Photovoltaic cell hidden crack detector

Abstract

The present application relates to the field of photovoltaic detection equipment, and discloses a photovoltaic cell hidden crack detector, comprising an adjustable step-down power supply, an adjustable pulse high-voltage power supply and a defect positioning film; the defect positioning film comprises a flexible substrate, one side of the flexible substrate is sprayed with a thermochromic coating layer, and the other side is sprayed with a mixed fluorescent coating layer containing at least two different wavelength fluorescent powders; a conductive coating is sprayed on the side of the mixed fluorescent coating layer away from the flexible substrate; the power input end of the adjustable step-down power supply and the adjustable pulse high-voltage power supply are connected in parallel to an AC power supply; the power output end of the adjustable step-down power supply is connected to the positive and negative output ends of the photovoltaic panel under test, one end of the signal output end of the adjustable pulse high-voltage power supply is connected to the defect positioning film and the ground end, and the other end is connected to a power output end of the adjustable step-down power supply, and the defect positioning film is grounded to the outer frame of the photovoltaic panel under test; the present application can realize the detection of hidden cracks in operating photovoltaic power generation.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic detection equipment, and in particular to a photovoltaic cell hidden crack detector. Background Art

[0002] Photovoltaic cell modules often have surface cracks due to improper transportation and installation. Hidden cracks can cause oxidation and deterioration of the internal wafers of the photovoltaic panels, resulting in hot spots and breakdown, leading to a decrease in power generation capacity. Since multiple modules need to be operated in series, the deterioration of the characteristics of a single module will have a great impact on the power generation of the entire string. However, existing technologies cannot detect whether there are hidden cracks in the photovoltaic panels in operation, and where the hidden cracks are. Therefore, in the operation of a large number of photovoltaic power stations, the overall power generation has suffered a great loss due to the presence of some hidden cracks in the photovoltaic panels. It is extremely necessary to develop equipment that can detect hidden cracks in photovoltaic modules, which can bring great benefits to the application and promotion of photovoltaic power generation. Summary of the invention

[0003] In order to facilitate the detection of hidden cracks in operating photovoltaic power generation, the present application provides a photovoltaic cell hidden crack detector.

[0004] The present application provides a photovoltaic cell hidden crack detector, which adopts the following technical solution:

[0005] A photovoltaic cell hidden crack detector, comprising an adjustable step-down power supply, an adjustable pulse high-voltage power supply and a defect positioning film;

[0006] The defect location film comprises a flexible substrate, one side of the flexible substrate is sprayed with a thermochromic coating layer, the other side of the flexible substrate is sprayed with a mixed fluorescent coating layer containing at least two fluorescent powders of different wavelengths, and the side of the mixed fluorescent coating layer away from the flexible substrate is also sprayed with a conductive coating; the defect location film is evenly attached to the light-receiving surface of the photovoltaic panel to be tested on one side of the conductive coating;

[0007] After the adjustable step-down power supply is connected in parallel with the two AC power input terminals of the adjustable pulse high-voltage power supply, the two AC power input terminals are connected to the AC power supply; the two power output terminals of the adjustable step-down power supply are connected to the positive and negative output terminals of the photovoltaic panel under test; one signal output terminal of the adjustable pulse high-voltage power supply is connected to the defect location film and the ground terminal, and the other signal output terminal is connected to one of the power output terminals of the adjustable step-down power supply, and the defect location film is connected to the outer frame of the photovoltaic panel under test and the ground terminal;

[0008] The two power output ends of the adjustable step-down power supply input a current not greater than a set threshold to the positive and negative electrodes of the photovoltaic panel under test; after the hot spot damage area on the defect positioning film appears, the adjustable pulse high-voltage power supply inputs a high-voltage pulse signal to the positive or negative electrode of the photovoltaic panel under test.

