Method and apparatus for evaluating solar cell

Abstract

To evaluate a degree of deterioration of a solar cell non-destructively.SOLUTION: A solar cell deterioration evaluation device 1 for evaluating a degree of deterioration of a solar cell 100 having a power generation element 101 for generating power in response to emitted light 2, and a protective layer 110 which is laminated on the power generation element 101 and protects the power generation element 101 includes: an irradiation part 10 for emitting light 2 from a light source 11; a detection part 30 for detecting light 3 reflected from the solar cell 100; a calculation part 40 for calculating an index 50 indicating surface roughness of the solar cell 100 on the basis of the light 3 which is detected by the detection part 30 and reflected from the solar cell 100; and a determination part 60 for determining a degree of deterioration of the solar cell 100 on the basis of an index 50 indicating the surface roughness calculated by the calculation part 40.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for evaluating a solar cell, for example, a method and an apparatus for nondestructively evaluating the degree of deterioration of a solar cell.

Background Art

[0002] Generally, a solar cell has a cell as a main body part that generates electric power in response to irradiated light, and a protective layer laminated on the cell to protect the cell. The protective layer is formed of a material with high transmittance such as glass or plastic. The reason why a material with high transmittance is used for the protective layer of the solar cell is to prevent a decrease in the conversion efficiency (power generation efficiency) of the solar cell by preventing a decrease in the amount of sunlight transmitted through the protective layer.

[0003] The protective layer of the solar cell may have a decrease in light transmittance due to dirt adhering to the surface or deterioration due to irradiation with ultraviolet rays. A decrease in the transmittance of the protective layer is a factor in the decrease in the conversion efficiency (power generation efficiency) of the solar cell.

[0004] Conventionally, as a method for diagnosing the presence or absence of deterioration over time of a resin molded product, a method for diagnosing the degree of deterioration of the mechanical properties of an outdoor-exposed resin molded product is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, as a method for evaluating the degree of deterioration of a solar cell, a method for evaluating a decrease in the transmittance of a protective layer is not known. On the other hand, it is also possible to evaluate a decrease in the transmittance of the protective layer of a solar cell by the method disclosed in Patent Document 1 described above. However, when using this method, since it is necessary to irradiate the protective layer with light and detect the light transmitted through the protective layer on the side opposite to the irradiation surface of the protective layer, an operation of cutting out the protective layer from the solar cell is required, and there is a problem that non-destructive evaluation of the solar cell cannot be performed.

[0007] The present invention has been made in view of the above problems, and an object thereof is to evaluate the degree of deterioration of a solar cell non-destructively.

Means for Solving the Problems

[0008] A method for evaluating the degree of deterioration of a solar cell according to a typical embodiment of the present invention is a method for evaluating the degree of deterioration of a solar cell having a power generation element that generates electric power in response to irradiated light and a protective layer laminated on the power generation element for protecting the power generation element, the method including: a first step of irradiating light from a light source toward the solar cell; a second step of detecting light reflected from the solar cell; a third step of calculating an index indicating the surface roughness of the solar cell based on the detected light reflected from the solar cell; and a fourth step of determining the degree of deterioration of the solar cell based on the calculated index indicating the surface roughness.

Effects of the Invention

[0009] According to the present invention, it becomes possible to evaluate the degree of deterioration of a solar cell non-destructively.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 5

Figure 6A

Figure 6B

Embodiments for Carrying Out the Invention

[0011] 1. Outline of the Embodiment First, an outline of typical embodiments of the invention disclosed in the present application will be described. In the following description, as an example, the reference numerals in the drawings corresponding to the components in each embodiment are described with parentheses.

[0012] [1] A method for evaluating the degree of degradation of a solar cell (100) according to an aspect of the present invention includes a power generation element (101) that generates electric power in response to irradiated light (2), and a protective layer (110) laminated on the power generation element (101) for protecting the power generation element (101). The method for evaluating the degree of degradation of the solar cell (100) includes: a first step (step S1) of irradiating the solar cell (100) with light (2) from a light source (11); a second step (step S2) of detecting light (3) reflected from the solar cell (100); a third step (step S3) of calculating an index (50) indicating the surface roughness of the solar cell (100) based on the detected light (3) reflected from the solar cell (100); and a fourth step (steps S4, S5, S6) of determining the degree of degradation of the solar cell (100) based on the calculated index (50) indicating the surface roughness.

[0013] [2] In the method for evaluating the degree of degradation of the solar cell (100) described in [1] above, the index (50) indicating the surface roughness preferably includes the maximum height.

[0014] [3] In the method for evaluating the degree of degradation of the solar cell (100) described in [1] or [2] above, the index (50) indicating the surface roughness preferably includes the arithmetic mean height.

[0015] [4] In the method for evaluating the degree of degradation of the solar cell (100) described in any one of [1] to [3] above, the index (50) indicating the surface roughness preferably includes the arithmetic mean curvature of the peak points.

[0016] [5] In the method for evaluating the degree of degradation of the solar cell (100) described in any one of [1] to [4] above, the index (50) indicating the surface roughness preferably includes the developed area ratio of the interface.

[0017] 〔6〕In the method for evaluating the degree of degradation of the solar cell (100) according to any one of 〔1〕to 〔5〕above, it is preferable that the fourth step (step S4A) includes steps (steps S5, S6) for determining that the higher the degree of degradation, the smaller the index (50) indicating the surface roughness.

[0018] 〔7〕In the method for evaluating the degree of degradation of the solar cell (100) according to 〔1〕above, the index (50) indicating the surface roughness preferably includes the aspect ratio of the surface property.

