Method and system for evaluating performance of decommissioned photovoltaic modules

Abstract

The application discloses a kind of performance evaluation methods and systems of decommissioned photovoltaic module, it is related to photovoltaic module detection technical field, including, the surface dry state baseline of decommissioned photovoltaic module is obtained and configuration collection channel is collected, under the condition that meeting stable condition, power output test is carried out, voltage, current are collected and maximum power and fill factor are obtained, power data are irradiance and temperature normalization to generate power data with time stamp and working condition field;Under the premise that installation posture and grounding condition remain unchanged, insulation pressure test is implemented by wet heat trigger factor, and insulation data bound with power data timestamp are generated;Power data and insulation data are calculated by joint criterion, and performance evaluation grade is obtained, the collaborative evaluation of output capability and electrical safety state of decommissioned photovoltaic module is realized.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module testing technology, and in particular to a method and system for evaluating the performance of retired photovoltaic modules. Background Technology

[0002] As the installed capacity of photovoltaic (PV) power generation continues to expand, early-stage PV modules are gradually entering the retirement phase. For the performance evaluation of retired PV modules, existing technologies typically employ a power output testing-based approach. This involves collecting current and voltage data under specific operating conditions, calculating electrical parameters such as maximum power, and converting the test results to standard reference conditions to determine the module's output capacity and reuse value. Simultaneously, some evaluation methods supplement this with visual inspection, insulation resistance testing, or withstand voltage testing to determine whether the module meets basic electrical safety requirements. These evaluation methods have been widely used in PV module testing and grading, providing an important technical foundation for the initial screening and performance assessment of retired modules.

[0003] However, as the service life of photovoltaic modules increases, their performance degradation characteristics gradually exhibit a multi-dimensional and asynchronous evolution pattern. On the one hand, there is not always a linear relationship between power output capacity and aging of the internal packaging and deterioration of the backsheet. It is difficult to fully reflect the electrical condition of the module based solely on power indicators. On the other hand, traditional insulation tests are mostly conducted under different operating conditions or time conditions than power tests. The test results lack unified operating condition constraints and time correlations, making it difficult to form an effective correspondence between power output results and insulation safety status. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for evaluating the performance of decommissioned photovoltaic modules, which solves the problems of difficulty in uniformly representing power evaluation and insulation safety status, and lack of correlation between evaluation results and operating conditions in the existing technology.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a method for performance evaluation of decommissioned photovoltaic (PV) modules, comprising: acquiring a surface dry baseline for the decommissioned PV module to be evaluated while maintaining consistent module mounting posture, clamping position, and frame grounding conditions, and simultaneously configuring and initializing the acquisition channel; performing a power output test on the decommissioned PV module under stable operating conditions, acquiring voltage and current, and obtaining the maximum power and fill factor; normalizing the power output data according to irradiance and temperature to generate power data with timestamps and operating condition fields; while maintaining unchanged mounting posture and grounding conditions, creating a humid and hot state on the backsheet of the decommissioned PV module using a damp heat triggering factor, performing an insulation pressure test on the decommissioned PV module, continuously acquiring leakage current changes and calculating dynamic insulation characteristic parameters to generate insulation data bound to the power data timestamps; and when the power data and insulation data meet the conditions of timestamp binding and operating condition consistency, performing a joint criterion calculation on the power data and insulation data to obtain a comprehensive evaluation value and generate the performance evaluation level of the decommissioned PV module to be evaluated.

[0008] As a preferred embodiment of the performance evaluation method for decommissioned photovoltaic modules described in this invention, the method for obtaining the surface dry baseline includes: performing non-destructive cleaning treatment on the decommissioned photovoltaic module to bring the front and back sides of the decommissioned photovoltaic module into a dry and stable state; and based on the dry and stable state, collecting the surface dry baseline characterizing the electrical state of the backsheet surface of the decommissioned photovoltaic module at the sampling location.

[0009] As a preferred embodiment of the performance evaluation method for decommissioned photovoltaic modules described in this invention, the configuration of the acquisition channels includes configuring an irradiance acquisition channel and a temperature acquisition channel before conducting power output testing on the decommissioned photovoltaic modules; the initialization includes correcting the acquired irradiance data and temperature data based on the channel calibration factors of the irradiance acquisition channel and the temperature acquisition channel to obtain corrected irradiance and corrected temperature.

[0010] As a preferred embodiment of the performance evaluation method for retired photovoltaic modules described in this invention, the condition of satisfying the stable operating conditions includes determining the stability of the rectified irradiance and the rectified temperature within a time window. When both the irradiance change and the temperature change meet the stability threshold, the time window is determined as the power test window.

[0011] As a preferred embodiment of the performance evaluation method for retired photovoltaic modules described in this invention, the power output test of the retired photovoltaic modules includes: collecting voltage and current data of the retired photovoltaic modules, and calculating the maximum power, open-circuit voltage, short-circuit current, and fill factor based on the collected voltage and current; the maximum power and fill factor are used as characterization parameters of the power output capability of the retired photovoltaic modules.

[0012] As a preferred embodiment of the performance evaluation method for retired photovoltaic modules described in this invention, the normalization of power output data based on irradiance and temperature includes correcting the measured maximum power to standard reference irradiance and standard reference temperature based on the average irradiance and average temperature within the power test window, thereby obtaining normalized power data.

