Energy efficiency evaluation method for long-span flexible high-support and bifacial module photovoltaic systems

Abstract

This invention relates to a method for energy efficiency evaluation of long-span flexible high-support and bifacial photovoltaic (PV) module systems. The method includes: acquiring the azimuth and elevation angles of a target; determining the tracking angle of the bifacial PV module system based on the target's azimuth and elevation angles; calculating the front and back irradiance of the bifacial PV module system at different tracking angles combined with different north-south spacing and support heights; obtaining the total irradiance of multiple bifacial PV module systems; and selecting the tracking angle, north-south spacing, and support height corresponding to the maximum total irradiance as the optimal target tracking result; acquiring the ambient temperature, diffuse reflection, dust levels, and dynamic shadows formed by the north-south spacing of the bifacial PV module system; and performing energy efficiency evaluation based on these factors to obtain the energy efficiency evaluation result of the bifacial PV module system. This invention can improve the accuracy of economic and technical feasibility studies.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a method for evaluating the energy efficiency of a photovoltaic system with a large-span flexible high support structure and bifacial modules. Background Technology

[0002] Current photovoltaic (PV) systems typically employ low-profile ground-mounted supports and single-sided PV modules. Their system energy efficiency assessment methods are relatively simple, failing to consider factors such as the back-side gain contribution of bifacial PV modules, the benefits of taller supports in reducing module temperature under wind speeds, maintaining cleanliness of the PV modules, and the reduction of shading due to larger north-south spacing. Therefore, the calculated system energy efficiency often deviates significantly from measured parameters, compromising the accuracy and rationality of economic and technical feasibility studies during the project development phase. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this invention is to provide an energy efficiency evaluation method for photovoltaic systems with large-span flexible high-support brackets and bifacial modules, which fully considers more practical factors and improves the accuracy and rationality of economic and technical feasibility studies.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] Energy efficiency assessment methods for long-span flexible high-support photovoltaic systems with bifacial modules include:

[0006] Obtain the azimuth and elevation angles of the target, and determine the tracking angle of the bifacial photovoltaic system based on the azimuth and elevation angles of the target.

[0007] By combining different tracking angles with different north-south spacing and bracket height, the front and back irradiance of the bifacial module photovoltaic system are calculated, the total irradiance of multiple bifacial module photovoltaic systems is obtained, and the tracking angle, north-south spacing and bracket height corresponding to the maximum total irradiance are taken as the best target tracking result.

[0008] The ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial photovoltaic system are obtained. Based on the ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial photovoltaic system, an energy efficiency assessment is performed, and the energy efficiency assessment result of the bifacial photovoltaic system is obtained.

[0009] Optionally, the formula for determining the tracking angle of the bifacial photovoltaic system is:

[0010]

[0011] Where θ is the reference tracking angle of the bifacial photovoltaic module, A is the solar altitude angle, and B is the solar azimuth angle.

[0012] Optionally, different tracking angles can be obtained in combination with different north-south spacing and bracket heights, including:

[0013] The target ranges for the tracking angle, the north-south spacing, and the bracket height are set respectively. Based on the target ranges, different tracking angles are obtained in combination with different north-south spacings and bracket heights.

[0014] Optionally, obtaining the ambient temperature of the bifacial photovoltaic system includes:

[0015] A sensing fiber optic cable is arranged around the ground surface surrounding the bifacial photovoltaic system to monitor the ground surface temperature around the bifacial photovoltaic system. A fiber optic temperature sensor array is fixedly installed on the back of the bifacial photovoltaic system to collect the ambient temperature on the back of the bifacial photovoltaic system.

[0016] Connect the fiber Bragg grating demodulator to the fiber Bragg grating temperature sensor array to collect the spatial temperature distribution data of the fiber Bragg grating temperature sensor array, and connect the distributed fiber optic temperature demodulator to the sensing fiber to collect the temperature distribution data of the sensing fiber.

[0017] The spatial temperature distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated to form the ambient temperature of the bifacial photovoltaic system.