[0019] 〔8〕In the method for evaluating the degree of degradation of the solar cell (100) according to 〔1〕or 〔7〕above, it is preferable that the fourth step (step S4B) includes steps (steps S5, S6) for determining that the higher the degree of degradation, the larger the index (50) indicating the surface roughness.

[0020] 〔9〕A method for evaluating the degree of degradation of the solar cell (100) according to any one of 〔1〕to 〔8〕above, wherein it is preferable that the first step includes a step of irradiating light (2) toward the solar cell (100) through a slit member (20) having a slit (202) in the shape of a stripe pattern.

[0021] 〔10〕A method for evaluating the degree of degradation of a solar cell (100) according to an aspect of the present invention includes a power generation element (101) that generates electric power in response to irradiated light (2), and a protection layer (110) laminated on the power generation element (101) for protecting the power generation element (101). The method for evaluating the degree of degradation of the solar cell (100) includes: a first step (step S1) of irradiating the solar cell (100) with light (2) from a light source (11) via a slit member (20) having a slit (202) in a stripe pattern; a second step (step S2) of detecting the light (3) reflected from the solar cell (100); a third step (step S3) of calculating the distortion of a slit image (21) formed based on the detected light (3) reflected from the solar cell (100); and a fourth step (steps S4, S5, S6) of determining the degree of degradation of the solar cell (100) based on the calculated distortion.

[0022] 〔11〕An apparatus (1) for evaluating the degree of degradation of a solar cell (100) according to an aspect of the present invention includes a power generation element (101) that generates electric power in response to irradiated light (2), and a protection layer (110) laminated on the power generation element (101) for protecting the power generation element (101). The apparatus (1) for evaluating the degree of degradation of the solar cell (100) includes: an irradiation unit (10) that irradiates the solar cell (100) with light (2) from a light source (11); a detection unit (30) that detects the light (3) reflected from the solar cell (100); a calculation unit (40) that calculates an index (50) indicating the surface roughness of the solar cell (100) based on the light (3) reflected from the solar cell (100) detected by the detection unit (30); and a determination unit (60) that determines the degree of degradation of the solar cell (100) based on the index (50) indicating the surface roughness calculated by the calculation unit (40).

[0023] 〔12〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in the above

[11] , the index (50) indicating the surface roughness preferably includes the maximum height.

[0024] 〔13〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in the above

[11] or

[12] , the index (50) indicating the surface roughness preferably includes the arithmetic mean height.

[0025] 〔14〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in any one of the above

[11] to

[13] , the index (50) indicating the surface roughness preferably includes the arithmetic mean curvature of the peak points.

[0026] 〔15〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in any one of the above

[11] to

[14] , the index (50) indicating the surface roughness preferably includes the developed area ratio of the interface.

[0027] 〔16〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in any one of the above

[11] to

[15] , it is preferable that the determination unit (60) determines that the degree of degradation is higher as the index (50) indicating the surface roughness is smaller.

[0028] 〔17〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in the above

[11] , the index (50) indicating the surface roughness preferably includes the aspect ratio of the surface property.

[0029] 〔18〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in the above

[11] or

[17] , it is preferable that the determination unit (60) determines that the degree of degradation is higher as the index (50) indicating the surface roughness is larger.

[0030] 〔19〕In the apparatus (1) for evaluating the degree of degradation of the solar cell (100) described in any one of the above

[11] to

[18] , the apparatus further includes a slit member (20) having a slit (202) in a stripe pattern shape that blocks a part of the light (2) irradiated from the irradiation unit (10) and allows a part to pass through, and it is preferable that the solar cell (100) is irradiated with the light (2) through the slit member (20).

[0031]

[20] An apparatus (1) for evaluating the degree of degradation of a solar cell (100) according to an aspect of the present invention includes a power generation element (101) that generates electric power in response to irradiated light (2), and a protective layer (110) laminated on the power generation element (101) for protecting the power generation element (101). The apparatus (1) for evaluating the degree of degradation of the solar cell (100) includes an irradiation unit (10) that irradiates light (2) from a light source (11), a slit member (20) having a slit (202) in a stripe pattern shape that blocks a part of the light (2) irradiated from the irradiation unit (10) and allows a part to pass through, a detection unit (30) that detects the light (3) reflected from the solar cell (100), a calculation unit (40) that calculates the distortion of a slit image (21) formed based on the light (3) reflected from the solar cell (100) detected by the detection unit (30), and a determination unit (60) that determines the degree of degradation of the solar cell (100) based on the distortion of the slit image (21) calculated by the calculation unit (40).

[0032] 2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are assigned to the common components in each embodiment, and the repeated description will be omitted. It should be noted that the drawings are schematic, and it is necessary to pay attention to the fact that the dimensional relationships and ratios of the respective elements may be different from the actual ones. There may also be portions where the dimensional relationships and ratios are different between the drawings.

[0033] <<Embodiments of the Present Invention>> FIG. 1 is a diagram showing a schematic configuration of an apparatus for evaluating the degree of degradation of a solar cell according to an embodiment of the present invention.

[0034] The apparatus 1 for evaluating the degree of degradation of the solar cell shown in the figure (hereinafter, also referred to as the "solar cell degradation evaluation apparatus 1") is an apparatus for non-destructively evaluating the degree of degradation of the solar cell. The configuration of the sunlight degradation evaluation apparatus 1 will be described later.

[0035] The solar cell 100 to be evaluated by the solar cell degradation evaluation device 1 is not particularly limited. For example, it has a power generation element 101 that generates electric power in response to irradiated light, and a protective layer 110 laminated on the power generation element 101 to protect the power generation element 101. The power generation element 101 is configured to include, for example, a semiconductor element capable of generating electric power from light by utilizing the photovoltaic effect. The protective layer 110 is formed of a material with a high light transmittance, such as glass or resin (plastic). In the following description, as an example, it is assumed that the solar cell 100 is a flexible solar cell having a protective layer 110 formed of a transparent resin. However, the content described in the following description does not prevent its application to solar cells other than flexible solar cells, for example, solar cells in which the protective layer 110 is formed of a glass material.