[0013] As a preferred embodiment of the performance evaluation method for decommissioned photovoltaic modules described in this invention, the insulation pressure test of the decommissioned photovoltaic module using a damp heat triggering factor includes: humidifying the outer surface of the backsheet of the decommissioned photovoltaic module to form a wet coverage state while maintaining the installation posture, clamping method, and grounding conditions of the decommissioned photovoltaic module; heating the backsheet of the decommissioned photovoltaic module after the wet coverage state is formed, so that the backsheet is in a damp heat triggering condition; applying an insulation test voltage to the decommissioned photovoltaic module under the damp heat triggering condition, continuously collecting leakage current data during the pressure application process, and calculating dynamic insulation parameters based on the test voltage and leakage current; the dynamic insulation parameters include the minimum insulation resistance during the holding phase, the steady-state insulation resistance at the end of the holding phase, the leakage conductance integral characteristic during the holding phase, the peak count during the holding phase, and the dynamic decay constant during the holding phase.

[0014] As a preferred embodiment of the performance evaluation method for decommissioned photovoltaic modules described in this invention, the damp heat triggering factor refers to applying a wet state to the outer surface of the decommissioned photovoltaic module and superimposing a hot state to maintain it, so that the backsheet of the decommissioned photovoltaic module is in a damp heat state under wet state consistency conditions and temperature stability conditions, and an insulation pressure test is performed under the damp heat state to obtain dynamic insulation characteristic parameters.

[0015] As a preferred embodiment of the performance evaluation method for decommissioned photovoltaic modules described in this invention, the step of jointly calculating the power data and insulation data includes combining normalized power data, fill factor, and dynamic insulation parameters; calculating a comprehensive evaluation index based on the combination; and generating a performance evaluation level for the decommissioned photovoltaic module according to the comprehensive evaluation index and the level classification rules.

[0016] Secondly, this invention provides a performance evaluation system for decommissioned photovoltaic (PV) modules, comprising an initialization module, a power output module, a power normalization module, an insulation testing module, and a joint criterion module. The initialization module is responsible for acquiring the surface dry-state baseline of the decommissioned PV module to be evaluated, configuring the acquisition channel, and initializing it. The power output module is responsible for performing power output testing on the decommissioned PV module under stable operating conditions, acquiring voltage and current, and obtaining the maximum power and fill factor. The power normalization module is responsible for normalizing the power output data according to irradiance and temperature, generating power data with timestamps and operating condition fields. The insulation testing module is responsible for implementing insulation stress testing on the decommissioned PV module using a damp heat triggering factor, continuously acquiring leakage current changes and calculating dynamic insulation characteristic parameters, generating insulation data bound to the power data timestamps. The joint criterion module is responsible for performing joint criterion calculations on the power data and insulation data to generate the performance evaluation level of the decommissioned PV module to be evaluated.

[0017] The beneficial effects of this invention are as follows: by implementing power output testing and dynamic insulation assessment under the same timestamp constraint, the corresponding characterization of power output capability and electrical safety status under the same operating conditions is achieved; by combining the damp heat triggering factor before and after the power test and conducting insulation pressure testing under damp heat stable conditions, the electrical safety boundary status of retired photovoltaic modules under typical high humidity and high temperature operating environments is effectively characterized; by combining the operating condition consistency judgment during the assessment process, the traceability and verifiability of the assessment data are achieved; and through comprehensive evaluation criteria, the graded judgment of the performance status of retired photovoltaic modules is achieved, providing an intuitive and operable assessment basis for module reuse, sorting, and risk management. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart for the performance evaluation method of retired photovoltaic modules.

[0020] Figure 2 A schematic diagram of a performance evaluation system for retired photovoltaic modules.

[0021] Figure 3 This is a flowchart for the power output test.

[0022] Figure 4 This is a flowchart for damp heat-triggered insulation stress test.

[0023] Figure 5 This is a comparison graph of multiple leakage current curves. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0027] Reference Figures 1-5 As one embodiment of the present invention, this embodiment provides a method for evaluating the performance of decommissioned photovoltaic modules, including the following steps:

[0028] S1. For the retired photovoltaic modules to be evaluated, while maintaining the same module installation posture, clamping position and frame grounding conditions, obtain the surface dry baseline and simultaneously configure and initialize the acquisition channel.

[0029] Furthermore, a unique identifier is generated for each photovoltaic module to be evaluated for retirement; the unique identifier consists of an evaluation batch identifier, a module sequence identifier, and an anti-duplicate verification identifier.

[0030] It should be noted that the photovoltaic modules to be evaluated for retirement are retired crystalline silicon photovoltaic modules with aluminum frames and junction boxes.

[0031] Write the component nameplate information and structural information into the record table, including at least the rated power information, component model, manufacturing information, external dimensions information, output terminal type information, junction box type information, and aluminum frame type information.

[0032] Conduct a feasibility check on the retired photovoltaic modules and record the inspection results. If any structural defect affecting safe pressurization or reliable wiring is found during the feasibility check, write a termination code in the record table and end the performance evaluation of the current retired photovoltaic module; if no termination condition exists, continue.

[0033] Furthermore, the retired photovoltaic modules are installed on an adjustable attitude support, and the attitude parameters are evaluated according to standards to set the module attitude and generate attitude labels. The attitude labels are used to describe the module's tilt angle, orientation, and geometric relationship with the direction of light source incidence relative to the horizontal plane.

