Surface inspection device and surface inspection method for protective glass of solar panel

Abstract

In order to provide an inspection device and an inspection method which are suitable for inspecting damage or foreign matter on the surface of a protective glass on the surface of a solar panel, the present invention is configured as follows.　This surface inspection device for a protective glass of a solar panel, having solar cells and the protective glass for protecting the solar cells, comprises: an irradiation optical system which has a light source and a polarizer for polarizing light from the light source, and which irradiates the protective glass with light; and a detection optical system for detecting light reflected from the protective glass, wherein the detection optical system includes at least a lens, a polarizer, a pinhole, and a photodetector which are disposed on the optical path in this order, and in the surface inspection, the lens is installed such that the imaging position on the surface of the protective glass is on the surface of the pinhole.

Description

Surface inspection device and surface inspection method for solar panel protective glass

[0001] The present disclosure relates to inspection of scratches and foreign matter on the surface of a transparent member, and more particularly to a surface inspection device and a surface inspection method for a protective glass for a solar panel.

[0002] In order to achieve a sustainable society, the large-scale introduction of solar power generation as a renewable energy source is progressing, but at the same time, the disposal of solar panels after use is becoming an issue, and there is a growing need for technology to reuse components.

[0003] Solar panels are primarily composed of a metal frame, solar cells, and protective glass to protect the solar cells, with the protective glass glued on top of the solar cells. Currently, only a portion of these components are recycled, and the protective glass in particular is often crushed and then disposed of in landfills. One of the reasons why crushed glass is not reused and is disposed of in landfills is that the price of crushed glass (cullet) is low, and the cost of recycling it is not worth it. In response to this issue, technology has been developed to extract high-quality glass from solar panels without crushing them, making it possible to sell used glass at a price that is worth the cost of recycling.

[0004] However, when solar panels are installed outdoors and exposed to wind, rain, and snow, there is a possibility that the glass on the surface may become scratched, chipped, or have foreign matter attached. Hereafter, such undesirable areas of deterioration will be collectively referred to as defects. Since the number and location of such defects vary depending on the usage environment and the individual product, they must be inspected and the treatment method changed depending on the results.

[0005] For example, if it is determined that there are only a few scratches, it can be reused for furniture, aquariums, etc., which require aesthetic appeal. Alternatively, if it is determined that there are many scratches and it cannot be reused, it can be used as frosted glass for building materials, or for greenhouses, etc., where even minor scratches are not noticeable. Also, if there are too many scratches to reuse it, it can be disposed of by crushing as usual.

[0006] One possible method for inspecting the surface of such solar panel protective glass for scratches and chips is to adapt a technique for inspecting the surface of semiconductor wafers for scratches and defects. Patent Document 1 describes a semiconductor wafer inspection method in which a laser beam is irradiated onto the semiconductor wafer and the laser beam is scattered at the location of the scratches or defects.

[0007] JP 2010-14635 A

[0008] Since defects in the glass on solar panels are thought to occur mainly on the surface exposed to wind and rain, it is necessary to selectively inspect the vicinity of the glass surface rather than the interior or back surface of the glass. However, since the glass on solar panels has structures such as solar cell electrodes on the back surface, there is a concern that if the technology described in Patent Document 1 is adapted, defects may be falsely detected due to light reflected by the electrodes. Furthermore, if the solar cell is made of polycrystalline silicon, there is a possibility that scattered light at the silicon grain boundaries may be falsely detected as scattered light from glass defects.

[0009] An object of the present disclosure is to provide a surface inspection device and a surface inspection method suitable for inspecting scratches and foreign matter on the surface of a protective glass on a solar panel.

[0010] A surface inspection apparatus and a surface inspection method according to one aspect of the present disclosure are as follows.

[0011] A surface inspection device for protective glass for solar panels having a solar cell and protective glass for protecting the solar cell, the surface inspection device comprising: an irradiation optical system having the light source and a polarizer that polarizes light from the light source and that irradiates light onto the protective glass; and a detection optical system that detects light reflected by the protective glass, the detection optical system having at least a lens, a polarizer, a pinhole, and a photodetector, which are arranged in this order on an optical path, and the lens is installed so that, during surface inspection, the position where an image of the surface of the protective glass is formed is on the plane of the pinhole. A surface inspection method for protective glass for solar panels, in which, during inspection, the lens is adjusted so that the surface of the protective glass is positioned so that an image of the surface of the pinhole is formed.

