A method for hot spot durability testing of a photovoltaic module
The photovoltaic module hot spot durability testing method, which uses short-circuit-assisted screening and precise cell selection, solves the problems of cumbersome testing methods and mismatch with operating conditions in the existing methods, and achieves more efficient and accurate hot spot temperature measurement and module performance evaluation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YINGLI ENERGY DEV CO LTD
- Filing Date
- 2026-04-16
- Publication Date
- 2026-07-14
AI Technical Summary
Existing methods for testing hot spots on photovoltaic modules are cumbersome and the test conditions do not match the actual usage conditions, resulting in distorted temperature data and easy damage to the modules.
Short-circuit assisted screening and testing were adopted, combined with precise cell selection, shielding optimization and temperature control. Target hot spot cells were selected by short-circuit scanning, the optimal shielding area was determined, and the hot spot was subjected to durable exposure in an irradiation environment. The temperature was recorded, the bypass diode function was verified, and finally the initial state was restored to compare the electrical performance.
It improved testing efficiency, made testing conditions closer to actual operating conditions, avoided component failure caused by excessively high hot spot temperature, and obtained real and effective hot spot temperature data.
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Figure CN122394499A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photovoltaic module testing technology, and in particular to a method for testing the durability of hot spots in photovoltaic modules. Background Technology
[0002] This invention relates to the field of photovoltaic module testing technology. Photovoltaic modules are the core components of photovoltaic power generation systems, used to convert solar energy into electrical energy, and their operational reliability directly affects the system stability. Photovoltaic modules are prone to hot spot effects due to localized shading or defects in the cells themselves. Long-term hot spot effects can lead to failures such as module burnout and solder joint melting, necessitating hot spot durability testing.
[0003] Existing photovoltaic module hot spot testing methods mainly target half-cell or 1 / 3-cell modules. Different proportions of shading are applied to each cell under test to determine the stringent shading conditions. The module is short-circuited throughout the process to collect hot spot temperatures and complete the test.
[0004] Existing methods involve cumbersome cell screening processes, mismatch between test conditions and actual usage conditions, and continuous short-circuiting that results in excessively high hot spot temperatures, which can easily lead to module failure after testing. Consequently, the temperature data has low reference value. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for testing the hot spot durability of photovoltaic modules. This method uses shorting as an auxiliary screening and testing tool, combined with precise cell selection, shading optimization, and temperature control. It solves the problems of cumbersome screening, poor operating condition matching, distorted temperature data, and easy damage to modules in existing methods, making the testing process simpler and the testing conditions closer to the actual operating state of the modules.
[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: A method for testing the hot spot durability of photovoltaic modules includes the following steps: Test the initial electrical performance data of photovoltaic modules; Short-circuit the output of the module, scan the module under irradiation conditions, and select the target hot spot cell and the control cell; Short-circuit the module and test the shading ratio of the selected cells under irradiation conditions to determine the optimal shading area; shade the selected cells according to the optimal shading area, short-circuit the module and place it in the irradiation environment for hot spot durability exposure, and record the temperature of the hot spot cells. Verify the bypass diode function of the component; After the hot spot durability test is completed, the module is restored to its initial state, and the electrical performance parameters of the module are tested and compared with the initial electrical performance data to evaluate the module performance.
[0007] Furthermore, the photovoltaic modules are pre-treated before testing to bring them to a thermally stable state; the pre-treatment includes placing the modules in an environment with set temperature and humidity for a preset time, and ensuring that the bypass diodes are wired correctly.
[0008] Furthermore, before selecting the target hot spot battery and the control battery, an initial defect check is performed on the components to exclude components with initial defects; the initial defect check includes scanning the surface of the components to record the initial temperature distribution and using electroluminescence to detect the internal state of the battery cells.
[0009] Furthermore, when selecting target hot spot cells and control cells, the output terminal of the module is short-circuited, and the module is scanned in real time under preset irradiance and irradiance non-uniformity conditions. The cell with the highest temperature at the edge of the module is marked as 1#, at least two other cells with the highest temperature besides 1# are marked as 2# and 3#, and the cell with the lowest temperature is marked as 4#. 1#, 2#, 3# and 4# are marked as target hot spot cells.
[0010] Furthermore, when determining the optimal shading area, the selected battery cells are sequentially shaded at multiple preset ratios along the direction perpendicular to the main grid of the battery. The hottest area of the battery is not shaded during the shading process. After each shading, a preset time is waited for the battery temperature to stabilize. The highest temperature of the battery is measured at different shading areas, and the shading area with the highest temperature is taken as the optimal shading area.
