurality of photovoltaic power generation elements 12 are arranged vertically and horizontally, a forward bias is applied to all the photovoltaic power generation elements 12. An example of forward bias is about 0.5-1.0 V per crystalline silicon type photovoltaic power generation element, thin film type amorphous silicon type and compound type chalcopyrite solar cells (CIS, CIGS, etc.) In the tandem type, about 0.5-1.0V per stage, the voltage is adjusted according to the number of layers. By applying a forward bias to the solar power generation element 12, light in the near infrared band is emitted from the solar power generation element 12. For example, the wavelength of the emitted light is about 700 to 1300 nm. The peak wavelengths of the crystalline silicon type are about 1150 nm, the amorphous silicon type is about 950 nm, the CIS is about 1250 nm, and the CIGS differs depending on the composition ratio.

  The camera 18 uses a digital still camera having an autofocus mechanism and an uncooled image sensor 22. The autofocus mechanism is a mechanism that can use a contrast autofocus system. For focusing, a method of moving the lens or a method of moving the holding table 14 can be adopted. The image sensor 22 uses a silicon-based CCD or CMOS two-dimensional image sensor. The number of pixels is appropriately selected according to the size of the photovoltaic power generation element 12. For example, an image sensor 22 having about 10 million pixels is used. The camera 18 is installed on a tripod 24 or the like, and the height and angle are adjusted.

  The filter 20 cuts light having a wavelength less than that of the light generated by the EL of the solar power generation element 12 and transmits light in the near-infrared band. The filter 20 has a sheet shape and is provided between the photovoltaic power generation element 12 and the image pickup element 22 of the camera 18. Therefore, the image sensor 22 does not receive light having an EL wavelength shorter than visible light, such as visible light, and receives near infrared light. The camera 18 can take an image of the EL of the solar power generation element 12 and can perform contrast autofocus using the imaging element 22. Specific installation locations of the filter 20 include the front surface of the image sensor 22 and the front surface of the lens. In FIG. 1, a filter 20 is provided inside the camera 18 and in front of the image sensor 22.

  When the photovoltaic power generation element 12 is a crystalline silicon solar cell or a chalcopyrite solar cell, the filter 20 is a shortcut for cutting a wavelength of 950 nm or less to 25% or less and a wavelength of 900 nm or less to 5% or less. Use a filter. When the solar power generation element 12 is an amorphous silicon solar cell or an organic thin film solar cell, the filter 20 is a shortcut filter that cuts a wavelength of 750 nm or less to 25% or less and a wavelength of 700 nm or less to 5% or less. Is used.

  The filter 20 may be a high-pass filter that transmits light having a wavelength longer than the wavelength of light by the EL. Since the CCD or the like of the image sensor 22 is a silicon-based element, even if light having a wavelength longer than near infrared rays reaches the image sensor 22, it is a transparent region of silicon itself, and therefore absorbs long-wavelength light. There is no. If the wavelength is further longer, it is absorbed by the peripheral members of the image sensor 22 and cannot reach the image sensor 22. Therefore, it is equivalent to cutting light having a wavelength less than EL wavelength such as visible light and transmitting light in the near infrared band.

  As described above, the light received by the image sensor 22 by using the filter 20 becomes near infrared rays. Auto-focus uses near infrared rays. Since the light is in the same band as the photographed light, the photographed image is in focus. The captured image is clear and it becomes easy to detect a defect of the photovoltaic power generation element 12.

  Further, the inspection apparatus 10 includes a light source 26 that irradiates the photovoltaic power generation element 12 with light including a near-infrared band. The light source 26 emits light when the camera 18 performs focusing by an autofocus mechanism. The light source 26 emits light that can be driven by the autofocus mechanism. The camera 18 can secure near infrared rays with a sufficient amount of light for driving autofocus. When photographing the EL of the solar power generation element 12, the light source 26 is turned off. This is because the amount of EL light is small. If the subject is plain and difficult to contrast, it is also useful to attach a focus mark on the surface or project a geometric pattern on the light source 26. A halogen lamp may be used as the light source 26.

  It is also conceivable to use a normal fluorescent lamp or an incandescent bulb as the light source 26 and irradiate the photovoltaic power generation element 12 through a filter that blocks visible light. However, ordinary fluorescent lamps and incandescent lamps have a large amount of visible light and a small amount of near infrared light. Increasing the amount of near-infrared light is not preferable because the amount of visible light becomes very large and incandescent bulbs and filters are damaged in a short time.