[0034] The clamping position and clamping method of the photovoltaic module are fixed according to the clamping geometry parameters, and a clamping position mark is generated. The clamping position mark is described by the module coordinate system. The coordinate axis is established along the long side and short side of the module with the lower left corner of the module as the origin, and the center coordinate of the clamp contact area is normalized.

[0035] Furthermore, a grounding clamp is installed at a designated unique grounding point on the aluminum frame to generate a grounding position mark; wherein, the grounding position mark is expressed in the component coordinate system and shares the same coordinate reference as the clamping position mark.

[0036] Connect the grounding clamp to the grounding terminal and measure the grounding loop resistance; the grounding loop resistance is the equivalent loop resistance from the grounding point on the frame through the grounding conductor to the ground terminal of the test equipment.

[0037] Furthermore, non-destructive cleaning is performed on the front glass and back sheet of the photovoltaic module to ensure that the front glass and back sheet of the photovoltaic module are in a dry baseline surface state.

[0038] Collect surface dry-state baseline quantities; wherein, the surface dry-state baseline quantities are repeatable surface state characterization quantities used to characterize the electrical conductivity of the backplane surface, and the measurement method can be achieved by any one of surface conductivity measurement, surface equivalent leakage measurement, and equivalent impedance measurement.

[0039] Record the timestamp of the dry baseline acquisition.

[0040] Furthermore, an irradiance acquisition channel is configured to acquire irradiance time series data, and the original irradiance measurement value is linearly corrected based on the irradiance channel calibration factor to obtain the corrected irradiance.

[0041] It should be noted that the irradiance channel calibration factor is determined by comparing the measurement output of the irradiance acquisition channel under standard irradiance conditions with the measurement results of a standard irradiance measurement device with metrological traceability, and based on the proportional relationship between the two. The value range is usually [0.95, 1.05].

[0042] Furthermore, a temperature acquisition channel is configured, including at least a rear temperature acquisition channel. Based on the temperature channel calibration factor, the rear temperature is linearly corrected to obtain the corrected rear temperature.

[0043] The cell temperature is estimated based on the corrected back-side temperature. Specifically, the corrected back-side temperature is corrected to the cell temperature estimate according to the temperature difference between the back-side and the cell.

[0044] It should be noted that the temperature channel calibration factor is a proportionality coefficient that minimizes the measurement deviation between the temperature acquisition channel and a traceable calibrated standard temperature sensor in a controlled reference environment. The value range is typically [0.98, 1.02].

[0045] Furthermore, a humidity acquisition channel is configured to obtain the time series of relative humidity on the back side; based on the humidity channel calibration factor, the original humidity measurement value is linearly corrected to obtain the corrected humidity.

[0046] It should be noted that the humidity channel calibration factor is determined by comparing the measurement output of the humidity acquisition channel with the measurement results of a standard humidity measurement device with metrological traceability in a controlled humidity environment, and based on the proportional relationship between the two. The value range is usually [0.95, 1.05].

[0047] Furthermore, a timestamp binding window is set and written to the record table; wherein, the timestamp binding window is used to constrain the maximum allowed time difference between the start timestamp of the power output test and the start timestamp of the dynamic insulation assessment.

[0048] Based on the timestamp binding window, a timestamp binding judgment rule is defined. Specifically, if the absolute value of the difference between the power output test start timestamp and the dynamic insulation assessment start timestamp does not exceed the timestamp binding window, the binding is judged as successful; otherwise, the binding is judged as unsuccessful.

[0049] Within each test window, irradiance stability statistics and temperature stability statistics are calculated. Specifically, the irradiance stability statistics are composed of the ratio of the difference between the maximum and minimum values ​​of the corrected irradiance within the timestamp-bound window to the average value; the temperature stability statistics are composed of the difference between the maximum and minimum values ​​of the estimated cell temperature within the timestamp-bound window.

[0050] Furthermore, consistency with the same operating condition is determined based on the obtained irradiance stability statistics and temperature stability statistics. Specifically, if the irradiance stability statistics and temperature stability statistics meet the consistency determination threshold constraints, the current test window is determined to meet the consistency requirement with the same operating condition; otherwise, it is determined not to meet the requirement.

[0051] It should be noted that the irradiance stability and consistency judgment threshold is determined based on the characteristic calibration results of the photovoltaic module power test sensitivity to irradiance fluctuations, so that the impact of irradiance changes on the power test results can be considered negligible within the irradiance stability and consistency judgment threshold range; the temperature stability and consistency judgment threshold is determined based on the characteristic calibration results of the photovoltaic module power output changing with cell temperature, so that the impact of temperature changes on the power test results is within an acceptable range within the temperature stability and consistency judgment threshold range.

[0052] S2. Under stable operating conditions, perform power output tests on retired photovoltaic modules, collect voltage and current data, and obtain the maximum power and fill factor.

[0053] Furthermore, the system continuously collects the corrected irradiance, the estimated cell temperature obtained from the back temperature calculation, and the corrected back humidity, and generates candidate power test windows in a sliding manner. The system then performs operating condition stability statistics and operating condition consistency judgment on each candidate window.

[0054] When the operating condition consistency determination result indicates that the current candidate window meets the operating condition stability conditions, the candidate window is locked as the power test window, and the power output test start timestamp is recorded. At the same time, the window identifier is written into the record table. If the operating condition stability conditions are not met, the window selection is continuously slid and the determination is repeated until a power test window that meets the conditions is obtained.