[0011] Furthermore, after shading the selected solar cells according to the optimal shading area, the module is short-circuited and placed in an irradiation environment for a first preset time. During the exposure, the module temperature is kept within a preset range. If the solar cell temperature still rises after the first preset time, the exposure continues for a second preset time.
[0012] Furthermore, the bypass diode function verification includes temperature gradient testing and reverse bias triggering verification. The temperature gradient testing involves adjusting the ambient temperature to multiple preset temperature gradients, stabilizing at each temperature for a preset time, applying short-circuit currents of different multiples to the component, and measuring the forward voltage and temperature rise of the bypass diode. The reverse bias triggering verification involves maintaining the target battery in a shaded state, connecting the component to a simulated load circuit, adjusting the load current to exceed the maximum photocurrent of the shaded target battery, and causing the target battery to enter a reverse bias state.
[0013] Furthermore, after the hot spot durability test, the component was placed in a set temperature environment to cool for a preset time, and the electrical performance parameters of the component were tested again under standard test conditions. Electroluminescence was used for detection, and the results were compared with the initial test results.
[0014] Furthermore, the standards for evaluating component performance include: maximum power attenuation not exceeding a preset threshold, no significant abnormalities in short-circuit current and open-circuit voltage, no burning, melting, cracking, delamination, backsheet carbonization, junction box deformation, or broken lead wires on the component appearance, and the bypass diodes functioning normally without burnout or adhesion failure.
[0015] Furthermore, in the irradiation conditions, the irradiation intensity of the single-glass module is within a first preset range, the irradiation intensity of the double-sided module is within a second preset range, and the module temperature is maintained within a preset range.
[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages: This method first tests the initial electrical performance data of the photovoltaic module to provide a benchmark for subsequent comparisons. Next, the module's output terminal is short-circuited, and the module is scanned under irradiation conditions to select target hotspot cells and control cells. By short-circuiting to bring the branch current to the short-circuit current value, cells with actual hotspot risks can be quickly screened under irradiation conditions, avoiding the cumbersome cell selection process of individually shading each cell with different proportions, as required by existing technologies. Then, the module is short-circuited again, and the selected cells are tested for shading ratios under irradiation conditions to determine the optimal shading area. After shading according to this area, the module is short-circuited and placed in an irradiation environment for hotspot durability exposure, while the temperature of the hotspot cells is recorded. By verifying the functionality of the bypass diode, it can be ensured that the bypass diode can conduct normally when hotspots occur, thereby cutting off the reverse-biased cells from the circuit. This makes the test conditions closer to the actual operating conditions of the module connected to a load or inverter with the bypass diode functioning normally. After the hot spot durability test, the module is restored to its initial state and its electrical performance parameters are tested again. The results are then compared with the initial data to evaluate the module's performance. Compared with existing technologies, this method improves testing efficiency, makes the testing conditions closer to actual operating conditions, and avoids the problems of excessively high hot spot temperatures, easy module failure after testing, and limited reference value of temperature data caused by simply relying on short-circuiting methods in existing technologies.
[0017] Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In addition, the dimensions or spacing between the components are exaggerated to show the position of each component, and the schematic diagrams are for illustrative purposes only.
[0019] Figure 1 This is a flowchart of the method provided in an embodiment of the present invention; Detailed Implementation It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0020] Terminology Explanation: Solar photovoltaic (PV) modules: PV modules are the core component of a photovoltaic (PV) power generation system and also the most valuable part. Their function is to convert solar energy into electrical energy, which can then be either stored in batteries or used to power loads.
[0021] Hot spot durability of solar cell modules: Defects in some individual cells of a photovoltaic module may cause localized heating during operation, a phenomenon known as the "hot spot effect".
[0022] Over long-term use, birds, dust, fallen leaves, and other obstructions inevitably accumulate, casting shadows on photovoltaic (PV) modules. In large PV arrays, inappropriate row spacing can also cause shadows to form between modules. Due to these localized shadows, the current and voltage of certain individual cells within the PV module change, increasing the product of current and voltage in those areas and resulting in localized temperature increases. Defects in some individual cells can also cause localized heating during operation; this phenomenon is called the "hot spot effect."
[0023] In practical applications of solar cells, if the temperature generated by the hot spot effect exceeds a certain limit, it will melt the solder joints on the cell module and damage the grid lines, thus rendering the entire photovoltaic module unusable. Statistics show that the hot spot effect reduces the actual lifespan of photovoltaic modules by at least 10%.