[0018] Optionally, calibrating the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber includes:

[0019] The fiber Bragg grating temperature sensor array and the sensing fiber of a preset length are immersed in an ice-water compound to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber. The fiber Bragg grating temperature sensor array and the sensing fiber are then immersed in continuously boiling water to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber.

[0020] Based on the recorded temperature values, the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber are calculated respectively. Based on the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber, the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated.

[0021] Optionally, obtaining the energy efficiency assessment results of the bifacial photovoltaic system includes:

[0022] The diffuse reflection of the environment behind the bifacial photovoltaic system is analyzed to obtain the diffuse reflection irradiance. The dust level of the bifacial photovoltaic system is evaluated to obtain the pollution loss rate. The dynamic shadow formed by the north-south spacing is analyzed to obtain the shadow shading rate.

[0023] The ambient temperature, diffuse irradiance, pollution loss rate, and shading rate are input into the energy efficiency evaluation model to obtain the energy efficiency evaluation results of the bifacial photovoltaic system.

[0024] Optionally, the formula for obtaining the diffuse irradiance is:

[0025] H diffuse =f×ρ g ×(i d +i b )

[0026] Among them, H diffuse ρ is the diffuse irradiance, f is the visual factor, and ρ is the diffuse irradiance. g For ground reflectivity, i d i represents the solar diffuse irradiance on a horizontal surface. b This represents the amount of direct solar radiation on a horizontal surface.

[0027] Optionally, the formula for obtaining the soiling loss rate is:

[0028] C = 1 - η cleaned

[0029] Where C is the soil loss rate, η cleaned To account for component efficiency after contamination loss.

[0030] Optionally, the formula for obtaining the shadow occlusion rate is:

[0031]

[0032] Where D is the shadow occlusion rate, H i H represents the total irradiance. i,adjusted To take into account the adjustment of irradiance after shading.

[0033] Optionally, the formula for obtaining the energy efficiency assessment result of the bifacial photovoltaic system is:

[0034]

[0035] Among them, P actual For energy efficiency assessment results, P rated The rated power of the bifacial photovoltaic system under standard test conditions is given by α, where α is the temperature coefficient of the photovoltaic module, and T is the actual ambient temperature. STC The temperature under standard test conditions, Hdiffuse G represents diffuse irradiance. ref For reference irradiance, C is the soil loss rate, D is the shading rate, and H is the reference irradiance. i This represents the total irradiance.

[0036] The beneficial effects of this invention are as follows:

[0037] This invention calculates the front and back irradiance of a bifacial photovoltaic system by combining different tracking angles with different north-south spacing and support heights, obtains the total irradiance of multiple bifacial photovoltaic systems, and takes the tracking angle, north-south spacing and support height corresponding to the maximum total irradiance as the optimal target tracking result, thereby increasing power generation and improving the power generation efficiency of the entire system.

[0038] This invention uses ambient temperature, diffuse irradiance, pollution loss rate, and shading rate as inputs into the energy efficiency assessment model to obtain the energy efficiency assessment results of bifacial photovoltaic systems. It fully considers factors such as temperature, diffuse reflection on the back of the module, dust, and dynamic shading, providing a more accurate assessment method for system energy efficiency calculation. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. 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.

[0040] Figure 1 This is a flowchart of the energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to an embodiment of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] It should be noted that the following implementation methods are also applicable to energy efficiency assessment methods. The following text only uses the above methods as examples to illustrate energy efficiency assessment:

[0043] The system includes a power generation efficiency assessment module, a photovoltaic system temperature monitoring module, a photovoltaic system status monitoring module, a comprehensive analysis module, a performance classification module, and a response management module.