[0009] By adopting the above technical solution, the present invention applies a large current between the positive and negative electrodes of the photovoltaic panel through an adjustable step-down power supply, thereby realizing different surface heating through different current densities in the resistance-enhanced area, and combining with the defect positioning film, the hot spot damage area can be intuitively found through the color change distribution of the thermochromic coating layer on the film. Further adopting a high-voltage pulse power supply, since the surface hidden cracks are extremely fine and cannot be found by general optical methods, a high-voltage pulse is applied by a high-voltage pulse power supply, and combined with the coating of the metal conductive part of the defect positioning film, a high-voltage discharge will occur at the weak insulation of the hidden cracks. The infrared signal generated by the discharge is converted into a visible light through the fluorescent coating of the first wavelength, and the ultraviolet light generated by the discharge is converted into another visible light through the fluorescent coating of the second wavelength. By observing the luminescence of the defect positioning film, it is possible to intuitively find whether there are hidden cracks and the location of the hidden cracks.

[0010] Optionally, electrostatic flocking is performed after the spraying process of the mixed fluorescent paint layer and the metal powder layer is completed.

[0011] By adopting the above technical solution, electrostatic flocking is performed after the two coating spraying processes are completed to increase the adhesion and wear resistance of the defect positioning film.

[0012] Optionally, the two phosphors with different wavelengths include conversion phosphor and green rare earth phosphor.

[0013] By adopting the above technical solution, high-voltage pulses are applied through a high-voltage pulse power supply, combined with the coating of the metal conductive part of the defect positioning film, high-voltage discharge will occur at the weak insulation of the hidden cracks, and the infrared signal generated by the discharge is converted into visible light through the up-conversion fluorescent coating, and the ultraviolet light generated by the discharge is converted into green visible light through the green rare earth phosphor coating. By observing the luminescence of the defect positioning film, it is possible to intuitively find whether there are hidden cracks and the location of the hidden cracks.

[0014] Optionally, the conductive coating comprises a metal powder layer, and the metal powder particles of the metal powder layer are not larger than 1000 mesh.

[0015] By adopting the above technical solution, the metal powder particles are no larger than 1000 mesh, the surface area is increased, and the contact between particles is closer, thereby improving the conductivity and mechanical properties of the conductive coating. In addition, the fine particles can also fill the tiny depressions on the surface of the flexible substrate, making the conductive coating flatter and smoother.

[0016] Optionally, the adjustable step-down power supply is an adjustable AC power supply with a voltage range of 0-120V and a current of not less than 50A, and the adjustable pulse high-voltage power supply is a high-voltage AC pulse power supply with a voltage range of 0-10KV.

[0017] By adopting the above technical solution, the voltage range of 0-120V can cover the testing requirements of most photovoltaic cells, ensuring that no excessive voltage shock is caused to the photovoltaic cells during the test; the current setting of not less than 50A ensures that sufficient current can be provided during the test to stimulate the electroluminescence phenomenon inside the photovoltaic cell, thereby clearly showing defects such as hidden cracks.

[0018] Optionally, the flexible substrate includes a polyethylene layer, a polypropylene layer, a polyester layer, a polyvinyl chloride layer, a polyimide layer or a polytetrafluoroethylene layer.

[0019] By adopting the above technical solution, the flexible substrate serves as the carrier of the detection film, carrying key components such as the conductive coating, the mixed fluorescent coating layer and the thermochromic coating layer. The flexibility and weather resistance of the flexible substrate ensure that the detection film can fit tightly on the surface of the photovoltaic panel and resist erosion from harsh environmental conditions. In addition, the processability of the flexible substrate allows the detection film to be customized according to the actual needs of the photovoltaic panel, improving the accuracy and efficiency of the detection.

[0020] Optionally, it also includes a camera, which is electrically connected to a controller; the camera is used to capture a detection image of the defect positioning film; the controller calculates the area of ​​the hot spot damage area based on the detection image; the controller adjusts the voltage value of the adjustable pulse high-voltage power supply according to the size of the area; the larger the area, the smaller the voltage value; the smaller the area, the larger the voltage value.