[0055] It should be noted that within the time window, the corrected irradiance and cell temperature are continuously monitored. When the changes in both meet the corresponding consistency threshold requirements, the time window is determined to be a stable operating condition.

[0056] After locking the power test window, reliably connect the component output terminal and the power output test equipment, and ensure that the positive and negative polarities are consistent; at the same time, keep the frame grounding conditions and grounding points consistent.

[0057] Furthermore, the power output test equipment is activated to perform current and voltage scanning, obtaining a discrete sequence composed of multiple sets of voltage and current sample values. The discrete sequence is then written into the data packet to be generated as the raw measurement data. During the scanning, irradiance, temperature, and humidity environmental sequence segments within the power test window are recorded synchronously, and the corresponding relationship of the window identifiers is marked in the record table to ensure that electrical measurements and environmental measurements can be aligned in the same time domain.

[0058] Furthermore, after obtaining the discrete voltage and current sequences, the discrete instantaneous power sequence is calculated point by point, and the maximum power is extracted as the measured maximum power; at the same time, the voltage and current corresponding to the maximum power are determined as the maximum power point.

[0059] Extract the open-circuit voltage and short-circuit current to obtain the measured open-circuit voltage and measured short-circuit current; then calculate the fill factor by dividing the measured maximum power by the product of the measured open-circuit voltage and measured short-circuit current. The fill factor and the maximum power point together serve as the core characterization field of power output capability and are written into the data packet.

[0060] The fill factor is expressed as:

[0061] ;

[0062] in, Indicates the fill factor. This indicates the measured maximum power. This indicates the measured open-circuit voltage. This indicates that the short-circuit current was measured.

[0063] S3. Normalize the power output data according to irradiance and temperature to generate power data with timestamp and operating condition fields.

[0064] Furthermore, the measured maximum power is normalized. Specifically, the normalization reference conditions are determined by the standard reference irradiance and the standard reference temperature.

[0065] Before normalization calculation, the average irradiance and average cell temperature estimate within the power test window are calculated first. The measured maximum power is then scaled to the standard reference irradiance according to the irradiance ratio. At the same time, the power change caused by the temperature deviation from the standard reference temperature is corrected according to the power temperature coefficient, thereby obtaining the normalized power index.

[0066] Normalized power calculation, expressed as:

[0067] ;

[0068] in, Represents normalized power. This indicates the measured maximum power. Indicates standard reference irradiance, Indicates the window average corrected irradiance. Indicates the power temperature coefficient. This represents the estimated average cell temperature within the window. Indicates the standard reference temperature.

[0069] It should be noted that the standard reference irradiance is selected from the general reference irradiance conditions used in the nominal power rating and testing and evaluation of photovoltaic modules; the power temperature coefficient is selected as a linear coefficient characterizing the change of the maximum power of the photovoltaic module with the temperature of the solar cells, and is primarily determined based on the parameters on the module nameplate; the standard reference temperature is selected as the general reference solar cell temperature used in the power testing and performance evaluation of photovoltaic modules.

[0070] Furthermore, after completing the calculation of electrical parameters and normalized power index, the end timestamp of the current and voltage scan is recorded, and the start and end timestamps are written into the power data packet as timestamp fields of the power data. The power data packet is then constructed, which includes at least the following fields: unique component identifier; start and end timestamps of power output test; power test window identifier; operating condition fields such as window average irradiance, window average cell temperature estimate, and window average back humidity; fixed condition fields such as installation posture, clamping position, and grounding position; grounding loop measurement result field; original voltage and current discrete sequence field; and calculation result fields such as measured maximum power, maximum power point, measured open circuit voltage, measured short circuit current, fill factor, and normalized power.

[0071] S4. Under the premise of keeping the installation posture and grounding conditions unchanged, a damp heat state is formed on the back sheet of the retired photovoltaic module by using a damp heat triggering factor. Insulation pressure test is carried out on the retired photovoltaic module, leakage current changes are continuously collected and dynamic insulation characteristic parameters are calculated, and insulation data bound to power data timestamp is generated.

[0072] Furthermore, based on the installation posture information, clamping position information, and frame grounding position information, the on-site assembly status was checked to confirm that the bracket posture had not been adjusted, the clamp position had not been moved, and the grounding clamp was still installed at the designated grounding point with continuous grounding conductor connection.

[0073] The grounding loop is retested to obtain the retested grounding loop resistance, and its consistency is compared with the grounding loop resistance.

[0074] If the grounding consistency threshold condition is met, the grounding consistency is passed; otherwise, the grounding consistency fails and the subsequent performance evaluation ends, and a termination code is written to the record table.

[0075] It should be noted that the grounding consistency threshold is determined by statistical analysis of repeated measurements of the evaluation device under standard grounding conditions, combined with the fluctuation range of typical field grounding conditions, and taking the grounding loop change limit that can cover measurement uncertainty and environmental disturbances. It is used to limit the grounding loop state before and after to be under equivalent conditions, thereby ensuring the comparability of power test and insulation test results.

[0076] Furthermore, while keeping the photovoltaic module installation posture unchanged, a humidifying medium is applied to the outer surface of the backsheet to make the backsheet wet-covered.