[0012] According to the present disclosure, it is possible to provide a surface inspection device and a surface inspection method suitable for inspecting scratches and foreign matter on the surface of a protective glass on a solar panel.

[0013] Cross-sectional view of an inspection device and a solar panel. A diagram explaining the relationship between the focal length and the distance between optical elements of a detection optical system. A flowchart explaining an inspection procedure. A diagram for defining the angle of incidence of an irradiation optical system. A diagram of an inspection device according to a modified example. A conceptual diagram of irradiation light and detection light in an inspection device according to a modified example. A flowchart explaining an inspection procedure in a modified example. A diagram of an inspection device according to a modified example. A conceptual diagram of an irradiation light source in an inspection device according to a modified example. A diagram of an inspection device according to a modified example. A flowchart explaining an inspection procedure in a modified example.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the contents of the present disclosure are not limited to the embodiments described below, and various modifications are possible within the scope of the technical concept. Furthermore, corresponding parts in each drawing used to describe each embodiment described below will be designated by the same reference numerals, and duplicated explanations will be omitted.

[0015] In this embodiment, the glass on the surface of a solar panel is inspected as an example, but the object is not limited to a solar panel. For example, the glass used on the outside of a refrigerator can also be inspected because it has an opaque material on the back side.

[0016] FIG. 1 is a schematic diagram showing the configuration of an inspection device used in the inspection method of this embodiment.

[0017] The inspection object 1 is composed of a transparent member (glass plate) 1a on the front side and an opaque member 1b made of a solar cell and a metal frame on the back side. The inspection device is composed of an irradiation optical system 2 that irradiates light L1, a detection optical system 3 that detects light L2 emitted from a defect site, and a stage 4 that moves the inspection object 1.

[0018] The irradiation optical system 2 comprises a light source 2a, a lens 2b, and a polarizer 2c. The light source 2a may be a white light source such as an LED or a lamp, or a laser light source that emits light of a single wavelength. In the case of a laser, it may be a continuous wave laser or a pulsed laser. Alternatively, it may be a white laser light source such as supercontinuum light.

[0019] The glass to be inspected is transparent to a wide range of wavelengths from ultraviolet to infrared (there are no specific wavelengths that absorb or reflect light), so a light source of any wavelength can be used, but with visible light, the position of the light irradiation can be confirmed visually, making it easy to adjust the device. Also, as will be described later, when using visible light, inexpensive CCD or C-MOS sensors, Si photodiodes, etc. used in cameras can be used as sensors in the detection optical system, reducing the cost of the entire device.

[0020] Furthermore, visible light has a wavelength that is highly absorbed by the solar panel on the backside, so the reflectance from the backside is low, which is expected to reduce the chance of false detection. Among visible light, blue light is preferable because it has a short wavelength and can detect finer defects. Blue light is light with a wavelength of approximately 430 nm to 490 nm.

[0021] Lens 2b is used to irradiate the light emitted from the light source onto the inspection area of ​​the sample. For example, as shown in Figure 1, the light can be converted into parallel light and then irradiated over a wide area. Irradiating a wide area makes the system robust against misalignment of the optical axis, and reduces the number of times the optical axis needs to be adjusted periodically.

[0022] Alternatively, if it is desired to inspect a narrower area in more detail, multiple lenses may be used to focus the light onto the object to be inspected. When a commonly used circular lens is used, the light is irradiated onto a circular or elliptical area depending on the angle of incidence, but it is also possible to irradiate light in a line shape using a cylindrical lens. An example of using a cylindrical lens will be explained in detail in the modified example.

[0023] The polarizer 2c is used to adjust the polarization plane of the light irradiating the inspection object. When the light source is a non-polarized light source such as an LED, a polarizer can be used as the polarizer, and when the light source is a laser, a wave plate for rotating the polarization plane can be used.