[0021] By adopting the above technical solution, when the area of ​​the hot spot damage area increases, the controller will automatically reduce the voltage value of the adjustable step-down power supply; conversely, when the area of ​​the hot spot damage area decreases, the controller will automatically increase the voltage value of the adjustable step-down power supply. The automated processing and analysis process reduces manual intervention and errors, and improves detection efficiency and quality.

[0022] Optionally, the controller is further included to calculate the growth rate of the hot spot damage area based on the monitoring image within a set time period; adjust the current value of the adjustable step-down power supply according to the growth rate, the greater the growth rate, the smaller the current value; the smaller the growth rate, the larger the current value.

[0023] By adopting the above technical solution, the faster the growth rate of the hot spot damage area, the faster the hot spot damage is spreading. At this time, the controller will reduce the current value to reduce the working current and temperature of the photovoltaic panel, thereby slowing down the spread of the hot spot damage; the slower the growth rate, the hot spot damage is relatively stable or slowing down. At this time, the controller will increase the current value to maintain the normal working state of the photovoltaic panel. The automated processing and analysis process reduces manual intervention and errors, and improves detection efficiency and quality.

[0024] Optionally, a transparent thin airbag layer is provided on a side of the thermochromic coating layer away from the flexible substrate; an airbag filled with an inert gas is provided in the transparent thin airbag layer.

[0025] By adopting the above technical solution, since the flexible substrate is flexible and the thermochromic coating layer is sprayed on, in order to protect the thermochromic coating layer, the transparent thin airbag layer can be applied to the thermochromic coating layer during use, reducing the possibility of the thermochromic coating layer falling off, and blocking the influence of the external temperature on the thermochromic coating, reducing the possibility of misjudgment. Therefore, the transparent thin airbag layer can fit tightly on the thermochromic coating layer to provide it with an additional protective layer. During use, even if it encounters external impacts such as friction and collision, the transparent thin airbag layer can absorb part of the impact force and reduce the risk of damage to the thermochromic coating layer. In addition, the airbag can play a magnifying role, which is more conducive to observing the location of hot spots or cracks.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: it can accurately detect hidden crack problems in photovoltaic modules and the locations where they occur, promptly discover problematic modules in a whole string of modules, and can detect hot spot areas and surface crack areas, providing strong assistance for future repairs and replacements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the circuit diagram of the first photovoltaic cell hidden crack detector in Example 1.

[0028] Figure 2 Schematic diagram of the layer structure of the defect positioning film in Example 1.

[0029] Figure 3 This is the circuit diagram of the second photovoltaic cell hidden crack detector in Example 1.

[0030] Figure 4 Schematic diagram of the layer structure of the defect positioning film in Example 2.

[0031] Figure numerals: 1. adjustable step-down power supply; 2. adjustable pulse high-voltage power supply; 3. signal output terminal; 4. power output terminal; 5. defect positioning film; 6. flexible substrate; 7. thermochromic coating layer; 8. mixed fluorescent coating layer; 9. metal powder layer; 10. transparent thin airbag layer. DETAILED DESCRIPTION

[0032] The present application is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] Example 1

[0034] The present application embodiment discloses a photovoltaic cell hidden crack detector, referring to Figure 1 and Figure 2 , including an adjustable step-down power supply 1, an adjustable pulse high-voltage power supply 2 and a defect positioning film 5.

[0035] The defect location film 5 includes a flexible substrate 6, and its outer dimensions are consistent with the length and width of the photovoltaic panel being tested. The side of the flexible substrate 6 away from the photovoltaic panel being tested is facing upward, and the side close to the photovoltaic panel being tested is facing downward. A thermochromic coating layer 7 is evenly sprayed on the upper surface. The thermochromic coating layer 7 can use a reversible temperature-changing coating. When the temperature rises, the color of the coating changes; when the temperature drops, the color returns to the previous state. A mixed fluorescent coating layer 8 containing at least two different wavelength fluorescent powders is evenly sprayed toward the lower side close to the flexible substrate 6. Among them, the mixed fluorescent coating layer 8 includes, for example, a mixed fluorescent coating layer 8 of conversion fluorescent powder and green rare earth fluorescent powder. A conductive coating is evenly sprayed toward the lower side close to the photovoltaic panel being tested.