[0077] The wet coverage state refers to obtaining a repeatable water-containing coverage layer on the outer surface of the photovoltaic module backsheet by controlled humidification, while keeping the installation posture, clamping position and frame grounding conditions of the photovoltaic module unchanged. Specifically, water vapor or atomized droplets are applied to the outer surface of the photovoltaic module backsheet, so that the water forms a continuous but non-flowing coverage state on the backsheet surface. Subsequently, during natural diffusion and short-term static placement, the water spreads and seeps along the micro-texture, aging cracks and edge sealing areas of the backsheet surface, thereby constructing a stable wet surface environment.

[0078] After wet formation, wet surface state quantities are collected at the same sampling location as the dry baseline and using the same surface state measurement procedure. The wet surface state quantities and the dry baseline surface state quantities are then used to calculate the wet consistency index. The wet consistency index is used to determine whether the current wet formation has reached the reproducible target range.

[0079] The wet consistency index is expressed as:

[0080] ;

[0081] in, Indicates the wet consistency index, Represents the state quantity of a wet surface. This represents the surface state quantity of the dry baseline.

[0082] When the wetness consistency index meets the wetness threshold condition, the wetness formation is successful; if the wetness threshold condition is not met, the wetness coverage collection and judgment are repeated until successful.

[0083] It should be noted that the wet threshold is determined by comparing and analyzing the surface state changes of multiple batches of decommissioned photovoltaic modules under dry and humid conditions, selecting the range of changes that can stably trigger differences in insulation and leakage current with good repeatability as the judgment criterion.

[0084] Furthermore, under the premise of wet formation, a thermal triggering operation is applied to the outer surface of the backsheet to bring the backsheet temperature into the target temperature range and keep it stable during subsequent insulation pressure sampling.

[0085] It should be noted that the target temperature range is determined by calibrating and then curing based on the operating temperature range of the backsheet of the retired photovoltaic modules under typical outdoor high humidity operating conditions, combined with the stable controllable capability boundary given in the manufacturer's instructions for the heating device.

[0086] During the thermal triggering and maintenance process, the corrected back temperature and humidity are continuously collected to establish a humid heat window and generate a unique identifier for the humid heat window for traceability.

[0087] According to the defined operating condition consistency criteria, the temperature stability and humidity stability within the damp heat window are judged; only when the damp heat window meets the stability requirements is it allowed to enter the insulation pressure sampling.

[0088] Furthermore, connect the test circuit according to the insulation pressure wiring, that is, connect the output end of the photovoltaic module to the high-voltage end of the insulation pressure equipment, and connect the ground end of the aluminum frame to the ground end of the insulation pressure equipment; and ensure that the frame grounding remains at the predetermined grounding point and predetermined grounding circuit conditions.

[0089] Obtain the test voltage parameters and the set of pressure application timing parameters. The set of pressure application timing parameters uniquely defines the rise phase, the hold phase, and the discharge phase.

[0090] When the humid heat window stability conditions are met, the insulation pressure test is initiated, and the start and end timestamps of the insulation pressure test are recorded; the test voltage waveform and leakage current waveform are acquired synchronously throughout the pressure application process.

[0091] The acquired test voltage waveform and leakage current waveform are written into the record table as raw sequences and stored in association with the damp heat window identifier.

[0092] Furthermore, the leakage current collected during the pressure application process includes both displacement current and conductive leakage current.

[0093] In this embodiment, the equivalent capacitance is estimated first, the displacement current is estimated, and the conductive leakage current is obtained by subtracting the displacement current from the total leakage current; then the dynamic insulation resistance is obtained by dividing the test voltage by the conductive leakage current amplitude.

[0094] Meanwhile, to prevent the conductive leakage current from approaching zero and causing numerical instability, a lower limit protection is provided using a minimum current threshold constant.

[0095] The estimated displacement current is expressed as:

[0096] ;

[0097] in, This represents the estimated displacement current. Indicates equivalent capacitance. This indicates the test voltage waveform.

[0098] Conductive leakage current is expressed as:

[0099] ;

[0100] in, Indicates the leakage current. This represents the total leakage current waveform collected. This represents the estimated displacement current.

[0101] Dynamic insulation resistance is expressed as:

[0102] ;

[0103] in, Indicates dynamic insulation resistance. This indicates the test voltage waveform. Indicates the leakage current. This represents the minimum current threshold constant.

[0104] It should be noted that the equivalent capacitance is obtained by fitting the leakage current response during the voltage change phase of the insulation pressure application process. Specifically, during the pressure rise phase, the parameter inversion is performed using the proportional relationship between leakage current and voltage change rate, thereby determining the equivalent capacitance characterizing the equivalent electrical energy storage characteristics of the component under the current installation and wet conditions.

[0105] Furthermore, the dynamic insulation state is represented by a fixed set of parameters, which cannot be temporarily added or deleted according to the photovoltaic module type, in order to ensure consistency in batch evaluation.

[0106] The dynamic insulation parameters include the minimum insulation resistance during the holding phase, the steady-state insulation resistance at the end of the holding phase, the leakage conductance integral characteristics during the holding phase, the spike count during the holding phase, and the dynamic attenuation constant during the holding phase.

[0107] Furthermore, the minimum insulation resistance is expressed as:

[0108] ;

[0109] in, Indicates the minimum insulation resistance. Indicates dynamic insulation resistance. This indicates the time interval corresponding to the hold phase.

[0110] Steady-state insulation resistance is expressed as:

[0111] ;

[0112] in, Represents steady-state insulation resistance. This indicates that the end of the phase interval is maintained. This represents the time averaging operator.