[0024] The direction of polarization can be set arbitrarily, but it is more preferable to use s-polarized light as the polarization plane in order to increase the reflectance on the surface of the transparent member and reduce the amount of light transmitted into the transparent member. Note that when using a laser light source that outputs linearly polarized light and the polarization plane is fixed to s-polarized light, polarizer 2c may be omitted.

[0025] The detection optical system 3 is composed of lenses 3a and 3a', a variable diaphragm 3b, a polarizer 3c, a pinhole 3d, and a light receiving element 3e. Light L2 emitted from the defect site passes through the lens 3a, the variable diaphragm 3b, the polarizer 3c, the lens 3a', and the pinhole 3d in that order, and is detected by the light receiving element 3e.

[0026] The detection optical system 3 is configured to selectively detect only light from defective areas near the surface of the inspection object, and combines a confocal configuration with filtering by a polarizer.

[0027] First, the confocal configuration will be described. The confocal configuration consists of a lens 3a, a variable aperture 3b, a lens 3a', and a pinhole 3d. Confocal is a method that can selectively detect only the light emitted from the focal position of the lens 3a by projecting the focal point of the lens 3a onto the pinhole 3d and detecting only the light that passes through the pinhole. In other words, the detection optical system of this embodiment is an optical system with a shallow depth of field that visualizes only the vicinity of the surface of the inspection object.

[0028] The positional relationship of each component required to achieve such a confocal configuration will be explained using Figure 2. For the sake of explanation, let the focal length of lens 3a be f and the focal length of lens 3a' be f'. In this case, the distance between lens 3a and the surface of transparent member 1a is adjusted to be f. Since the light between lenses 3a and 3a' is parallel, the distance can be set arbitrarily, but it is desirable to make it as short as possible, as this makes adjustment easier and reduces the size of the device. Let the distance between lens 3a' and pinhole 3d be f'.

[0029] To selectively inspect only defect sites near the surface, the relationship between the depth of field of the entire optical system and the thickness of the transparent member is important. For example, even in a confocal optical system, if the depth of field is deep, light generated from outside the focus will pass through the pinhole, and the selectivity expected in this example will not be obtained, so an adjustment to make the depth of field shallower is necessary.

[0030] The depth of field in a confocal configuration is approximately ±0.7λ / NA from the focal position, although this varies slightly depending on the definition, where NA is the numerical aperture of the optical system and λ is the wavelength. ２ Therefore, to make the depth of field shallower, the NA should be increased. The NA can be written as NA = sin α using the divergence angle α of the light beam in Figure 2. Now, α = tan －１ Since it is (D / 2f), the adjustment to make the depth of field shallower can be achieved by adjusting D or f.

[0031] In the first embodiment, an example of adjusting the NA using the variable aperture 3b is shown, but it is also possible to use a composite lens made up of multiple lenses as the lens 3a and adjust the focal length f.

[0032] Next, a filtering method using polarizer 3c will be described. Light scattered at a defect site is repeatedly diffused at the interface with the glass before being emitted, and is therefore characterized by a change in polarization plane different from that of light reflected on a smooth surface. Therefore, by adjusting the polarizer so that it transmits light at a 90-degree angle to the polarization plane of the incident light, it is possible to extract only the polarization component that has changed at the defect site. For example, if the polarization of the incident light is s-polarized, it is recommended to adjust the polarizer to p-polarized. By detecting only a specific polarization plane in this way, the difference between the defect site and a smooth surface can be more clearly detected, thereby enabling highly sensitive inspection.

[0033] The polarizer 3c is inserted between the lenses 3a and 3a'. In this configuration, the light beams between the lenses 3a and 3a' are parallel, so the insertion of the polarizer does not cause a shift in focus, resulting in a clearer image. The polarizer 3c and the variable diaphragm 3b may be arranged in any order, but it is preferable to arrange the variable diaphragm 3b on the lens 3a side, as this allows for inspection that is more robust against noise caused by stray light, etc.

[0034] The light receiving element 3e may be a light receiving element such as a Si photodiode, etc. A Si photodiode is desirable because it has sufficient sensitivity in the wavelength range of visible light that is the target of this embodiment and can be realized inexpensively.