[0024] Hot spot phenomena are unavoidable, although the effects of shading must be considered during photovoltaic module installation, and protective devices must be added to reduce the impact of hot spots. To demonstrate that solar cells can be used long-term under specified conditions, photovoltaic modules need to be tested through reasonable time and processes to determine their ability to withstand the heating effects of hot spots.
[0025] Existing testing methods are cumbersome in selecting photovoltaic modules, and there is a mismatch between the test conditions and actual usage conditions. Furthermore, the hot spot temperature obtained by short-circuiting the photovoltaic modules is too high, which may even cause the photovoltaic modules to fail after testing. In addition, the hot spot temperature obtained is not very meaningful.
[0026] To address the aforementioned issues, the method provided in this embodiment includes module pretreatment, module electrical performance testing, initial defect screening, module cell selection, hot spot durability testing, bypass diode function verification, post-test performance judgment and result evaluation. This method can quickly select cells in the tested module that are at risk of hot spots under different irradiation intensities. By employing bypass diode function verification, the effectiveness of the bypass diode is effectively verified. The operation is simple and quick, and more closely approximates the operating conditions of photovoltaic modules.
[0027] The main steps of the photovoltaic module hot spot durability test method are as follows: Test the initial electrical performance data of photovoltaic modules, and establish a test benchmark through the initial electrical performance data test.
[0028] By short-circuiting the module's output terminal and scanning the module under irradiation conditions, target hot spot cells and control cells can be selected. By short-circuiting the module's output terminal and combining it with irradiation scanning to select target hot spot cells and control cells, cells with potential hot spot risks can be quickly located.
[0029] The module is short-circuited, and a shading ratio test is performed on selected solar cells under irradiation conditions to determine the optimal shading area. The selected solar cells are then shaded according to the optimal shading area. After short-circuiting the module, it is placed in an irradiation environment for hot spot durability exposure, and the temperature of the hot spot solar cells is recorded. The optimal shading area is determined through the shading ratio test, ensuring the test conditions closely resemble the actual operating conditions of the module. Conducting hot spot durability exposure and recording the temperature after determining the shading area provides accurate and effective hot spot temperature data. In this method, short-circuiting is primarily used in the cell selection and optimal shading area determination stages, and a bypass diode function verification step is subsequently included.
[0030] The bypass diode function of the component is verified to ensure the effectiveness of the component's protection devices.
[0031] After the hot spot durability test is completed, the module is restored to its initial state, the electrical performance parameters of the module are tested and compared with the initial electrical performance data to evaluate the module performance and achieve an objective assessment of the module's durability performance.
[0032] Furthermore, the photovoltaic modules undergo pretreatment before testing to bring them to a thermally stable state. This eliminates inconsistencies in the initial state of the modules due to differences in storage or transportation environments before testing, thereby ensuring the accuracy and repeatability of subsequent tests. The pretreatment includes placing the modules in an environment with set temperature and humidity for a predetermined time, and ensuring the bypass diodes are correctly wired. This prevents the bypass diodes from malfunctioning during testing due to incorrect wiring, which could affect the reliability of hot spot durability testing and bypass diode functional verification.
[0033] Furthermore, before selecting the target hot spot battery and the control battery, an initial defect check is performed on the components to exclude components with initial defects; the initial defect check includes scanning the surface of the components to record the initial temperature distribution and using electroluminescence to detect the internal state of the battery cells.
[0034] Infrared scanning records the initial temperature distribution, eliminating modules with inherent defects such as microcracks, poor soldering, or dark cracks, thus preventing temperature anomalies caused by non-hotspot factors from interfering with subsequent test results. Electroluminescence detection allows observation of the cell's luminescence state from within, further confirming the presence of initial failure points. These two detection methods work together to screen modules from two dimensions: external temperature distribution and internal electroluminescence characteristics. This ensures that modules entering subsequent tests are in a good initial state, allowing the hotspot durability test results to accurately reflect the module's resistance to hotspot effects.
[0035] Furthermore, when selecting target hot spot cells and control cells, the output terminal of the module is short-circuited, and the module is scanned in real time under preset irradiance and irradiance non-uniformity conditions. The cell with the highest temperature at the edge of the module is marked as 1#, at least two other cells with the highest temperature besides 1# are marked as 2# and 3#, and the cell with the lowest temperature is marked as 4#. 1#, 2#, 3# and 4# are marked as target hot spot cells.