[0036] As described above, generally, the protective layer of a solar cell causes a decrease in the light transmittance due to dirt adhering to the surface, degradation due to ultraviolet irradiation, etc., which becomes a factor in the decrease in the conversion efficiency (power generation efficiency) of the solar cell. In particular, for a solar cell having a protective layer formed of resin, the resin as the protective layer is degraded by ultraviolet rays contained in sunlight, and the decrease in light transmittance becomes significant.

[0037] FIG. 2 is a diagram showing the appearance of the surface of a solar cell having a protective layer formed of resin.

[0038] In FIG. 2(a), an image of the appearance of the surface of a solar cell in a state where the protective layer (resin) has not deteriorated is shown, and in FIG. 2(b), an image of the appearance of a solar cell in a state where the deterioration of the protective layer (resin) has progressed is shown.

[0039] As can be understood from FIG. 2, in a solar cell in which the protective layer is not deteriorated, the shape, pattern, etc. of the formed power generation element are clearly shown, while in a solar cell in which the protective layer is deteriorated, the shape, pattern, etc. of the formed power generation element are not clearly shown. The inventor of the present application considered that the difference between FIGS. 2(a) and 2(b) is due to the difference in the reflection of light from the surface of the solar cell. Hereinafter, it will be described in detail with reference to FIGS. 3A to 3C.

[0040] FIG. 3A is a diagram showing an image of reflected light in a solar cell in which the protective layer is not deteriorated. FIG. 3B is a diagram showing an image of reflected light in a solar cell in which the protective layer is deteriorated. FIG. 3C is a diagram showing an image of reflected light in a solar cell in which the deterioration of the protective layer has progressed more than in FIG. 3B.

[0041] In the following description, in the height direction H which is the stacking direction of the solar cell 100, the exposed surface of the protective layer 110 is referred to as "surface 111", and the surface of the protective layer 110 facing the surface 111 in the height direction H and in contact with the power generation element 101 is referred to as "bottom surface 112".

[0042] When light is irradiated toward the surface 111 of the solar cell 100 in which the protective layer 110 is not deteriorated, the incident light 2 is reflected at the surface 111 of the protective layer 110 and also transmitted through the protective layer 110 and reflected at the bottom surface 112. When the protective layer 110 is not deteriorated, as shown in FIG. 3A, a sufficient amount of the incident light 2 reaches the bottom surface 112, and most of the light reflected at the bottom surface 112 is output from the surface 111. As a result, not only the reflected light 3A reflected at the surface 111 of the protective layer 110 but also the reflected light 3B reflected at the bottom surface 112 of the protective layer 110 can be sufficiently detected. Therefore, as shown in FIG. 2A, in the solar cell 100 in which the protective layer is not deteriorated, the shape, pattern, etc. of the power generation element 101 are clearly shown.

[0043] On the one hand, as shown in FIG. 3B, when light is irradiated toward the surface 111 of the solar cell 100 with the protective layer 110 deteriorated, compared with the solar cell 100 without the deteriorated protective layer 110, the light 2 reaching the bottom surface 112 of the protective layer 110 decreases, and the reflected light 3B reflected at the bottom surface 112 of the protective layer 110 and output from the surface 111 decreases. As a result, the ratio of the reflected light 3B to the reflected light 3A decreases, and the shape, pattern, etc. of the power generation element 101 become less visible compared with the solar cell without the deteriorated protective layer.

[0044] Further, as shown in FIG. 3C, when light is irradiated toward the surface 111 of the solar cell 100 with the protective layer 110 further deteriorated, compared with the solar cell 100 without the deteriorated protective layer 110, the light 2 reaching the bottom surface 112 of the protective layer 110 further decreases, and the reflected light 3B reflected at the bottom surface 112 of the protective layer 110 and output from the surface 111 further decreases, and the ratio of the reflected light 3B to the reflected light 3A further decreases. As a result, the detected amount of the reflected light 3B further decreases, and as shown in FIG. 2B, the shape, pattern, etc. of the power generation element 101 become even less visible compared with the solar cell without the deteriorated protective layer.

[0045] As described above, in response to the deterioration of the protective layer 110 of the solar cell 100, the ratio of the reflected light 3B to the reflected light 3A in the solar cell 100 decreases. The inventor of the present application has found that the change in the ratio of the reflected light 3B to the reflected light 3A can be detected as a change in the apparent difference in the height H direction between the surface 111 and the bottom surface 112 of the protective layer 110 of the solar cell 100. Specifically, when the ratio of the reflected light 3B to the reflected light 3A in the solar cell 100 decreases, the apparent difference in the height H direction between the surface 111 and the bottom surface 112 of the protective layer 110 of the solar cell 100 becomes smaller than the actual difference in the height H direction between the surface 111 and the bottom surface 112 of the protective layer 110 of the solar cell 100. That is, as the deterioration of the protective layer 110 of the solar cell 100 progresses, the apparent difference in the height H direction between the surface 111 and the bottom surface 112 of the protective layer 110 of the solar cell 100 tends to become smaller. And the inventor of the present application has found that the difference in the height H direction between the surface 111 and the bottom surface 112 of the protective layer 110 having light transmissivity can be quantitatively measured by an index (parameter) indicating the surface roughness of an object.

[0046] Therefore, the sunlight deterioration evaluation apparatus 1 according to the present embodiment determines the degree of deterioration of the solar cell 100 by calculating an index indicating the surface roughness based on the reflected light 3 when the solar cell 100 is irradiated with light. Hereinafter, the configuration of the solar cell deterioration evaluation apparatus 1 will be described in detail.