[0035] The stage 4 is a movable stage used to move the inspection range of the inspection object within the XY plane.

[0036] The inspection method in this embodiment will be described with reference to the flowchart shown in FIG.

[0037] First, the object to be inspected is placed on a stage (S1). Next, the angle of incidence of the first light is set (S2). The angle of incidence is the angle θi with respect to the vertical direction (Z direction) of the surface of the object to be inspected, as shown in FIG. 4. As explained as the problem to be solved by the present invention, when light passes through the front surface and reaches the back surface, the possibility of false detection of a defective portion increases due to scattered light or reflected light from solar cell wiring or the like on the back surface. Therefore, it is desirable to adjust the angle of incidence so that the transmittance is as low as possible (the reflectance is as high as possible). A large angle of incidence θi is desirable because it increases the reflectance on the surface.

[0038] Specifically, an incident angle of 50 to 85 degrees is preferable. This is because, when the incident angle is smaller than 50 degrees, more than 90% of the light is transmitted through the surface, increasing the possibility of false detection of defective areas due to scattered light or reflected light from the solar cell wiring on the back surface, as mentioned above. On the other hand, when the incident angle approaches 90 degrees, the irradiation optical system becomes almost parallel to the object to be measured, making installation difficult, so it is desirable that the incident angle be smaller than 85 degrees. Furthermore, an incident angle between 80 and 85 degrees is more preferable because it allows the reflectance on the surface to be 50% or more.

[0039] Next, the focus is adjusted (S3). As already explained, the detection optical system has a confocal configuration, so it selectively detects light generated at the focal position of lens 3a. Therefore, the distance between the detection optical system and the object to be inspected is adjusted so that the surface of the transparent member is at the focal point of lens 3a. The distance can be adjusted by moving the entire optical system, or by moving only lens 3a. Alternatively, the stage 4 can be a three-axis stage that can move in the X, Y, and Z directions, and adjustment can be made by moving it in the Z-axis direction.

[0040] Next, the numerical aperture is adjusted to set the depth of field to an appropriate value (S4). A shallow depth of field makes it easier to distinguish from scattered light from the solar cell attached to the back surface of the glass, but conversely, if it is too shallow, it becomes difficult to detect deep scratches on the surface. Therefore, there is an optimal value for the depth of field depending on the thickness t of the transparent member.

[0041] In particular, 0.7λ / NA ２ < t, it is advisable to adjust the NA as low as possible (so as to increase the depth of focus). Note that in this embodiment, the NA is adjusted by a variable diaphragm, so adjusting the numerical aperture specifically means adjusting the variable diaphragm.

[0042] Once the optical system adjustment is complete, actual measurement is performed. Measurement involves moving the stage (S5), measuring the signal amount (S6), and if the measured signal amount is equal to or greater than a set threshold, recording the coordinates (x, y) at that time (S7, S8). This is a series of steps that are repeated. Once the measurement of the entire measurement object is complete, the measurement is completed and the inspection object is removed (S10).

[0043] Although this embodiment shows an example in which only the coordinates exceeding a specified threshold are recorded and only the position distribution of the defect locations is output, it is also possible to simply obtain the signal amount as a function of the coordinates (x, y) and finally output a monochrome image corresponding to the signal intensity. When a monochrome image is output, the type, shape, and size of the defect can be analyzed by image processing, pattern recognition, etc., which has the effect of enabling more advanced judgment of whether the glass can be reused and where it can be reused.

[0044] The second embodiment differs from the first embodiment mainly in that the stage 4 is configured by a belt conveyor 4'.

[0045] An example of the inspection device used in this embodiment will be described using Figures 5A and 5B. Figure 5A is a cross-sectional view of the inspection device used in this modified example. Figure 5B is a top view of the light irradiation area L1a and the inspection area L2a in this modified example. Since the basic configuration is the same as in Example 1, only the differences will be described.

[0046] A composite member is placed on a belt conveyor 4' as the inspection object 1, and the belt conveyor can move the inspection object in the X-axis direction. The illumination optical system irradiates a linear illumination range L1a parallel to the Y-axis. For example, if a line generator lens is used for lens 2b', it is possible to illuminate a line of light at once. In this way, an optical system using a line generator lens does not require the addition of a moving mechanism, which has the effect of reducing the influence of vibrations caused by the moving mechanism.