  Although the light source 26 in FIG. 1 is provided at a position away from the camera 18, the light source 26 may be built in the camera 18 like an autofocus auxiliary light using a built-in light of a normal camera.

  Further, the inspection apparatus 10 includes a dark room 28 in which at least the photovoltaic power generation element 12, the camera 18, the filter 20, and the light source 26 are disposed. The EL of the solar power generation element 12 is weak, and the dark room 28 removes the influence of light from the outside.

  In addition, a computer 30 that controls the camera 18, the power supply 16, and the light source 26 is provided. The computer 30 includes a monitor 32 that displays the status of the camera 18, the power supply 16, the light source 26, captured data, and a keyboard for operating the computer 30. The computer 30 controls the camera 18, the power supply 16, and the light source 26 collectively. It is possible to easily synchronize the driving of the autofocus mechanism and the light emission of the light source 26, or to synchronize the application of the forward bias by the power supply 16 and the photographing by the camera 18. In addition, the acquired photographing data can be stored in a storage device such as a hard disk of the computer 30. Each of these devices is connected to each other by a USB (Universal Serial Bus) cable or the like. Although the computer 30 and the light source 26 are connected in FIG. 1, the camera 18 and the light source 26 may be directly connected so that the camera 18 and the light source 26 can be synchronized.

  An example and a comparative example for confirming that the inspection apparatus 10 of the present application can easily focus and an image of the solar power generation element 12 is obtained will be described.

Example (1)
The solar power generation element 12 is a polycrystalline silicon type Kyocera solar cell module R150-01, the light source 26 is an IR (infrared) lamp, a Toshiba Lighttech infrared livestock bulb 100 / 110V 150WRE (halogen lamp), and a filter 20 Is Fujifilm optical filter IR-96 (950 nm transmittance 25% or less, 900 nm transmittance 5% or less shortcut type), dark room 28 is a large simple dark room B-L3-CU made by Sun Entex, camera 18 is Sony digital still cameras DSC-H50 were used. Further, the infrared cut filter mounted on the camera 18 was removed, and the filter 20 was mounted on the front surface of the image sensor 22. The camera 18 was shielded from light so as not to be emitted from the autofocus auxiliary light source of the camera 18. In the dark room 28, the camera 18, the solar power generation element 12, and the light source 26 were installed.

  After turning on the light source 26, the camera 18 was set to night shot mode (a state in which contrast autofocus is activated) to perform automatic focusing, and then switched to the manual mode. A forward bias was applied so that a current of 8 A would flow through the solar power generation element 12 to emit EL, and the exposure time was 30 seconds. The photographed image was confirmed on the monitor 32, and the focusability and image quality were judged. By autofocus, the focus was accurate and the details of the surface electrode could be confirmed.

Example (2)
The solar power generation element 12 of Example (1) was changed to an amorphous thin film type made by Solarex, and the filter 20 was an optical filter IR-76 made by Fuji Film (transmittance of 750 nm is 25% or less, and transmittance of 700 nm is 5% or less. Images were taken under the same conditions as in Example (1) except that the type was changed. The focus was accurate and the photographed image was good.

Example (3)
Images were taken under the same conditions as in Example (2) except that the photovoltaic power generation element 12 of Example (2) was changed to a tandem type (two layers of amorphous and microcrystalline). Similar to Example (2), the focus was accurate and the captured image was good.

Example (4)
Images were taken under the same conditions as in Example (1) except that the photovoltaic power generation element 12 in Example (1) was changed to compound type CIS (copper, indium, selenium). The focus was accurate and the photographed image was good.

Example (5)
The photovoltaic power generation element 12 of Example (2) is an organic thin film type P3HT: PCBM poly (3-hexylthiophehe: [6,6] -phenylC61-butyric
Images were taken under the same conditions as in Example (2) except that the acid methyl ester was changed. The focus was accurate and the photographed image was good.

Comparative Example (1)
The light source 26 of Example (2) was not provided, and autofocusing was performed only with the EL light of the solar power generation element 12. However, autofocus did not work. Since only the EL light of the solar power generation element 12 has a small amount of light, the brightness required for the autofocus mechanism to operate cannot be obtained. Auto focus could not be used and shooting was not possible.

Comparative example (2)
The light source 26 of Example (1) was not provided, and autofocusing was performed only with the EL light of the solar power generation element 12. As with Comparative Example (1), autofocus did not work.