[0047] As shown in FIG. 1, the sunlight deterioration evaluation apparatus 1 includes, for example, an irradiation unit 10, a slit member 20, a detection unit 30, a calculation unit 40, and a determination unit 60.

[0048] The irradiation unit 10 irradiates the solar cell 100 to be determined with the incident light 2. The irradiation unit 10 has, for example, a light source 11 and an irradiation lens unit 12. The light source 11 generates light. The light source 11 is, for example, a white LED. The light generated in the light source 11 is irradiated onto the solar cell 100 as the incident light 2 through the irradiation lens unit 12. The irradiation lens unit 12 is a mechanism for performing focus adjustment.

[0049] The slit member 20 is a component that transmits a part of the incident light. The slit member 20 is composed of, for example, a plate-like member 201, and a slit 202 is formed in the plate-like member 201. The plate-like member 201 is formed of, for example, a material that absorbs light.

[0050] At least one slit 202 is formed in the plate-like member 201. For example, a plurality of linear slits 202 are formed in the plate-like member 201 so as to be spaced apart from each other. In FIG. 1, a case where three linear slits 202 are formed in the plate-like member 201 so as to be spaced apart from each other is shown as an example.

[0051] The incident light 2 emitted from the irradiation unit 10 has its focus adjusted by the irradiation lens unit 12 and is irradiated onto the solar cell 100 as an object to be evaluated via the slit member 20. A slit image 21 is formed on the surface of the solar cell 100 by the incident light 2 irradiated onto the solar cell 100 after passing through the slit member 20. As shown in FIG. 1, when a plurality of linear slits 202 are formed in the slit member 20 so as to be spaced apart from each other, a slit image 21 in a stripe pattern in which a plurality of straight lines are arranged is formed on the solar cell 100.

[0052] The detection unit 30 detects the reflected light 3 reflected from the solar cell 100. The detection unit 30 has, for example, an imaging element 31 and a light receiving lens unit 32. The detection unit 30 detects, with the imaging element 31, the reflected light 3 generated when the incident light 2 irradiated from the irradiation unit 10 is reflected by the solar cell 100 via the light receiving lens unit 32. The light receiving lens unit 32 is a mechanism for performing focus adjustment. For example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor is adopted for the imaging element 31.

[0053] Further, when the incident light 2 irradiates the solar cell 100 after passing through the slit member 20, the detection unit 30 performs focus adjustment on the reflected light 3 affected by the shape of the slit image 21 formed by the incident light 2 passing through the slit member 20 with the light receiving lens unit 32, and then detects it with the imaging device 31.

[0054] The calculation unit 40 calculates an index 50 indicating the surface roughness of the solar cell 100 based on the reflected light 3 reflected from the solar cell 100 detected by the detection unit 30. Specifically, the calculation unit 40 calculates an index 50 indicating the surface roughness of the solar cell 100 based on the imaging information of the solar cell 100 formed by the reflected light 3 detected by the imaging device 31.

[0055] More specifically, when the incident light 2 irradiates the solar cell 100 after passing through the slit member 20, the calculation unit 40 calculates an index 50 indicating the surface roughness of the solar cell 100 based on the reflected light 3 affected by the shape of the slit image 21 detected by the detection unit 30. For example, the calculation unit 40 detects changes (strains) in the thickness and shape of the slit image 21 based on the reflected light 3 by an arithmetic method based on a non-contact roughness measurement technique using a known pattern light projection method, and calculates an index 50 indicating the surface roughness based on the strain.

[0056] The index 50 indicating the surface roughness includes, for example, at least one of the maximum height Sz, the arithmetic mean height Sa, the arithmetic mean curvature Spc of the peak points, the developed area ratio Sdr of the interface, and the aspect ratio Str of the surface properties. These are, for example, indices (parameters) defined by the ISO standard (ISO25178).

[0057] The determination unit 60 determines the degree of degradation of the solar cell 100 based on the index 50 indicating the surface roughness calculated by the calculation unit 40. The calculation unit 40 and the determination unit 60 are realized by a program processing device such as a microcontroller, for example. For example, in a program processing device including a processor and a memory, the calculation unit 40 and the determination unit 60 are realized when the processor executes various operations according to a program stored in the memory. Note that part or all of the calculation unit 40 and the determination unit 60 may be realized by a dedicated hardware circuit.

[0058] Specifically, the determination unit 60 determines the degree of degradation of the solar cell 100 based on the correspondence relationship information associating the index indicating the surface roughness with the degree of degradation of the solar cell 100, and the index 50 indicating the surface roughness calculated by the calculation unit 40.

[0059] Here, the correspondence relationship information may be, for example, a reference value (threshold value) serving as a criterion for determining the presence or absence of degradation of the solar cell 100, or may be a table associating the range of the index indicating the surface roughness with the stage (level) of the degree of degradation of the solar cell 100. For example, when determining the degree of degradation of the solar cell 100 in three stages of high degradation degree, medium degradation degree, and low degradation degree, a table associating each degradation degree with the range of the index indicating the surface roughness for each degradation degree may be used as the correspondence relationship information. Note that the correspondence relationship information may be stored in advance in the memory of the above-described program processing device.

[0060] Next, the flow of the process for determining the degree of degradation of the solar cell 100 by the solar light degradation evaluation device 1 will be described.

[0061] FIGS. 4A and 4B are flowcharts showing the flow of the process for determining the degree of degradation of the solar cell 100 by the solar light degradation evaluation device 1.