[0047] However, when a line generator is used, the amount of light irradiated per unit area decreases, and the amount of signal obtained may be insufficient. In such cases, a movable mechanism for moving the irradiation optical system in the Y-axis direction or a mechanism for scanning the irradiation position in the Y-axis direction using a mirror may be additionally provided, and light may be irradiated in a spot shape as in Example 1.

[0048] The detection optical system is additionally provided with a movable mirror 3f on the optical path, and the Y coordinate of the object to be inspected, imaged on the pinhole, moves according to the angle of the movable mirror, so that the position detection position of the inspection area L2a can be scanned in the Y direction. When a movable mirror is used, a high-speed galvanometer scanner or the like can be used, which has the effect of enabling high-speed inspection.

[0049] For example, it is possible to scan the inspection range in the Y direction while moving the belt conveyor at a constant speed, thereby shortening the overall inspection time. Alternatively, the entire optical system may be scanned in the Y-axis direction without adding the movable mirror 3f.

[0050] An overview of the inspection device used in such an example is shown in Figures 7A and 7B. Figure 7A is a cross-sectional view of the inspection device in the XZ plane, and Figure 7B is a cross-sectional view of the inspection device in the YZ plane. In the example of Figure 7, the detection optical system 3 is fixed to a movable mechanism 6 in the Y-axis direction, and the entire detection optical system 3 moves in accordance with the movement of the movable mechanism. This makes it possible to scan the detection range in the Y-axis direction. When a movable mirror is used, there are limitations on the size of the composite component that can be inspected due to the movable range of the mirror and the diameter of the lens. However, using a movable stage eliminates these limitations and is therefore more suitable for inspecting large components such as solar panels.

[0051] The inspection procedure in Example 2 will be described with reference to FIG. 6. Steps S1 to S4 are the same as those in Example 1, and therefore a description thereof will be omitted. In this modified example, movement in the X-axis direction is performed by a belt conveyor, and scanning in the Y-axis direction is performed on the optical system side; the inspection object is placed on the belt conveyor in step S1', the belt conveyor is moved in S5', and the mirror angle is scanned in steps S5" and S9'. The measurement method at each coordinate (S7, S8) is the same as that described in Example 1, and therefore a description thereof will be omitted.

[0052] Using a belt conveyor in this way allows for automatic in-line inspection, which has the effect of efficiently inspecting large volumes of discarded solar panels and quickly sorting them according to the presence or absence of defects and the quantity.

[0053] The third embodiment differs from the first embodiment mainly in that the anti-reflection film on the surface of the solar panel is simultaneously inspected.

[0054] First, we will explain the importance of inspecting the anti-reflective coating on solar panels when it comes to reuse. An anti-reflective coating is a surface film that prevents the reflection of light of a specific wavelength. In the case of solar panels, the wavelength range is adjusted to match the performance of the solar cell and the spectrum of sunlight in order to increase the efficiency of solar energy utilization.

[0055] When reusing glass on solar panels, the performance evaluation of the anti-reflective coating is important because it can be sold at a higher price depending on whether the anti-reflective coating has deteriorated. For example, an anti-reflective coating can be expected to reduce glare when observing the inside of a solar panel from the outside or taking photographs. This allows the glass to be reused for applications requiring higher aesthetics and transparency, such as aquariums and display cases, thereby increasing the profitability of glass recycling. However, the method of measuring scattered light generated from defects such as scratches, as described in Example 1, has the problem that it is difficult to measure when the anti-reflective coating has peeled off over a wide area, exposing the smooth surface of the glass.

[0056] The configuration of an inspection device used in Example 3 to address this issue will be described with reference to Figure 8. The inspection device additionally includes a reflection detection optical system 5 that detects reflected light L3. The wavelength of the light source 2a is in the wavelength range of the anti-reflection coating. When such a light source is used, the reflectance is low in areas where the anti-reflection coating is not deteriorated and high in areas where the anti-reflection coating is deteriorated. Therefore, it is possible to determine whether the anti-reflection coating has deteriorated based on the change in the signal from the reflection detection optical system 5.