[0036] Among them, the polyethylene layer, polypropylene layer, polyester layer, polyvinyl chloride layer, polyimide layer or polytetrafluoroethylene layer of the flexible substrate 6 of the defect positioning film 5 is a plastic material. The flexible substrate 6 uses plastic material as a carrier of the detection film, which not only has good chemical and physical properties, but also can carry key components such as conductive coating, mixed fluorescent coating layer 8 and thermochromic coating layer 7. The flexibility and weather resistance of the flexible substrate 6 ensure that the detection film can fit tightly on the surface of the photovoltaic panel and can resist erosion from harsh environmental conditions. In addition, from the perspective of processability, the processability of the flexible substrate 6 allows the detection film to be customized according to the actual needs of the photovoltaic panel, thereby improving the accuracy and efficiency of the detection.

[0037] Among them, the conductive coating is such as the metal powder layer 9, and the metal powder particles of the metal powder layer 9 are not larger than 1000 mesh. The metal powder particles not larger than 1000 mesh have a larger surface area and closer contact between particles, thereby improving the conductive performance and mechanical properties of the conductive coating. In addition, the fine particles can also fill the tiny depressions on the surface of the flexible substrate 6, making the conductive coating more flat and smooth.

[0038] Among them, electrostatic flocking is performed after the spraying process of the mixed fluorescent paint layer 8 and the metal powder layer 9 is completed, and electrostatic flocking is performed after the spraying process of the two paints is completed to increase the adhesion and wear resistance of the defect positioning film 5.

[0039] When in use, the defect location film 5 is evenly applied to the light-receiving surface of the photovoltaic panel being tested, and evenly and smoothly applied to the glass panel of the light-receiving surface of the photovoltaic panel. The size of the defect location film 5 is consistent with the length and width of the photovoltaic panel being tested.

[0040] Adjustable step-down power supply 1: It is an AC adjustable power supply with a voltage range of 0-120V and a current of not less than 50A, which is used to provide stable voltage and current for the photovoltaic panel under test. The voltage range of 0-120V can cover the test requirements of most photovoltaic cells, ensuring that there will be no excessive voltage shock to the photovoltaic cells during the test.

[0041] Adjustable pulse high voltage power supply 2: It is a high voltage AC pulse power supply of 0-10KV, which is used to generate high voltage pulses on the defect location film 5, stimulate the phosphor to emit light and detect potential defects. The current is set to not less than 50A, which ensures that sufficient current can be provided during the test to stimulate the electroluminescence phenomenon inside the photovoltaic cell, so as to clearly show defects such as hidden cracks.

[0042] Circuit connections for the test circuit:

[0043] Power input terminal: The power input terminals of the adjustable step-down power supply 1 and the adjustable pulse high-voltage power supply 2 are connected in parallel and connected to the AC mains power supply.

[0044] Power supply output terminal 4: The power supply output terminal 4 of the adjustable step-down power supply 1 is connected to the positive and negative output terminals of the photovoltaic panel under test, and is used to provide test voltage and current.

[0045] Reference Figure 1 and Figure 3 , signal output terminal 3: one end of the signal output terminal 3 of the adjustable pulse high-voltage power supply 2 is connected to the defect location film 5 and the ground terminal, and the other end is connected to a power output terminal 4 (positive or negative) of the adjustable step-down power supply 1 to form a complete test circuit. Among them, Figure 3 The signal output terminal 3 of the adjustable pulse high-voltage power supply 2 is connected to the negative pole of the photovoltaic panel under test which is connected to the adjustable step-down power supply 1 .