Comparative Example (3)
The light source 26 of Example (2) was changed to a fluorescent lamp FLR40SEX-N / M-HG (3-wavelength type) manufactured by NEC, and autofocusing was performed. However, autofocus did not work. In a fluorescent lamp, since the amount of infrared component is small, the brightness required for the autofocus mechanism to operate cannot be obtained.

Comparative Example (4)
The light source 26 of Example (1) was changed in the same manner as in Comparative Example (3) to perform autofocus. However, the autofocus did not operate as in the comparative example (3).

Comparative Example (5)
When the autofocus was performed without providing the filter 20 of Example (1), the autofocus was activated. However, since it stopped at the focusing position with visible light, the photographed image was not in focus and the photographed image became unclear.

Comparative Example (6)
The focusing of Example (1) was performed by a distance measurement method, and autofocusing was performed without blocking the autofocus auxiliary light. The autofocus was activated, but stopped at the focus position with visible light, so the image taken was not in focus and was unclear.

Comparative Example (7)
When the dark room 28 of Example (1) was removed and autofocusing was performed under the condition of a fluorescent lamp, autofocusing was activated. The focus position could be captured without any problem in the focus position. However, some of the reflected images of faint infrared rays emitted from fluorescent lamps were reflected. Although there was noise as an EL image, I was able to shoot

Comparative Example (8)
Photographed under the same conditions as in Example 1 except that the filter 20 of Example (1) was changed to an optical filter IR-76 made by Fuji Film (transmittance of 750 nm 25% or less, 700 nm transmittance 5% or less, shortcut type). . Although the details seemed unclear, the EL could be confirmed.

Comparative Example (9)
Images were taken under the same conditions as in Example 1 except that the photovoltaic power generation element 12 of Example (1) was changed to an amorphous thin film type made by Solarex. The focus was accurate, but the image was dark.

Comparative Example (10)
Images were taken under the same conditions as in Example 1 except that the photovoltaic power generation element 12 of Example (1) was changed to a tandem type (amorphous and microcrystalline two layers). Similar to Comparative Example (9), the focus was accurate, but the captured image was dark.

Comparative Example (11)
Images were taken under the same conditions as in Example (1) except that the photovoltaic power generation element 12 in Example (2) was changed to compound type CIS (copper, indium, selenium). In some cases, the focus was inaccurate, and the laser scribe pattern was sometimes blurred, but EL could be confirmed.

Comparative Example (12)
P3HT: PCBM poly (3-hexylthiophehe: [6,6] -phenylC61-butyric, which is an organic thin film type, is used for the photovoltaic device 12 of Example (1).
Images were taken under the same conditions as in Example (1) except that the acid methyl ester was changed. Similar to Comparative Example (9), the focal point was accurate and the captured image was dark.

  The above examples and comparative examples are summarized in Table 1 below. With the configuration of the present application, autofocus is possible and the image quality of the captured image is good. Inspection of the photovoltaic power generation element 12 using the EL method can be performed smoothly. Since the quality of the captured image is good, it becomes easy to detect a defect of the photovoltaic power generation element 12.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10: Inspection apparatus 12: Solar power generation element 14: Holding stand 16: Power supply 18: Camera 20: Filter 22: Image sensor 24: Tripod 26: Light source 28: Dark room 30: Computer 32: Monitor

Claims (4)

A power source for applying a forward bias to the photovoltaic power generation element;
An uncooled image sensor camera that automatically focuses the solar power generation element by an autofocus mechanism and images the solar power generation element using the image sensor;
A filter that is disposed between the solar power generation element and the imaging element, cuts light below the wavelength of the EL of the solar power generation element, and transmits light in a near-infrared band; and
A light source comprising a halogen lamp for irradiating the solar power generation element with light including a near infrared band during the automatic focusing;
A photovoltaic power generation element inspection apparatus comprising: The inspection apparatus according to claim 1, further comprising a darkroom in which at least the photovoltaic power generation element, the uncooled imaging element camera, the filter, and the light source are arranged. The filter is a shortcut filter that cuts a wavelength of 950 nm or less to 25% or less and a wavelength of 900 nm or less to 5% or less,
The inspection apparatus according to claim 1, wherein the solar power generation element is a crystalline silicon solar cell or a chalcopyrite solar cell. The filter is a shortcut filter that cuts a wavelength of 750 nm or less to 25% or less and a wavelength of 700 nm or less to 5% or less,
The inspection apparatus according to claim 1, wherein the photovoltaic power generation element is an amorphous silicon solar cell or an organic solar cell.

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