[0044] Power generation efficiency judgment module: Monitors and analyzes the real-time operating data of the photovoltaic system to determine whether the power generation of the photovoltaic system has reached the expected value. If the power generation of the photovoltaic system reaches the expected value, it calculates the actual power generation efficiency of the photovoltaic system based on the actual power generation and irradiance conditions, and judges whether the overall power generation efficiency of the photovoltaic system is abnormal by comparing it with the expected performance indicators. Photovoltaic system temperature monitoring module: When the overall power generation efficiency of the photovoltaic system is abnormal, it analyzes the temperature change rate of the inverter in the photovoltaic system based on the shade coverage area of ​​the photovoltaic system, judges the real-time fluctuation of the inverter temperature data, and evaluates the stability of the inverter temperature data. Photovoltaic system status ... status of the photovoltaic system is abnormal, it analyzes the temperature change rate of the inverter in the photovoltaic system based on the shade coverage area of ​​the photovoltaic system, judges the real-time fluctuation of the inverter temperature data, and evaluates the stability of the inverter temperature data. When the photovoltaic system's power generation efficiency is abnormal, the system analyzes the operating status of the photovoltaic panels based on different operating environments, determines the degree of aging of the photovoltaic panels, and assesses the interference with the photovoltaic panel's operating efficiency. The comprehensive analysis module integrates the stability of inverter temperature data and the interference with photovoltaic panel operating efficiency to assess whether the overall performance of the photovoltaic system is abnormal. The performance classification module classifies the photovoltaic system into normal and abnormal performance states based on the assessment results. The response management module analyzes the reduction in power generation under abnormal conditions, assesses its impact on power supply, and formulates corresponding management plans based on the assessment results when the photovoltaic system's performance is abnormal.

[0045] In the power generation efficiency judgment module, the real-time operating data of the photovoltaic system is monitored and analyzed to determine whether the power generation of the photovoltaic system has reached the expected value. If the power generation of the photovoltaic system reaches the expected value, the actual power generation efficiency of the photovoltaic system is calculated based on the actual power generation and sunlight conditions. By comparing it with the expected performance indicators, it is determined whether there is any abnormality in the overall power generation efficiency of the photovoltaic system. Specifically:

[0046] Use monitoring equipment or systems to collect real-time operational data from the photovoltaic system, including power generation, irradiance, temperature, voltage, and current. Record and organize the collected real-time operational data to ensure its completeness and accuracy. Recordings can be done every minute, hour, or day, depending on the needs.

[0047] Determine the method for calculating expected power generation. Expected power generation is typically calculated based on parameters such as solar irradiance, system capacity, and module rated power. The specific calculation formula can be: Expected Power Generation = Solar Irradiance × System Capacity × Module Efficiency; where solar irradiance is usually expressed in standard watts per square meter (W / m²). 2 The system capacity is expressed in kilowatts (kW), and the component efficiency is expressed as a percentage.

[0048] Determine the time period for which you want to calculate power generation; this can be per minute, per hour, per day, or other time intervals, as needed. Obtain power generation data for that time period from monitoring equipment or systems. This data is typically expressed in kilowatt-hours (kWh), representing the electrical energy generated during that period.

[0049] The acquired power generation data are summed to obtain the total power generation for that time period. If the data is power generation per minute or hour, it needs to be summed to obtain the total power generation. If the power generation data is expressed in other units, such as watt-hours (Wh), it needs to be converted to kilowatt-hours (kWh) for comparison with parameters such as system capacity.

[0050] The actual power generation is compared with the expected power generation. If the actual power generation is greater than or equal to the expected power generation, the system is performing well; otherwise, there may be a problem.

[0051] It should be noted that when comparing actual and expected power generation, the impact of environmental factors, such as weather, sunlight conditions, and temperature, needs to be considered. Sometimes, environmental factors may cause a discrepancy between actual and expected power generation.

[0052] Calculate the actual power generation efficiency of the photovoltaic system based on the actual power generation and sunlight conditions.

[0053] The calculated actual power generation efficiency is compared with the expected performance index. The expected performance index is the expected power generation efficiency of the photovoltaic system under ideal operating conditions. The specific value is set by those skilled in the art based on the specific power generation situation of the photovoltaic system, and will not be elaborated here.

[0054] If the actual power generation efficiency is greater than or equal to the expected performance index, it indicates that the overall power generation efficiency of the photovoltaic system is normal. Conversely, if the actual power generation efficiency is less than the expected performance index, it may indicate that the performance of the photovoltaic system is abnormal.