[0062] As specific determination methods of the determination unit 60, when adopting the maximum height, arithmetic mean height, arithmetic mean curvature of peak points, and developed area ratio of the interface as the index 50 indicating surface roughness, and when adopting the aspect ratio of the surface property as the index 50 indicating surface roughness, since the determination criteria are different, each determination method will be described below.

[0063] As a specific determination method of the determination unit 60, when adopting the maximum height, arithmetic mean height, arithmetic mean curvature of peak points, and developed area ratio of the interface as the index 50 indicating surface roughness, the determination of the degradation state of the solar cell is performed according to the flowchart shown in FIG. 4A. The content of each step in FIG. 4A is as follows.

[0064] First, the incident light 2 is irradiated from the light source 11 of the irradiation unit 10 toward the protective layer 110 of the solar cell 100 (step S1). Next, the detection unit 30 detects the reflected light 3 reflected from the protective layer 110 (step S2). Next, the calculation unit 40 calculates the index 50 indicating the surface roughness of the solar cell 100 based on the reflected light 3 reflected from the solar cell 100 detected by the detection unit 30 (step S3).

[0065] Next, the determination unit 60 determines whether the index 50 indicating the surface roughness calculated in step S3 is greater than or equal to the reference amount of the index indicating the surface roughness (step S4A). If the value is greater than or equal to the reference amount of the index indicating the surface roughness (step S4A: Yes), the determination unit 60 determines that the solar cell 100 is in a normal state (no degradation) (step S5). On the other hand, if the index 50 indicating the surface roughness shows a value less than the reference amount of the index indicating the surface roughness (step S4A: No), the determination unit 60 determines that the solar cell is in an abnormal state (with degradation) (step S6).

[0066] As a specific determination method of the determination unit 60, when adopting the aspect ratio of the surface property as the index 50 indicating surface roughness, the determination of the degradation state of the solar cell is performed according to the flowchart shown in FIG. 4B. The content of each step in FIG. 4B is as follows.

[0067] First, incident light 2 is irradiated from the light source 11 of the irradiation unit 10 toward the protective layer 110 of the solar cell 100 (step S1). Next, the detection unit 30 detects the reflected light 3 reflected from the protective layer 110 (step S2). Next, the calculation unit 40 calculates an index 50 indicating the surface roughness of the solar cell 100 based on the reflected light 3 detected by the detection unit 30 and reflected from the solar cell 100 (step S3).

[0068] Next, it is determined whether or not the index 50 indicating the surface roughness calculated in step S3 is less than the reference amount of the index indicating the surface roughness (step S4B). When the index 50 indicating the surface roughness shows a value less than the reference amount of the index indicating the surface roughness (step S4B: Yes), the determination unit 60 determines that the solar cell is in a normal state (without deterioration) (step S5). On the other hand, when the index 50 indicating the surface roughness shows a value equal to or greater than the reference amount of the index indicating the surface roughness (step S4B: No), the determination unit 60 determines that the solar cell is in an abnormal state (with deterioration) (step S6).

[0069] FIG. 5 is a diagram showing an example of the measurement results of the degree of deterioration of the solar cell 100 and the index 50 indicating the surface roughness.

[0070] In FIG. 5, as the index 50 indicating the surface roughness, the arithmetic mean height, the maximum height, the aspect ratio of the surface shape, the arithmetic mean curvature of the peak points, and the developed area ratio of the interface are adopted. FIG. 5 shows the experimental results when the solar cell 100 is irradiated with light using the solar cell deterioration evaluation apparatus 1 according to the present embodiment, and the index 50 indicating the surface roughness is calculated based on the reflected light 3 from the solar cell 100.

[0071] Experimental example A0 is the calculation result of the index 50 indicating the surface roughness when the reflected light 3 from the new solar cell 100 is detected by the solar cell deterioration evaluation apparatus 1. Experimental Example A1 shows the calculation result of the index 50 indicating the surface roughness when the reflected light 3 from the solar cell 100 is detected by the solar cell degradation evaluation device 1 after irradiating the solar cell 100 with light having a wavelength of about 290 nm to 340 nm for A1 hours as an accelerated degradation test in advance. Experimental Example A2 shows the calculation result of the index 50 indicating the surface roughness when the reflected light 3 from the solar cell 100 is detected by the solar cell degradation evaluation device 1 after irradiating the solar cell 100 with light having a wavelength of about 290 nm to 340 nm for A2 hours as an accelerated degradation test in advance. Experimental Example A3 shows the calculation result of the index 50 indicating the surface roughness when the reflected light 3 from the solar cell 100 is detected by the solar cell degradation evaluation device 1 after irradiating the solar cell 100 with light having a wavelength of about 290 nm to 340 nm for A3 hours as an accelerated degradation test in advance. Note that A1 hours < A2 hours < A3 hours.

[0072] As shown in Experimental Examples A0 to A3, it was found that the arithmetic mean height Sa, the maximum height Sz, the arithmetic mean curvature Spc of the peak points, and the developed area ratio Sdr of the interface become smaller as the time for irradiating the solar cell 100 with light having a wavelength of about 290 nm to 340 nm in advance is longer. That is, as the degradation of the solar cell 100 progresses, the respective values of the arithmetic mean height Sa, the maximum height Sz, the arithmetic mean curvature Spc of the peak points, and the developed area ratio Sdr of the interface become smaller.

[0073] Also, as shown in Experimental Examples A0 to A3, it was found that the aspect ratio Str of the surface properties becomes larger as the time for irradiating the solar cell 100 with light having a wavelength of about 290 nm to 340 nm in advance is longer. That is, as the degradation of the solar cell 100 progresses, the value of the aspect ratio Str of the surface properties becomes larger.

[0074] From these experimental examples, as described above, it is understood that the degree of degradation of the solar cell can be evaluated by the determination unit 60 comparing the index 50 indicating the surface roughness calculated by the calculation unit 40 with the reference amount of the index indicating the surface roughness set in advance.