[0036] When the module's output current equals the short-circuit current under short-circuit conditions, the shaded solar cells are more likely to enter a reverse bias state, thus generating heat. Real-time infrared scanning can accurately identify solar cells with the true risk of hot spots. The solar cell with the highest edge temperature is selected as the target for the highest hot spot risk, supplemented by other solar cells with the highest temperatures, while the lowest temperature solar cell is selected as a control. This multi-point selection method ensures both the relevance of the test and provides a reference for temperature comparison.
[0037] Furthermore, when determining the optimal shading area, the selected battery cells are sequentially shaded at multiple preset ratios along the direction perpendicular to the main grid of the battery. The hottest area of the battery is not shaded during the shading process. After each shading, a preset time is waited for the battery temperature to stabilize. The highest temperature of the battery is measured at different shading areas, and the shading area with the highest temperature is taken as the optimal shading area.
[0038] The shading method along the vertical direction of the cell's main grid simulates the distribution of shadows along the length of the cell in actual use. The hottest area of the cell is not shaded to avoid the shading itself affecting the temperature measurement of the hot spot area. Temperature is measured only after a preset time has elapsed to allow the cell to heat up and stabilize, ensuring the accuracy of the temperature data. By comparing the highest temperatures under different shading ratios, the shading ratio that causes the most severe hot spot effect is identified. This ratio is then used as the shading condition for subsequent durability tests, ensuring that the test conditions cover the most severe shading situations that the module might encounter in actual use.
[0039] Furthermore, after shading the selected solar cells according to the optimal shading area, the module is short-circuited and placed in an irradiation environment for a first preset time. During the exposure, the module temperature is kept within a preset range. If the solar cell temperature still rises after the first preset time, the exposure continues for a second preset time.
[0040] By using segmented exposure methods, the test duration can be guaranteed to meet standard requirements. Furthermore, by monitoring temperature changes, adjustments can be made to extend the exposure time, allowing the test to adapt to the thermal characteristics of different components. For components with slower thermal response or larger heat capacity, extending the exposure time ensures that the hot spot temperature reaches a stable state, thus enabling a more accurate assessment of the component's hot spot tolerance.
[0041] Furthermore, the bypass diode function verification includes temperature gradient testing and reverse bias triggering verification; the temperature gradient testing involves adjusting the ambient temperature to multiple preset temperature gradients, stabilizing at each temperature for a preset time, applying short-circuit current of different multiples to the component, and measuring the forward voltage and temperature rise of the bypass diode, thereby verifying whether the bypass diode can conduct normally under different ambient temperatures and whether its conduction characteristics meet the requirements.
[0042] The reverse bias trigger verification is as follows: retain the target battery's shaded state, connect the component to the simulated load circuit, adjust the load current so that the current value exceeds the maximum photocurrent of the shaded target battery, so that the target battery enters the reverse bias state. At this time, the bypass diode should be triggered to conduct in order to protect the battery cell.
[0043] These two verifications confirm the functionality of the bypass diode from the aspects of temperature adaptability and reverse bias triggering conditions, respectively, to ensure that the diode can work effectively when hot spots occur and to avoid damage to the component due to the hot spot effect.
[0044] Furthermore, after the hot spot durability test, the component was placed in a set temperature environment to cool for a preset time, and the electrical performance parameters of the component were tested again under standard test conditions. Electroluminescence was used for detection, and the results were compared with the initial test results.
[0045] The retesting method ensures consistency of testing conditions before and after the test, enabling the comparison of electrical performance parameters to accurately reflect the impact of hotspot durability testing on module performance. Comparison of electroluminescence detection results with the initial detection results can determine whether new defects such as microcracks, broken grids, or poor solder joints have appeared in the module after testing, assessing the damage to the module from an internal structural perspective.
[0046] Furthermore, the standards for evaluating component performance include: maximum power attenuation not exceeding a preset threshold, no significant abnormalities in short-circuit current and open-circuit voltage, no burning, melting, cracking, delamination, backsheet carbonization, junction box deformation, or broken lead wires on the component appearance, and the bypass diodes functioning normally without burnout or adhesion failure.
[0047] These evaluation criteria comprehensively assess the component's condition after hot spot durability testing from three dimensions: electrical performance, appearance and structure, and bypass diode function. For electrical performance, maximum power attenuation is used as the primary quantitative indicator, with short-circuit current and open-circuit voltage serving as supplementary criteria. The appearance and structure assessment covers various physical damages that may be caused by the hot spot effect. The bypass diode function focuses on protecting the integrity of the device itself. These three dimensions of evaluation criteria complement each other, forming a complete set of criteria for qualification.