[0057] The wavelength range of the anti-reflection film can be measured separately by measuring the reflection spectrum, etc. It is not necessary to measure the wavelength range for all panels, and for example, in the case of solar panels and the like discharged from a large-scale solar power plant, they are often standardized to the same model number, so it is sufficient to perform a random inspection only once at the beginning and replace the light source 2 a with a light source of an appropriate wavelength as necessary.

[0058] Another possible method for determining the wavelength range of an anti-reflective coating is to use a camera to determine the color of the glass. Glass with an anti-reflective coating appears colored in the complementary color of the wavelength range of the anti-reflective coating, so it can be determined by measuring the color of the glass surface using a camera or similar device. When using a camera, for example, a camera installed in a smartphone can be used for determination, which has the advantage of allowing for random inspection without the need for additional equipment.

[0059] Alternatively, it is possible to continue using a specific light source without changing it depending on the measurement results. This is because solar panels use anti-reflection coatings in the visible region, such as green, which has the strongest intensity in the solar spectrum, so fixing a green or white light source from the beginning can be sufficient for most cases. In particular, using a white light source is desirable because it allows one light source to be used for many types of solar panels, regardless of the type of anti-reflection coating.

[0060] Next, the configuration of the reflection detection optical system 5 will be described. The reflection detection optical system 5 is composed of at least a light receiving element 5b, and in this embodiment, it additionally includes a lens 5a. The lens 5a focuses reflected light L3 of light L1 incident on the sample onto the light receiving element 5b. By focusing light using a lens, it is possible to detect more reflected light, thereby obtaining a clearer signal and achieving an inspection that is robust against noise. However, although an example using the lens 5a was shown in Example 3, if the size of the light receiving surface of the light receiving element is sufficiently large compared to the size of the reflected light L3, the lens 5a is not necessary.

[0061] Furthermore, the reflection detection optical system 5 may be provided with an additional lens and pinhole, and may have a confocal configuration similar to that of the detection optical system 3. By configuring the reflection detection optical system 5 as a confocal configuration, it is possible to reduce the likelihood of false detection of fluctuations in reflectance due to solar cells or wiring on the back surface of the glass.

[0062] Next, the inspection procedure in Example 3 will be described with reference to Figure 9. Steps S1 to S8 are the same as those in Example 1, and therefore description thereof will be omitted. Example 3 adds step S6' for measuring the signal amount of the reflection detection optical system. As already explained, the reflectance of light increases in areas where the anti-reflection coating is deteriorated, so if the signal amount of the reflection detection optical system is equal to or greater than a threshold value, it is determined that the anti-reflection coating is deteriorated and the coordinates are recorded (S6', S7').

[0063] By simultaneously evaluating the reflectance fluctuation in this way, it is possible to simultaneously inspect not only flaws and other defects that can be identified by scattered light, but also smooth defects that are difficult to identify by scattered light.

[0064] The present disclosure is not limited to the above-described examples and includes various modifications. For example, the above-described examples have been described in detail to clearly explain the present disclosure, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one example with the configuration of another example or modification, and it is also possible to add the configuration of another example or modification to the configuration of one example. Furthermore, it is possible to add, delete, or replace part of the configuration of each example with other configurations.

[0065] 1: Inspection object 2: Irradiation optical system 3: Detection optical system 4: Stage 5: Reflection detection optical system S: Inspection procedure L: Light beam

Claims

1. A surface inspection device for protective glass for solar panels having a solar cell and a protective glass for protecting the solar cell, comprising: an irradiation optical system having the light source and a polarizer that polarizes the light from the light source and irradiates the protective glass with light; and a detection optical system that detects the light reflected by the protective glass, wherein the detection optical system has at least a lens, a polarizer, a pinhole, and a photodetector, and is arranged in this order on the optical path, and wherein the lens is positioned so that, during surface inspection, the position where the image of the protective glass surface is formed is on the plane of the pinhole.