[0075] Next, a method will be described in which the calculation unit 40 detects changes (strains) in the thickness and shape of the slit image 21 based on the reflected light 3 by an arithmetic method based on a non-contact roughness measurement technique using a known pattern light projection method, and calculates an index 50 indicating the surface roughness based on the strain.

[0076] FIG. 6A is a diagram showing a protective layer of a solar cell and a slit image used in an apparatus for evaluating the degree of degradation of a solar cell according to an embodiment of the present invention. FIG. 6B is a diagram showing the strain of the reflected light in an apparatus for evaluating the degree of degradation of a solar cell according to an embodiment of the present invention.

[0077] A plurality of vertical lines forming a striped pattern on the left side of FIG. 6A indicate the slit image 21. The rectangle on the right side of FIG. 6A indicates the protective layer 110. The slit image 21 is formed by the incident light 2 irradiated from the irradiation unit 10 through the slit member 20 onto the protective layer 110. As shown in FIG. 6B, the shape of this slit image 21 is different from the slit image 22 formed by the incident light 2 irradiated on the region other than the protective layer 110, and is affected by the refractive index of the protective layer 110. Therefore, compared with the slit image 22, a displacement occurs in the horizontal direction X.

[0078] However, as the degradation of the protective layer 110 progresses, the transmittance of the protective layer 110 decreases, so the detected amount of the reflected light 3 generated by the incident light 2 irradiated on the protective layer 110 decreases. As the detected amount of the reflected light 3 in the detection unit 30 decreases, the displacement difference, that is, the strain amount, in the horizontal direction X of the shape of the slit image 21 compared with the slit image 22 decreases. Thus, as the degradation of the protective layer 110 of the solar cell 100 progresses, the strain amount of the slit image 21 formed on the solar cell 100 changes. Therefore, as described above, the calculation unit 40 detects changes (strains) in the thickness and shape of the slit image 21 based on the reflected light 3, and calculates an index 50 indicating the surface roughness based on the strain, whereby it becomes possible to determine the degree of degradation of the solar cell 100.

[0079] Note that, as an index 50 indicating the surface roughness of the solar cell 100, the amount of strain itself of the slit image 21 may be adopted. For example, the displacement difference in the horizontal direction X between the reference slit image 22 and the slit image 21 is taken as the amount of strain. The calculation unit 40 calculates the amount of strain based on the reflected light 3 detected by the detection unit 30. The determination unit 60 compares the amount of strain calculated by the calculation unit 40 with a reference amount (threshold value) of the amount of strain of the slit image set in advance. When the calculated amount of strain is equal to or greater than the reference amount, the determination unit 60 determines that the solar cell is in a normal state (no degradation), and when the calculated amount of strain is less than the reference amount, the determination unit 60 determines that the solar cell is in a degraded state (with degradation).

[0080] As described above, the solar cell degradation evaluation device 1 according to the embodiment is a device 1 for evaluating the degree of degradation of a solar cell 100 having a power generation element 101 that generates electric power in response to the irradiated light 2 and a protective layer 110 laminated on the power generation element 101 to protect the power generation element 101. The device 1 includes an irradiation unit 10 that irradiates the light 2 from the light source 11, a detection unit 30 that detects the light 3 reflected from the solar cell 100, a calculation unit 40 that calculates an index 50 indicating the surface roughness of the solar cell 100 based on the light 3 reflected from the solar cell 100 detected by the detection unit 30, and a determination unit 60 that determines the degree of degradation of the solar cell 100 based on the index 50 indicating the surface roughness calculated by the calculation unit 40.

[0081] According to this, when the light 2 irradiated from the light source 11 of the solar cell degradation evaluation device 1 enters the protective layer 110 of the solar cell 100, the reflected light 3A reflected on the surface 111 of the protective layer 110 and the reflected light 3B reflected on the bottom surface 112 of the protective layer 110 are generated. However, as described above, according to the degree of degradation of the protective layer 110, the ratio of the reflected light 3B to the reflected light 3A changes. The detection unit 30 detects imaging information including the change in the ratio of the reflected light 3A and the reflected light 3B. The calculation unit 40 calculates an index 50 indicating the surface roughness of the solar cell 100 based on the imaging information detected by the detection unit 30. The determination unit 60 determines the degree of degradation of the solar cell 100 based on the index 50 indicating the surface roughness calculated by the calculation unit 40. Due to the operation of the above-described solar cell degradation evaluation device 1, in order to evaluate the degree of degradation of the solar cell 100, it is unnecessary to irradiate the protective layer 110 with light 2 and detect the light 2 transmitted through the protective layer 110 on the opposite side of the irradiation surface 111 of the protective layer 110, or to cut out the protective layer 110 from the solar cell 100. That is, the degree of degradation of the solar cell 100 can be evaluated nondestructively.

[0082] Further, the solar cell degradation evaluation device 1 according to the present embodiment uses the maximum height as the index 50 indicating the surface roughness.

[0083] According to this, by using an objective index, the degree of degradation of the solar cell 100 can be evaluated more accurately.

[0084] Further, the solar cell degradation evaluation device 1 according to the present embodiment uses the arithmetic mean height as the index 50 indicating the surface roughness.

[0085] According to this, by using an objective index, the degree of degradation of the solar cell 100 can be evaluated more accurately.

[0086] Further, the solar cell degradation evaluation device 1 according to the present embodiment uses the arithmetic mean curvature of the peak points as the index 50 indicating the surface roughness.

[0087] According to this, by using an objective index, the degree of deterioration of the solar cell 100 can be evaluated more accurately.