[0048] Furthermore, in the irradiation conditions, the irradiation intensity of the single-glass module is within a first preset range, the irradiation intensity of the double-sided module is within a second preset range, and the module temperature is maintained within a preset range to ensure the stability of the module temperature during the test and avoid temperature fluctuations affecting the measurement results of the hot spot temperature.
[0049] like Figure 1 As shown, the specific steps of the test method are as follows: S100 component preprocessing.
[0050] Select qualified photovoltaic module samples to ensure that the appearance is undamaged, the junction box is secure, and the bypass diode is correctly wired.
[0051] Place the module in an environment of 25℃±2℃ and relative humidity≤70% for at least 24 hours to allow the module to reach a thermally stable state.
[0052] S200 module electrical performance test.
[0053] Under STC standard conditions (1000W / m², AM1.5 spectrum, module temperature 25±2℃), the IV curve of the module was tested using an AAA-grade solar simulator, and key parameters were recorded: maximum power Pmax1, short-circuit current Isc1, open-circuit voltage Voc1, and fill factor FF1, which served as a benchmark for performance comparison before and after the test.
[0054] S300 initial defect investigation.
[0055] Use an infrared thermal imager to scan the surface of the components and record the initial temperature distribution to exclude components with inherent defects such as microcracks, poor soldering, and dark cracks. Use an EL electroluminescence analyzer to test the internal state of the solar cell to ensure there are no initial failure points, and record it as EL1.
[0056] S400 component selection.
[0057] Short-circuit the module output terminal to ensure the branch current equals the short-circuit current. Turn on the solar simulator, stabilize the irradiance at 700W / m²±5%, irradiance non-uniformity ≤±2%, and the spectrum conforms to AM1.5. Use an infrared thermal imager to scan the module in real time, select the cell with the highest temperature at the module edge and mark it as #1; select the other two cells (excluding #1) with the highest temperatures and mark them as #2 and #3; select the cell with the lowest temperature and mark it as #4. Mark #1-#4 as the "target hotspot cells".
[0058] S500 hot spot durability test.
[0059] S510 short-circuited the components and exposed them to sunlight without any obstruction, with the solar simulator irradiance adjusted to 1000 W / m². 2 ±10%, the irradiance requirement for bifacial modules is BSI ±50W / m 2 The component temperature is maintained at 55±10℃.
[0060] The S520 sequentially blocks the selected battery cells along the direction perpendicular to the main grid of the battery (without blocking the hottest area of the battery) by 10%, 20%, 30%, etc., and waits for 10±5 minutes to allow the battery to heat up and remain stable. The highest temperature of the battery at different blocking areas is measured and recorded using an infrared thermal imager; the blocking area with the highest temperature is the optimal blocking area.
[0061] Based on the optimal shading area determined by S530, the selected solar cells are shaded to maintain their maximum power consumption (excluding the hottest areas of the cells). The module is then short-circuited and exposed to sunlight for 1 hour. The required irradiance for a single-glass module is 1000±50W / m². 2 The required irradiance for bifacial modules is BSI ± 50 W / m². 2 During the process, the temperature of the components is maintained at 55±10℃.
[0062] The S540 uses an infrared thermal imager to collect and record the highest temperature of the hot spot solar cell; it then sequentially exposes and tests selected solar cells; if the cell temperature still rises after 1 hour of irradiation exposure, it continues irradiation exposure for another 5 hours.
[0063] S600 bypass diode function verification.
[0064] 6.6.1 Temperature gradient test: Adjust the ambient temperature to four gradients: 30℃, 50℃, 70℃, and 90℃, and stabilize at each temperature for 30 minutes; apply currents of 1.0 times and 1.25 times Isc to the component, and measure the forward voltage and temperature rise of the bypass diode to ensure that the diode can conduct normally at each temperature.
[0065] 6.6.2 Reverse Bias Trigger Verification: Maintain the target cell's shaded state and connect the module to a simulated load circuit. Adjust the load current, gradually increasing the branch current until the current value exceeds the maximum photocurrent of the shaded target cell. At this point, the target cell will be forced into a reverse bias state due to "insufficient power supply," and its terminals will exhibit a reverse voltage.
[0066] S700 Post-Test Performance Determination and Result Evaluation.
[0067] S710 Sample Cooling and Retesting: After the test, remove the shielding template and short-circuit device, and place the component in an environment of 25℃±2℃ to cool for 24 hours to restore it to its initial state.