[0046] Ground connection: The defect location film 5 is connected to the outer frame of the photovoltaic panel being tested and the ground terminal as a whole to ensure safety during the test.

[0047] When high voltage discharge occurs, heat is generated in the discharge area. This is because during the discharge process, electrons collide with gas molecules or atoms in solid insulating materials, resulting in energy conversion and local heating. This local heating increases the temperature of the discharge area, thereby emitting infrared radiation.

[0048] High-voltage discharge also produces ultraviolet light. When the electric field strength in the insulating layer exceeds a certain threshold, it will cause gas ionization or local breakdown of solid insulating materials, resulting in discharge. During the discharge process, electrons collide with gas molecules or atoms in solid insulating materials, exciting electrons in atoms or molecules to jump to high energy levels. When these electrons fall back to low energy levels, they release energy, part of which is radiated in the form of ultraviolet light.

[0049] The conversion phosphor in the mixed fluorescent coating layer 8 is a material that can convert light of one wavelength into light of another wavelength. It is usually a compound composed of rare earth elements or other special elements, which can emit fluorescence after being excited. This phosphor has stable luminous performance, pure color, and high luminous efficiency.

[0050] The green rare earth phosphor in the mixed fluorescent coating layer 8 is a rare earth material that can emit green fluorescence. It also has stable luminous performance and high luminous efficiency. Green rare earth phosphor is widely used in the fields of lighting, display, etc., especially in LED lighting, where it can improve the color rendering index and color temperature stability of the light source.

[0051] Working principle of fluorescence: When the mixed fluorescent coating layer 8 is excited by an external light source (such as ultraviolet light, visible light, etc.), the conversion phosphor and the green rare earth phosphor absorb the excitation light and emit fluorescence. Since the emission wavelengths of the two phosphors are different, the fluorescence colors they emit will also be different. By adjusting the ratio of the two phosphors and the wavelength of the excitation light, the emission color of the mixed coating can be regulated.

[0052] The present invention can accurately detect the problem of hidden cracks in photovoltaic components and timely find the components with problems in a whole string of components. The present invention uses an adjustable step-down power supply 1 to apply a large current between the positive and negative electrodes of the photovoltaic panel, so as to achieve different surface heating through the difference in current density in the area where the resistance increases. Combined with the defect positioning film 5 of the present invention, the hot spot damage area can be intuitively found through the color change distribution of the thermochromic coating layer 7 on the defect positioning film 5. The present invention further adopts an adjustable pulse high-voltage power supply 2. Since the surface hidden cracks are extremely fine, they cannot be found by general optical methods. By applying high-voltage pulses through the high-voltage pulse power supply, combined with the metal conductive coating of the defect positioning film 5, high-voltage discharge will occur at the weak insulation of the hidden cracks. The infrared signal generated by the discharge is converted into visible light through the up-conversion fluorescent coating, and the ultraviolet generated by the discharge is converted into green visible light through the fluorescent coating. By observing the luminescence of the defect positioning film 5, it is possible to intuitively find whether there are hidden cracks and the location of the hidden cracks. In addition, the present invention has a very low cost. The mass production cost of a set of equipment is less than one thousand yuan, which provides a good new technology for on-site quality inspection of photovoltaic equipment.

[0053] Example 2

[0054] The structure of Example 2 of the present application is the same as that of Example 1, except that the control method is different:

[0055] In Example 2, in order to improve the efficiency of detection and optimize the control algorithm, a camera is also included, and the camera is electrically connected to the controller.

[0056] The camera takes a picture of the defect location film 5 as a detection image, and the controller uses an image processing algorithm to identify the hot spot damage area in the detection image and calculate the area of ​​the hot spot damage area. The image processing algorithm includes threshold segmentation, edge detection, etc.