[0055] Photovoltaic system temperature monitoring module: When the overall power generation efficiency of the photovoltaic system is abnormal, the module analyzes the rate of temperature change of the inverter in the photovoltaic system based on the shade coverage area of ​​the photovoltaic system, judges the real-time fluctuation of the inverter temperature data, and evaluates the stability of the inverter temperature data.

[0056] Analyzing the rate of temperature change of the inverter in a photovoltaic system based on the shade coverage area means taking into account the potential shading within the system and further analyzing the inverter's temperature variations. Specifically, this means focusing on the rate of temperature change of the inverter, i.e., the degree of temperature change per unit time, which is affected by the shade coverage area.

[0057] Shading in a photovoltaic (PV) system affects sunlight reception, which in turn affects the heat generation of the PV modules. In the shaded areas, the PV modules receive less sunlight and generate less heat, which may cause the inverter temperature to change at a different rate than in the normal areas.

[0058] The temperature change rate data of the inverter in the shaded area of ​​the photovoltaic system is monitored and analyzed to determine the real-time fluctuation of the inverter temperature data. Based on the real-time monitored temperature change rate data, the temperature conversion rate fluctuation index of the inverter is obtained to evaluate the stability of the inverter temperature data. The method for obtaining the temperature conversion rate fluctuation index is as follows:

[0059] The size of the sliding window is determined based on the rate of temperature change of the inverter in the shaded area of ​​the photovoltaic system. If the data changes frequently, a smaller window size can be selected; if the data changes frequently, a larger window size can be selected.

[0060] For the temperature data within each sliding window, the temperature conversion rate is calculated. For each sliding window, based on the calculated temperature conversion rate, anomaly values ​​are calculated. The pre-set standard temperature range for the photovoltaic system inverter under normal conditions is obtained, and the calculated anomaly values ​​are compared with this range. The temperature conversion rate fluctuation index is calculated. When the calculated anomaly value is greater than the maximum temperature value of the photovoltaic system inverter under normal conditions, the obtained temperature conversion rate fluctuation index is compared with a reference threshold. If the temperature conversion rate fluctuation index is greater than or equal to the reference threshold, it indicates that the temperature data fluctuation in the inverter is more obvious and the stability of the inverter temperature data is lower. At this time, a temperature data anomaly signal is generated. If the temperature conversion rate fluctuation index is less than the reference threshold, it indicates that the temperature data fluctuation in the inverter is less obvious and the stability of the inverter temperature data is higher. At this time, a temperature data normal signal is generated.

[0061] The temperature slew rate fluctuation index reflects the degree of fluctuation in inverter temperature data, that is, the rate of temperature change. A large temperature slew rate fluctuation index indicates that the inverter temperature data fluctuates drastically over a certain period, with significant fluctuations in the rate of temperature change. This may be due to temperature instability caused by external environmental factors, system faults, or other factors. Therefore, the larger the temperature slew rate fluctuation index, the worse the stability of the inverter temperature data and the more unstable the system's operating state.

[0062] Photovoltaic system status monitoring module: When the overall power generation efficiency of the photovoltaic system is abnormal, the module analyzes the working status of the photovoltaic panels in the photovoltaic system according to different working environments, judges the performance aging degree of the photovoltaic panels, and assesses the interference of the photovoltaic panels' working efficiency.

[0063] Electrical performance tests are performed on the components of the photovoltaic (PV) panel. The characteristic data of performance degradation are analyzed to obtain the performance degradation sensitivity index, assessing the interference with the PV panel's efficiency. The initial performance degradation value at time t=1 is used as the first initial value. For each time t>1, the performance degradation value at each time is compared with the initial value. The performance degradation sensitivity index is calculated using exponential smoothing. The obtained performance degradation sensitivity index is compared with a reference threshold. If the performance degradation sensitivity index is greater than or equal to the reference threshold, it indicates a more severe aging of the PV panel and a more significant interference with its efficiency, generating an abnormal performance signal. If the performance degradation sensitivity index is less than the reference threshold, it indicates a milder aging of the PV panel and a less significant interference with its efficiency, generating a normal performance signal.