[0113] The integral characteristic of leakage conductance is expressed as:

[0114] ;

[0115] in, This represents the integral characteristic of leakage conductance. Indicates the leakage current. This indicates the test voltage waveform. and These represent the start and end times of the hold phase.

[0116] Spike count, represented as:

[0117] ;

[0118] ;

[0119] in, The bandpass filter result represents the conductive leakage current. This represents the bandpass filter operator. and Indicates the filter bandwidth parameters. Indicates peak count, This represents the threshold parameter for peak amplitude. This represents the parameter for the peak persistence criterion. Indicates the duration of a single spike event. This indicates an indicator function.

[0120] It should be noted that the peak amplitude threshold parameter is determined by statistical analysis of the background noise level and transient fluctuation characteristics of the leakage current signal under insulation pressure conditions, so that the peak amplitude threshold can distinguish between random noise and transient conductivity anomalies with physical significance; the peak persistence criterion parameter is set according to the typical persistence characteristics of leakage current peaks on the time axis, and is used to exclude extremely short-term random disturbances and count only peak events that reflect real partial discharge or transient conductivity channels.

[0121] The dynamic decay constant is expressed as:

[0122] ;

[0123] in, The natural logarithm of dynamic insulation resistance. Indicates the fit intercept. Represents the dynamic decay constant. Indicates time.

[0124] It should be noted that the fitting intercept is obtained by performing linear regression on the logarithm of the dynamic insulation resistance and the time series within the fitting time interval. The value corresponds to the intercept of the regression line at the beginning of time and is used to characterize the initial level of the insulation state within the fitting interval.

[0125] Furthermore, the unique identifier of the photovoltaic module, the start and end timestamps of the insulation pressure test, the start timestamp of the damp heat trigger, the damp heat window identifier, the wet consistency index, the temperature and humidity statistics within the damp heat window, the grounding consistency check results, the test voltage waveform and leakage current waveform, the conductive leakage current and dynamic insulation resistance sequence, the equivalent capacitance, and the set of dynamic insulation characteristic parameters are encapsulated into an insulation data package; the insulation data package is calculated, verified, hashed, and stored.

[0126] The power test start timestamp in the power data packet and the insulation pressure start timestamp in the insulation data packet are time-stamp bound together. If the binding window parameter constraints are met, the binding is recorded as successful; otherwise, the binding is recorded as failed and a termination code is written.

[0127] In this embodiment, to verify the effective characterization of the electrical safety boundary state under typical high humidity and high temperature operating environments, an insulation pressure test voltage waveform was constructed for the same representative decommissioned photovoltaic module (the voltage amplitude remained at a constant value for about 3 seconds after the boost phase). Leakage current data was continuously collected at a fixed sampling frequency and a fixed insulation test window length, and the test was conducted under two operating conditions. The two operating conditions included a dry baseline condition (the backsheet surface was in a dry baseline state) and a damp heat triggered condition (first, a wet coverage state was formed on the outer surface of the backsheet, then it was heated to the target temperature and humidity of the damp heat triggered condition, and the insulation pressure test was performed under a damp heat stable state that met the wet consistency condition and the temperature stability condition, and the results were obtained as follows: Figure 5 The diagram shows a comparison of multiple leakage current curves.

[0128] Figure 5 To demonstrate the leakage current response curves of the same representative decommissioned photovoltaic module under the same insulation pressure test conditions in two operating conditions, curve A is the dry baseline and curve B is the damp heat triggering condition.

[0129] The results show that the overall current level of the damp-heat triggered operating condition curve is higher within the holding period, and more frequent and obvious transient spike fluctuations occur, reflecting the typical characteristics of enhanced surface conductive channels and weakened insulation boundaries under high humidity and high temperature environments. Since this experiment binds insulation data and power data under the same timestamp constraint and outputs data after the operating condition consistency judgment is passed, the leakage current difference can be regarded as the change in electrical safety status under the corresponding operating conditions. Dynamic insulation parameters can be further calculated, thereby achieving an effective characterization of the electrical safety boundary state of retired components under typical high humidity and high temperature operating environments, and ensuring that the evaluation data is traceable and verifiable.

[0130] S5. When the power data and insulation data meet the conditions of timestamp binding and operating condition consistency, the power data and insulation data are jointly calculated according to the criteria to obtain a comprehensive evaluation value and generate the performance evaluation level of the retired photovoltaic module to be evaluated.

[0131] Furthermore, the unique identifier field of the photovoltaic module is obtained from the power data and insulation data, and it is verified whether the two correspond to the same photovoltaic module; if they do not match, a termination code is written and the process ends.

[0132] Obtain the start timestamp of the power output test and the start timestamp of the insulation pressure test, and call the binding judgment rule for verification; if the binding judgment fails, write the termination code and end.

[0133] Obtain the operating condition consistency judgment results for the power test window and the insulation test window respectively. If necessary, verify whether the irradiance stability and temperature stability statistics meet the operating condition stability conditions. If either window does not meet the operating condition consistency requirements, write the termination code and end the test.

[0134] Obtain the wet consistency index and wet formation determination result; when the wet formation determination fails, write the termination code and end the process.

[0135] Furthermore, normalized power indices and fill factors are obtained from the power data; a set of dynamic insulation characteristic parameters is obtained from the insulation data; and the grounding loop resistance is obtained and verified to be consistent with the grounding conditions recorded during the power test phase.