[0088] In addition, the solar cell deterioration evaluation device 1 according to the present embodiment uses the developed area ratio of the interface as an index 50 indicating the surface roughness.

[0089] According to this, by using an objective index, the degree of deterioration of the solar cell 100 can be evaluated more accurately.

[0090] In addition, the determination unit 60 of the solar cell deterioration evaluation device 1 according to the present embodiment determines that the degree of deterioration is higher as the index 50 indicating the surface roughness is smaller.

[0091] According to this, as any one of the maximum height, the arithmetic mean height, the arithmetic mean curvature of the peak points, or the developed area ratio of the interface, which is the index 50 indicating the surface roughness, becomes smaller, due to the deterioration of the protective layer 110, there is a correlation that the ratio of the reflected light 3B to the reflected light 3A decreases. Therefore, based on this relationship, the degree of deterioration of the solar cell 100 can be evaluated step by step.

[0092] In addition, the solar cell deterioration evaluation device 1 according to the present embodiment uses the aspect ratio of the surface properties as the index 50 indicating the surface roughness.

[0093] According to this, by using an objective index, the degree of deterioration of the solar cell 100 can be evaluated more accurately.

[0094] In addition, the determination unit 60 of the solar cell deterioration evaluation device 1 according to the present embodiment determines that the degree of deterioration is higher as the index 50 indicating the surface roughness is larger.

[0095] According to this, as the aspect ratio of the surface properties, which is the index 50 indicating the surface roughness, becomes larger, due to the deterioration of the protective layer 110, there is a correlation that the ratio of the reflected light 3B to the reflected light 3A decreases. Therefore, based on this relationship, the degree of deterioration of the solar cell 100 can be evaluated step by step.

[0096] Further, the solar cell degradation evaluation apparatus 1 according to the present embodiment irradiates light 2 toward the solar cell 100 through the slit member 20.

[0097] According to this, based on a known calculation method based on the pattern light projection method, it becomes possible to calculate with high accuracy an index 50 indicating the surface roughness based on the distortion of the slit image generated in the solar cell 100.

[0098] The solar cell degradation evaluation apparatus 1 according to the embodiment is an apparatus 1 for evaluating the degree of degradation of a solar cell 100 having a power generation element 101 that generates electric power in response to the light 2 irradiated as described above, and a protective layer 110 laminated on the power generation element 101 to protect the power generation element 101. The apparatus 1 includes an irradiation unit 10 that irradiates light 2 from a light source 11, a slit member 20 having a slit 202 in a stripe pattern shape that blocks a part of the light 2 irradiated from the irradiation unit 10 and passes a part of the light 2, a detection unit 30 that detects the light 3 reflected from the solar cell 100, a calculation unit 40 that calculates the distortion of the slit image 21 formed based on the light 3 reflected from the solar cell 100 detected by the detection unit 30, and a determination unit 60 that determines the degree of degradation of the solar cell 100 based on the distortion of the slit image 21 calculated by the calculation unit 40.

[0099] According to this, as the index 50 indicating the surface roughness, it is possible to adopt the amount of distortion that is the displacement difference in the horizontal direction X between the reference slit image 22 and the slit image 21, and it becomes possible to evaluate the degree of degradation of the solar cell by a simpler calculation.

[0100] ≪Expansion of the Embodiment≫ As described above, the invention made by the present inventors has been specifically described based on the embodiment. However, needless to say, the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof.

[0101] In the solar cell degradation evaluation device 1 according to the above embodiment, as the shape of the slit 202, a plurality of linear slits 202 that are spaced apart from each other and form a striped pattern are adopted. However, the present invention is not limited to this. For example, a plurality of concentric circular slits with different radii may be adopted.

[0102] Further, in the above embodiment, the case where the light 2 is irradiated onto the solar cell 100 through the slit member 20 is exemplified. However, if the index 50 indicating the surface roughness can be measured, the solar cell degradation evaluation device 1 may irradiate the light 2 onto the solar cell 100 without passing through the slit member 20, and measure the index 50 indicating the surface roughness based on the reflected light 3. In this case, the solar cell degradation evaluation device 1 may not have the slit member 20.

[0103] Further, in the above embodiment, the case where the index 50 indicating the surface roughness is calculated using the pattern light projection method as the measurement method of the index 50 indicating the surface roughness is exemplified. However, the present invention is not limited to this. For example, the solar cell degradation evaluation device 1 irradiates the laser light 2 onto the solar cell 100, and detects the reflected light 3 of the laser light 2 from the solar cell 100 to measure the index 50 indicating the surface roughness. A method capable of measuring the index 50 indicating the surface roughness of the object to be evaluated non - contact, such as a so - called laser probe method, may be adopted. That is, as long as the light 2 can be irradiated onto the solar cell 100 and the reflected light 3 from the solar cell 100 can be detected to measure the index 50 indicating the surface roughness, other methods may be adopted for the solar cell degradation evaluation device 1.

Explanation of Reference Numerals

[0104] 1 Solar cell degradation evaluation device 2 Incident light 3 Reflected light 10 Irradiation unit 11 Light source 12 Irradiation lens unit 20 Slit member 201 Plate - like member 202 Slit 21, 22 Slit image 30 Detection unit 31 Image sensor 32 Light - receiving lens unit 40 Calculation unit 50 Index indicating the surface roughness of the solar cell 60 Judgment unit 100 Solar cell 101 Power generation element 110 Protective layer 111 Surface part of the protective layer 112 Bottom part of the protective layer

Claims

1. A method for evaluating the degree of degradation of a solar cell having a power generation element that generates power in response to irradiated light and a protective layer laminated on the power generation element to protect the power generation element, a first step of irradiating the solar cell with light from a light source; a second step of detecting the light reflected from the solar cell; a third step of calculating an index indicating the surface roughness of the solar cell based on the detected light reflected from the solar cell; a fourth step of determining the degree of degradation of the solar cell based on the calculated index indicating the surface roughness, and including A method for evaluating the degree of degradation of a solar cell.