2. In the surface inspection device for a protective glass for a solar panel according to claim 1, the numerical aperture of the detection optical system is NA, the wavelength is λ, and the thickness of the transparent member is t, and the numerical aperture is 0.7λ / NA. ２ a variable diaphragm for adjusting the angle so that t<t is provided between the lens and the polarizer of the detection optical system.

3. A surface inspection device for protective glass for solar panels according to claim 1, characterized in that the angle of incidence when light is irradiated from the irradiation optical system onto the protective glass is between 50 degrees and 85 degrees.

4. A surface inspection device for protective glass for solar panels as described in claim 1, comprising a moving stage for moving the solar panel protective glass to be inspected in two dimensions, and a memory means for storing the coordinates of the surface of the solar panel protective glass in association with the detection results detected by the detection optical system.

5. A surface inspection device for protective glass for solar panels according to claim 1, characterized in that the irradiation optical system irradiates line-shaped light, and the device is provided with a moving stage that moves the solar panel protective glass to be inspected in a direction approximately perpendicular to the line-shaped light.

6. A surface inspection device for protective glass for solar panels according to claim 5, characterized in that the detection optical system is provided with a scanning mechanism for scanning the detection range in a direction generally parallel to the line-shaped light.

7. A surface inspection device for protective glass for solar panels according to claim 1, further comprising a second detection optical system installed at an angle different from that of the detection optical system with respect to the surface of the protective glass for solar panels to be inspected.

8. A surface inspection device for protective glass for solar panels according to claim 1, characterized in that the polarization plane of the polarizer of the irradiation optical system is s-polarized light, and the polarization plane of the polarizer of the detection optical system is p-polarized light.

9. A surface inspection device for solar panel protective glass as claimed in any one of claims 1 to 8, characterized in that the device is provided with an output means for outputting the coordinate position of a defect on the surface of the solar panel protective glass to be inspected, based on the measurement results from the detection optical system.

10. The surface inspection device for protective glass for solar panels according to claim 9, further characterized in that the output means has a function of outputting at least one of information on the shape, size and type of a defect present at the coordinate position.

11. The surface inspection device for a protective glass for a solar panel according to claim 9, further characterized in that the output means outputs whether or not the coating on the surface of the protective glass for a solar panel has deteriorated.

12. A surface inspection method for protective glass for a solar panel having a solar cell and a protective glass for protecting the solar cell, comprising: an irradiation optical system having a light source that irradiates light onto the protective glass and a polarizer that polarizes the light from the light source; and a detection optical system that detects light reflected from the protective glass when the light from the irradiation optical system is irradiated onto the protective glass, wherein the detection optical system uses an inspection device in which at least a lens, a polarizer, a pinhole, and a photodetector are arranged in this order; and the lens is adjusted during inspection so that the surface of the protective glass is imaged onto the plane of the pinhole.

13. A surface inspection method for a solar panel protective glass according to claim 12, wherein the inspection device further comprises a variable diaphragm between the lens and the polarizer of the detection optical system, and when the numerical aperture of the detection optical system is NA, the wavelength is λ, and the thickness of the transparent member is t, the numerical aperture during inspection is 0.7λ / NA ２ The surface inspection method for a protective glass for a solar panel, comprising adjusting the variable diaphragm so that t<t.

14. A surface inspection method for protective glass for solar panels as described in claim 12, characterized in that the inspection device further comprises a moving stage for moving the solar panel protective glass to be inspected in two dimensions, and as a result of inspection by the inspection device, the coordinates of the surface of the solar panel protective glass are linked to the detection results detected by the detection optical system and stored in a memory device.

15. A surface inspection method for protective glass for solar panels as described in claim 12, characterized in that the irradiation optical system of the inspection device irradiates line-shaped light, and further includes a moving stage that moves the solar panel protective glass to be inspected in a direction approximately perpendicular to the line-shaped light, and the inspection is performed by moving the moving stage during inspection.

16. A surface inspection method for protective glass for solar panels as described in claim 15, characterized in that the detection optical system of the inspection device is equipped with a scanning mechanism that scans the detection range in a direction approximately parallel to the line-shaped light, and the inspection is performed by scanning the scanning mechanism during inspection.

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