[0136] The power-side and insulation-side indices are combined to form a joint vector, which is represented as:

[0137] ;

[0138] in, Denotes the joint vector. This indicates the resistance of the grounding loop.

[0139] Perform a normalization mapping on each vector in the joint vector to obtain the normalized set vector. .

[0140] It should be noted that the normalization mapping of each component in the joint vector adopts a monotonically saturated piecewise linear normalization mapping. Specifically, for each original feature dimension, the corresponding lower and upper bound anchor points are determined based on the training sample distribution that satisfies timestamp binding and working condition consistency, and the input feature values ​​are restricted within the anchor point interval. When the feature value is lower than the lower bound anchor point, it is directly mapped to the lower bound normalized value; when the feature value is higher than the upper bound anchor point, it is directly mapped to the upper bound normalized value. Within the anchor point interval, it is scaled linearly to a dimensionless value, thereby ensuring that features of different dimensions maintain a physically monotonically related relationship and have a stable saturation suppression effect on outliers and extreme values.

[0141] The comprehensive evaluation value is calculated based on the normalized set vector using a weighted difference criterion, and is expressed as follows:

[0142] ;

[0143] in, This represents the overall evaluation value. Represents the power-side normalized subvector. Represents the normalized sub-vectors for the insulation and grounding sides. Represents the power-side weight vector. This represents the weight vector for the insulation and grounding sides. This indicates the bias term.

[0144] It should be noted that the power-side weight vector, insulation and grounding-side weight vector, and bias term are determined through a constrained supervised learning method. Specifically, on a labeled sample set that satisfies timestamp binding and operating condition consistency, a binary classification cross-entropy loss function based on logistic regression is used for training, with reuse access availability and electric shock failure as supervision labels, respectively. During training, the power-side and insulation and grounding-side features are first subjected to monotonically saturated normalization mapping, and non-negativity, monotonicity, and lower bound protection constraints are applied to the weights. The weights and biases are iteratively optimized using the projected gradient descent algorithm. When the validation set loss converges and the gradient magnitude meets the stopping condition, the parameters are fixed, and finally, the weight vector and bias term that best match the comprehensive evaluation level boundary are obtained.

[0145] Furthermore, the comprehensive evaluation value is mapped to a performance evaluation level, expressed as:

[0146] ;

[0147] in, Indicates the performance evaluation level of the output. These represent different level identifiers. and These represent the grade boundary parameters of the comprehensive evaluation value.

[0148] It should be noted that the grade boundary parameters of the comprehensive evaluation value are... and By prioritizing the satisfaction of high-risk false negative rate constraints on the validation set, the upper boundary parameter is selected based on the comprehensive evaluation threshold that minimizes the false positive cost for the corresponding level. On the validation set, prioritizing the constraint of the false rejection rate of available components, the threshold value of the comprehensive evaluation value that minimizes the overall classification loss between low and medium levels is selected as the lower boundary parameter. .

[0149] Furthermore, the evaluation conclusion data is encapsulated and output, which includes at least the component's unique identifier, the start timestamps of the power output test and insulation stress test, the power condition window identifier and the insulation condition window identifier, the binding judgment result, the condition consistency judgment result, the joint vector set, the normalized vector set, the comprehensive evaluation value, and the performance evaluation level.

[0150] This embodiment also provides a performance evaluation system for retired photovoltaic modules, including: an initialization module, a power output module, a power normalization module, an insulation test module, and a joint criterion module.

[0151] The system comprises the following modules: an initialization module, responsible for acquiring the surface dry baseline of the decommissioned photovoltaic module to be evaluated, configuring the acquisition channel, and initializing it; a power output module, responsible for conducting power output tests on the decommissioned photovoltaic module under stable operating conditions, acquiring voltage and current, and obtaining the maximum power and fill factor; a power normalization module, responsible for normalizing the power output data according to irradiance and temperature, generating power data with timestamps and operating condition fields; an insulation testing module, responsible for implementing insulation pressure tests on the decommissioned photovoltaic module using a damp heat triggering factor, continuously acquiring leakage current changes and calculating dynamic insulation characteristic parameters, generating insulation data bound to the timestamps of the power data; and a joint criterion module, responsible for performing joint criterion calculations on the power data and insulation data to generate the performance evaluation level of the decommissioned photovoltaic module to be evaluated.

[0152] In summary, this invention achieves corresponding characterization of power output capability and electrical safety status under the same operating conditions by implementing power output testing and dynamic insulation assessment under the same timestamp constraint; by combining damp heat triggering factors before and after power testing and conducting insulation stress testing under damp heat stable conditions, it achieves effective characterization of the electrical safety boundary state of retired photovoltaic modules under typical high humidity and high temperature operating environments; by combining operating condition consistency judgment during the assessment process, it achieves traceability and verifiability of assessment data; and by using comprehensive evaluation criteria, it achieves graded judgment of the performance status of retired photovoltaic modules, providing an intuitive and operable assessment basis for module reuse, sorting, and risk management.