[0057] The controller adjusts the voltage value of the adjustable pulse high-voltage power supply 2 according to the size of the area; the larger the area, the smaller the voltage value; the smaller the area, the larger the voltage value. The larger the area, the more serious the damage. The larger the area, the more serious the damage. The larger the area, the higher the energy accumulation and the more serious the temperature anomaly, which increases the risk of damage to the photovoltaic panel. By reducing the voltage value of the pulse, further damage to the photovoltaic panel can be reduced.

[0058] Examples of linear function relationships:

[0059] V = V_max - m × A;

[0060] in:

[0061] V represents the voltage value of the adjustable step-down power supply 1 (V);

[0062] V_max represents the maximum voltage value (for example, 24V);

[0063] m represents a coefficient used to control the influence of area on voltage value;

[0064] A represents the area of ​​the hot spot damage region (square centimeters);

[0065] The voltage value is automatically adjusted according to the actual area of ​​hot spot damage, thereby further protecting the photovoltaic panels and optimizing energy utilization. When the area of ​​the hot spot damage area increases, the controller automatically reduces the voltage value of the adjustable step-down power supply 1; conversely, when the area of ​​the hot spot damage area decreases, the controller automatically increases the voltage value of the adjustable step-down power supply 1.

[0066] In order to further optimize the control method, the controller also calculates the growth rate of the hot spot damage area based on the monitoring images within the set time period; adjusts the current value of the adjustable step-down power supply 1 according to the growth rate, the greater the growth rate, the smaller the current value; the smaller the growth rate, the greater the current value.

[0067] For example, an example of a linear function relationship:

[0068] I = I_max - k × v;

[0069] in:

[0070] I represents the current value of the adjustable step-down power supply 1 (A);

[0071] I_max represents the maximum current value (for example, 10A);

[0072] k represents a coefficient used to control the influence of the growth rate on the current value;

[0073] v represents the growth rate of the hot spot damage area (% / second);

[0074] The current value is automatically adjusted according to the actual situation of hot spot damage, thereby achieving effective protection of photovoltaic panels and optimizing energy utilization. The faster the growth rate of the hot spot damage area, the faster the hot spot damage is spreading. At this time, the controller will reduce the current value to reduce the working current and temperature of the photovoltaic panel, thereby slowing down the spread of hot spot damage; the slower the growth rate, the relatively stable or slowing hot spot damage. At this time, the controller will increase the current value to maintain the normal working state of the photovoltaic panel.

[0075] Example 3

[0076] The structure of Example 3 of the present application is basically the same as that of Example 1, except that a transparent thin airbag layer 10 is additionally provided in Example 3.

[0077] Reference Figure 4A transparent thin airbag layer 10 is arranged on the side of the thermochromic coating layer 7 away from the flexible substrate 6; airbags filled with inert gas are evenly arranged in the transparent thin airbag layer 10. The inert gas is, for example, helium, neon, argon, krypton, xenon, etc.

[0078] By introducing the transparent thin airbag layer 10 as a protective layer, the influence of the external temperature on the thermochromic coating layer 7 can be effectively reduced, the possibility of misjudgment can be reduced, and the accuracy of detection can be improved. The use of the transparent thin airbag layer 10 can reduce the direct contact and wear between the thermochromic coating layer 7 and the photovoltaic cell panel, extend the service life, and reduce maintenance costs. This technical solution can be applied to the needs of photovoltaic cell hidden crack detection in various complex environments and conditions, and improves the scope of application and practicality of the detector.

[0079] In practical applications, the transparent thin airbag layer 10 can be tightly combined with the thermochromic coating layer 7 and ensure that it is tightly attached to the flexible substrate 6. At the same time, the airbag needs to be inflated and ensure that it is filled with inert gas. During use, the detection film can be applied to the photovoltaic panel, and the color change on the transparent thin airbag layer 10 can be observed to determine whether the photovoltaic panel has hot spot damage and other problems. In addition, the detection film can be cut and adjusted according to actual needs to adapt to photovoltaic panels of different shapes and sizes.