[0068] Test the component IV curve again under STC conditions, compare the electrical performance parameters before and after the test, and record the key parameters: maximum power Pmax2, short-circuit current Isc2, open-circuit voltage Voc2, and fill factor FF2.
[0069] Visual inspection: Check the appearance of the components for irreversible damage such as burning, melting, cracking, delamination, backplate carbonization, junction box deformation, and broken leads. The results were recorded again using an infrared thermal imager and an EL tester. Compared with EL1, EL2 showed no new defects such as hidden cracks, broken grids, or poor solder joints.
[0070] S720 pass / fail criteria: Electrical performance: Maximum power attenuation ≤5%, Isc and Voc show no significant abnormalities; Appearance and structure: No irreversible damage as described above; Bypass diode: Functioning normally, with no burnout or adhesion failure.
[0071] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.
Claims
1. A method for testing the hot spot durability of photovoltaic modules, characterized in that, Includes the following steps: Test the initial electrical performance data of photovoltaic modules; Short-circuit the output of the module, scan the module under irradiation conditions, and select the target hot spot cell and the control cell; Short-circuit the module and test the shading ratio of the selected cells under irradiation conditions to determine the optimal shading area; shade the selected cells according to the optimal shading area, short-circuit the module and place it in the irradiation environment for hot spot durability exposure, and record the temperature of the hot spot cells. Verify the bypass diode function of the component; After the hot spot durability test is completed, the module is restored to its initial state, and the electrical performance parameters of the module are tested and compared with the initial electrical performance data to evaluate the module performance.
2. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, Before testing, the photovoltaic modules are pretreated to achieve a thermally stable state. The pretreatment includes placing the modules in an environment with a set temperature and humidity for a preset time and ensuring that the bypass diodes are connected correctly.
3. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, Before selecting the target hot spot battery and the control battery, an initial defect check is performed on the components to exclude components with initial defects. The initial defect check includes scanning the surface of the component to record the initial temperature distribution and using electroluminescence to detect the internal state of the battery cells.
4. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, When selecting target hot spot cells and control cells, the output terminal of the module is short-circuited, and the module is scanned in real time under preset irradiance and irradiance non-uniformity conditions. The cell with the highest temperature at the edge of the module is marked as 1#, at least two other cells with the highest temperature besides 1# are marked as 2# and 3#, and the cell with the lowest temperature is marked as 4#. 1#, 2#, 3# and 4# are marked as target hot spot cells.
5. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, When determining the optimal shading area, the selected battery cells are sequentially shaded along the direction perpendicular to the main grid of the battery in multiple preset proportions. The hottest area of the battery is not shaded during the shading. After each shading, a preset time is waited for the battery temperature to stabilize. The highest temperature of the battery is measured at different shading areas, and the shading area with the highest temperature is taken as the optimal shading area.
6. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, After shading the selected solar cells according to the optimal shading area, the module is short-circuited and placed in the irradiation environment for a first preset time. During the exposure, the module temperature is kept within a preset range. If the solar cell temperature still rises after the first preset time, the exposure continues for a second preset time.
7. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, The bypass diode functional verification includes temperature gradient testing and reverse bias triggering verification. The temperature gradient testing involves adjusting the ambient temperature to multiple preset temperature gradients, stabilizing at each temperature for a preset time, applying short-circuit currents of different multiples to the component, and measuring the forward voltage and temperature rise of the bypass diode. The reverse bias triggering verification involves maintaining the target cell in a shaded state, connecting the component to a simulated load circuit, adjusting the load current to exceed the maximum photocurrent of the shaded target cell, and causing the target cell to enter a reverse bias state.
8. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, After the hot spot durability test is completed, the component is placed in a set temperature environment to cool for a preset time. The electrical performance parameters of the component are then tested again under standard test conditions, and electroluminescence is used for detection, which is compared with the initial test results.
9. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, The standards for evaluating component performance include: maximum power attenuation not exceeding a preset threshold, no significant abnormalities in short-circuit current and open-circuit voltage, no burning, melting, cracking, delamination, backsheet carbonization, junction box deformation, or broken lead wires on the component appearance, and normal function of bypass diodes without burnout or adhesion failure.
10. The photovoltaic module hot spot durability testing method as described in claim 1, characterized in that, In the irradiation conditions, the irradiation intensity of the single-glass module is within a first preset range, the irradiation intensity of the bifacial module is within a second preset range, and the module temperature is maintained within a preset range.