[0153] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for evaluating the performance of decommissioned photovoltaic modules, characterized in that: include, For the decommissioned photovoltaic modules to be evaluated, while maintaining the same module installation posture, clamping position, and frame grounding conditions, obtain the surface dry baseline and simultaneously configure and initialize the acquisition channel; Under stable operating conditions, power output tests were conducted on retired photovoltaic modules to collect voltage and current data, and to obtain the maximum power and fill factor. The power output data is normalized according to irradiance and temperature to generate power data with timestamps and operating condition fields; While maintaining the installation posture and grounding conditions, a damp heat state is created on the backsheet of the decommissioned photovoltaic module by using a damp heat triggering factor. Insulation pressure test is then performed on the decommissioned photovoltaic module, leakage current changes are continuously collected, dynamic insulation characteristic parameters are calculated, and insulation data bound to the power data timestamp is generated. When the power data and insulation data meet the conditions of timestamp binding and operating condition consistency, the power data and insulation data are jointly calculated according to the criteria to obtain a comprehensive evaluation value and generate the performance evaluation level of the retired photovoltaic module to be evaluated. The damp heat triggering factor refers to applying a wet state to the outer surface of the decommissioned photovoltaic module and superimposing a hot state to maintain it, so that the backsheet of the decommissioned photovoltaic module is in a damp heat state under wet state consistency conditions and temperature stability conditions, and an insulation pressure test is performed under the damp heat state to obtain dynamic insulation characteristic parameters. The insulation pressure test of the decommissioned photovoltaic module by the damp heat triggering factor includes humidifying the outer surface of the back sheet of the decommissioned photovoltaic module to form a wet coverage state while keeping the installation posture, clamping method and grounding conditions of the decommissioned photovoltaic module unchanged. After the wet cover condition is formed, the back sheet of the retired photovoltaic module is heated to put the module back sheet into a wet and hot trigger condition. Under damp and hot triggering conditions, an insulation test voltage is applied to the decommissioned photovoltaic modules, leakage current data is continuously collected during the pressure application process, and dynamic insulation parameters are calculated based on the test voltage and leakage current. The dynamic insulation parameters include the minimum insulation resistance during the holding phase, the steady-state insulation resistance at the end of the holding phase, the leakage conductance integral characteristic during the holding phase, the spike count during the holding phase, and the dynamic decay constant during the holding phase.

2. The performance evaluation method for decommissioned photovoltaic modules as described in claim 1, characterized in that: The process of obtaining the surface dry baseline includes performing non-destructive cleaning on the decommissioned photovoltaic modules to ensure that the front and back sides of the decommissioned photovoltaic modules are in a dry and stable state. Based on the dry and stable state, a surface dry-state baseline characterizing the electrical state of the backsheet surface of retired photovoltaic modules was collected at the sampling location.

3. The performance evaluation method for decommissioned photovoltaic modules as described in claim 1, characterized in that: The configuration of the acquisition channels includes configuring an irradiance acquisition channel and a temperature acquisition channel before conducting power output testing on retired photovoltaic modules; The initialization includes correcting the acquired irradiance and temperature data based on the channel calibration factors of the irradiance acquisition channel and the temperature acquisition channel to obtain the corrected irradiance and corrected temperature.

4. The performance evaluation method for decommissioned photovoltaic modules as described in claim 1, characterized in that: The conditions for meeting the stable operating conditions include determining the stability of the corrected irradiance and the corrected temperature within a time window. When both the irradiance change and the temperature change meet the stability threshold, the time window is determined as the power test window.

5. The performance evaluation method for decommissioned photovoltaic modules as described in claim 3, characterized in that: The power output test of the retired photovoltaic modules includes collecting voltage and current data of the retired photovoltaic modules, and calculating the maximum power, open-circuit voltage, short-circuit current and fill factor based on the collected voltage and current. The maximum power and fill factor are used as characterization parameters of the power output capability of retired photovoltaic modules.

6. The performance evaluation method for decommissioned photovoltaic modules as described in claim 1, characterized in that: The normalization process for the power output data based on irradiance and temperature includes correcting the measured maximum power to the standard reference irradiance and standard reference temperature based on the average irradiance and average temperature within the power test window, thereby obtaining normalized power data.

7. The performance evaluation method for decommissioned photovoltaic modules as described in claim 5, characterized in that: The calculation of the joint criteria for power data and insulation data includes combining normalized power data, fill factor, and dynamic insulation parameters; Based on the combined calculation of comprehensive evaluation indicators, and according to the comprehensive evaluation indicators and grading rules, the performance evaluation level of retired photovoltaic modules is generated.

8. A performance evaluation system for decommissioned photovoltaic modules, based on the performance evaluation method for decommissioned photovoltaic modules according to any one of claims 1 to 7, characterized in that: This includes an initialization module, a power output module, a power normalization module, an insulation test module, and a joint criterion module; The initialization module is responsible for acquiring the surface dry baseline of the decommissioned photovoltaic module to be evaluated, configuring the acquisition channel, and initializing it. The power output module is responsible for conducting power output tests on retired photovoltaic modules under stable operating conditions, collecting voltage and current, and obtaining the maximum power and fill factor. The power normalization module is responsible for normalizing the power output data according to irradiance and temperature, and generating power data with timestamp and operating condition fields. The insulation test module is responsible for conducting insulation stress tests on decommissioned photovoltaic modules through a damp heat triggering factor, continuously collecting leakage current changes and calculating dynamic insulation characteristic parameters, and generating insulation data bound to the power data timestamp. The joint criterion module is responsible for performing joint criterion calculations on power data and insulation data to generate the performance evaluation level of the decommissioned photovoltaic modules to be evaluated.

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