[0080] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A photovoltaic cell hidden crack detector, characterized in that: It comprises an adjustable step-down power supply (1), an adjustable pulse high-voltage power supply (2) and a defect positioning film (5); The defect location film (5) comprises a flexible substrate (6), one side of the flexible substrate (6) is sprayed with a thermochromic coating layer (7), the other side of the flexible substrate (6) is sprayed with a mixed fluorescent coating layer (8) containing at least two fluorescent powders of different wavelengths, and the side of the mixed fluorescent coating layer (8) away from the flexible substrate (6) is also sprayed with a conductive coating; the defect location film (5) is provided with a side of the conductive coating and is evenly applied to the light-receiving surface of the photovoltaic panel to be tested; the two fluorescent powders of different wavelengths include conversion fluorescent powder and green rare earth fluorescent powder; After the adjustable step-down power supply (1) and the two AC power supply input terminals of the adjustable pulse high-voltage power supply (2) are connected in parallel, the two AC power supply input terminals are connected to the AC power supply; the two power supply output terminals (4) of the adjustable step-down power supply (1) are connected to the positive and negative output terminals of the photovoltaic panel under test; one signal output terminal (3) of the adjustable pulse high-voltage power supply (2) is connected to the defect location film (5) and the ground terminal, and the other signal output terminal (3) is connected to one of the power supply output terminals (4) of the adjustable step-down power supply (1); the defect location film (5) is connected to the outer frame of the photovoltaic panel under test and the ground terminal; Two power output terminals (4) of the adjustable step-down power supply (1) input a current not greater than a set threshold value to the positive and negative electrodes of the photovoltaic panel under test; After the hot spot damage area on the defect positioning film (5) appears, the adjustable pulse high-voltage power supply (2) inputs a high-voltage pulse signal to the positive electrode or the negative electrode of the photovoltaic panel being tested.

2. The photovoltaic cell hidden crack detector according to claim 1, characterized in that: The conductive coating comprises a metal powder layer (9), and the metal powder particles of the metal powder layer (9) are not larger than 1000 meshes.

3. The photovoltaic cell hidden crack detector according to claim 2, characterized in that: The mixed fluorescent paint layer (8) and the metal powder layer (9) are electrostatically flocked after the spraying process is completed.

4. The photovoltaic cell hidden crack detector according to claim 1, characterized in that: The adjustable step-down power supply (1) is an adjustable AC power supply with a voltage range of 0-120V and a current of not less than 50A, and the adjustable pulse high-voltage power supply (2) is a high-voltage AC pulse power supply with a voltage range of 0-10KV.

5. The photovoltaic cell hidden crack detector according to claim 1, characterized in that: The flexible substrate (6) comprises a polyethylene layer, a polypropylene layer, a polyester layer, a polyvinyl chloride layer, a polyimide layer or a polytetrafluoroethylene layer.

6. The photovoltaic cell hidden crack detector according to claim 1, characterized in that: It also includes a camera, which is electrically connected to a controller; the camera is used to capture a detection image of the defect positioning film (5); the controller calculates the area of ​​the hot spot damage region based on the detection image; and the controller adjusts the voltage value of the adjustable pulse high-voltage power supply (2) based on the size of the area; The larger the area, the smaller the voltage value; and the smaller the area, the larger the voltage value.

7. The photovoltaic cell hidden crack detector according to claim 6, characterized in that: It also includes a controller that calculates the growth rate of the hot spot damage area based on the monitoring images within a set time period; adjusts the current value of the adjustable step-down power supply (1) according to the growth rate, the greater the growth rate, the smaller the current value; the smaller the growth rate, the greater the current value.

8. The photovoltaic cell hidden crack detector according to claim 1, characterized in that: A transparent thin airbag layer (10) is arranged on the side of the thermochromic paint layer (7) away from the flexible substrate (6); an airbag filled with an inert gas is arranged in the transparent thin airbag layer (10).

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