2. A method for evaluating the degree of degradation of a solar cell according to claim 1, wherein the index indicating the surface roughness includes the maximum height. A method for evaluating the degree of degradation of a solar cell.

3. A method for evaluating the degree of degradation of a solar cell according to claim 1, wherein the index indicating the surface roughness includes the arithmetic mean height. A method for evaluating the degree of degradation of a solar cell.

4. A method for evaluating the degree of degradation of a solar cell according to claim 1, wherein the index indicating the surface roughness includes the arithmetic mean curvature of the peak points. A method for evaluating the degree of degradation of a solar cell.

5. A method for evaluating the degree of degradation of a solar cell according to claim 1, wherein the index indicating the surface roughness includes the developed area ratio of the interface. A method for evaluating the degree of degradation of a solar cell.

6. A method for evaluating the degree of degradation of a solar cell according to any one of claims 1 to 5, wherein the fourth step includes a step of determining that the degree of degradation is higher as the index indicating the surface roughness is smaller. A method for evaluating the degree of degradation of a solar cell.

7. A method for evaluating the degree of degradation of a solar cell according to claim 1, wherein the index indicating the surface roughness includes the aspect ratio of the surface properties. A method for evaluating the degree of degradation of a solar cell.

8. A method for evaluating the degree of degradation of a solar cell according to claim 1 or 7, wherein the fourth step includes a step of determining that the degree of degradation is higher as the index indicating the surface roughness is larger. A method for evaluating the degree of degradation of a solar cell.

9. A method for evaluating the degree of degradation of a solar cell according to claim 1, The first step includes irradiating light toward the solar cell through a slit member having slits in the shape of a stripe pattern. A method for evaluating the degree of deterioration of a solar cell.

10. A method for evaluating the degree of deterioration of a solar cell having a power generation element that generates electric power in response to irradiated light and a protective layer laminated on the power generation element to protect the power generation element, a first step of irradiating light from a light source toward the solar cell via a slit member having slits in the shape of a stripe pattern; a second step of detecting the light reflected from the solar cell; a third step of calculating the distortion of a slit image formed based on the detected light reflected from the solar cell; and a fourth step of determining the degree of deterioration of the solar cell based on the calculated distortion. A method for evaluating the degree of deterioration of a solar cell.

11. An apparatus for evaluating the degree of deterioration of a solar cell having a power generation element that generates electric power in response to irradiated light and a protective layer laminated on the power generation element to protect the power generation element, an irradiation unit that irradiates light from a light source; a detection unit that detects the light reflected from the solar cell; a calculation unit that calculates an index indicating the surface roughness of the solar cell based on the light reflected from the solar cell detected by the detection unit; and a determination unit that determines the degree of deterioration of the solar cell based on the index indicating the surface roughness calculated by the calculation unit. characterized by comprising an apparatus for evaluating the degree of deterioration of a solar cell.

12. An apparatus for evaluating the degree of deterioration of a solar cell according to claim 11, wherein the index indicating the surface roughness includes the maximum height. An apparatus for evaluating the degree of deterioration of a solar cell.

13. An apparatus for evaluating the degree of deterioration of a solar cell according to claim 11, wherein the index indicating the surface roughness includes the arithmetic mean height. An apparatus for evaluating the degree of deterioration of a solar cell.

14. An apparatus for evaluating the degree of deterioration of a solar cell according to claim 11, wherein the index indicating the surface roughness includes the arithmetic mean curvature of the peak points. An apparatus for evaluating the degree of deterioration of a solar cell.

15. An apparatus for evaluating the degree of deterioration of a solar cell according to claim 11, wherein the index indicating the surface roughness includes the developed area ratio of the interface. An apparatus for evaluating the degree of deterioration of a solar cell.

16. An apparatus for evaluating the degree of degradation of a solar cell according to any one of claims 11 to 15, wherein the determination unit determines that the higher the degree of degradation, the smaller the index indicating the surface roughness. An apparatus for evaluating the degree of degradation of a solar cell.

17. An apparatus for evaluating the degree of degradation of a solar cell according to claim 11, wherein the index indicating the surface roughness includes the aspect ratio of the surface property. An apparatus for evaluating the degree of degradation of a solar cell.

18. An apparatus for evaluating the degree of degradation of a solar cell according to claim 11 or 17, wherein the determination unit determines that the higher the degree of degradation, the larger the index indicating the surface roughness. An apparatus for evaluating the degree of degradation of a solar cell.

19. An apparatus for evaluating the degree of degradation of a solar cell according to claim 11, further comprising a slit member having a stripe-shaped slit that blocks a part of the light irradiated from the irradiation unit and allows a part of the light to pass through, wherein the solar cell is irradiated with light through the slit member. An apparatus for evaluating the degree of degradation of a solar cell.

20. An apparatus for evaluating the degree of degradation of a solar cell having a power generation element that generates electric power in response to irradiated light and a protective layer laminated on the power generation element to protect the power generation element, comprising an irradiation unit that irradiates light from a light source, a slit member having a stripe-shaped slit that blocks a part of the light irradiated from the irradiation unit and allows a part of the light to pass through, a detection unit that detects the light reflected from the solar cell, a calculation unit that calculates the distortion of the slit image formed based on the light reflected from the solar cell detected by the detection unit, and a determination unit that determines the degree of degradation of the solar cell based on the distortion of the slit image calculated by the calculation unit. Characterized by comprising An apparatus for evaluating the degree of degradation of a solar cell.

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