[0064] A higher performance degradation sensitivity index indicates a faster rate of performance degradation for the photovoltaic panel, meaning a greater decrease in the panel's efficiency. Therefore, it suggests that the photovoltaic panel's efficiency is more susceptible to interference.

[0065] In other words, when the performance degradation sensitivity index is high, the performance of the solar panel is unstable and may be affected by various factors, such as module aging, shading, and temperature changes, leading to a decrease in the efficiency of the photovoltaic panel. Therefore, the performance degradation sensitivity index can be used as an indicator to assess the interference with the efficiency of photovoltaic panels; the higher the index, the more significant the interference.

[0066] Comprehensive Analysis Module: This module performs a comprehensive analysis of the stability of inverter temperature data and the interference of photovoltaic panel operating efficiency to assess whether there are any abnormalities in the overall performance of the photovoltaic system.

[0067] The temperature conversion rate fluctuation index and the performance degradation sensitivity index are normalized, and the anomaly assessment coefficient of the overall performance of the photovoltaic system is calculated using the normalized temperature conversion rate fluctuation index and the performance degradation sensitivity index.

[0068] Performance Classification Module: Based on the evaluation results, the photovoltaic system is classified into two states: normal performance and abnormal performance.

[0069] The obtained anomaly assessment coefficient of the overall performance of the photovoltaic system is compared with the reference threshold for anomaly assessment coefficient. If the anomaly assessment coefficient of the overall performance of the photovoltaic system is greater than or equal to the reference threshold, it indicates that the overall performance of the photovoltaic system is more likely to be abnormal. The photovoltaic system is classified as having an abnormal performance state, and an abnormal photovoltaic system status signal is generated. At this time, the performance of the photovoltaic system needs to be adjusted immediately, and the system operating parameters should be optimized to improve the overall performance of the system. If the anomaly assessment coefficient of the overall performance of the photovoltaic system is less than the reference threshold, it indicates that the overall performance of the photovoltaic system is less likely to be abnormal. The photovoltaic system is classified as having a normal performance state, and a normal photovoltaic system signal is generated. At this time, the system performance needs to be continuously monitored to promptly identify and resolve potential problems and ensure the long-term stable operation of the system.

[0070] In this embodiment, the photovoltaic system's operating data, including power generation and sunlight conditions, is monitored in real time to determine whether the system's power generation has reached the expected value. If the power generation reaches the expected value, the system calculates the actual power generation efficiency of the photovoltaic system and compares it with the expected performance indicators to determine whether the overall power generation efficiency of the photovoltaic system is normal.

[0071] If the power generation efficiency is abnormal, the system will further analyze the temperature change rate of the inverter in the photovoltaic system and assess the stability of the inverter temperature data. Simultaneously, based on the photovoltaic system's operating environment, the system will analyze the operating status of the photovoltaic panels, determine their performance aging degree, and assess the interference with the photovoltaic panel's operating efficiency. By comprehensively analyzing the stability of the inverter temperature data and the interference with the photovoltaic panel's operating efficiency, the system assesses whether the overall performance of the photovoltaic system is abnormal and classifies it as normal or abnormal. This system can promptly detect and diagnose abnormalities in the photovoltaic system, providing effective decision support for operation and maintenance personnel and ensuring the stable operation of the photovoltaic system.

[0072] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] like Figure 1As shown in the figure, this embodiment discloses an energy efficiency evaluation method for a long-span flexible high-support and bifacial module photovoltaic system, including: obtaining the azimuth and elevation angles of the target; determining the tracking angle of the bifacial module photovoltaic system based on the azimuth and elevation angles of the target; calculating the front and back irradiance of the bifacial module photovoltaic system at different tracking angles combined with different north-south spacing and support height; obtaining the total irradiance of multiple bifacial module photovoltaic systems; and taking the tracking angle, north-south spacing, and support height corresponding to the maximum total irradiance as the optimal target tracking result; obtaining the ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial module photovoltaic system; and performing an energy efficiency evaluation based on the ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial module photovoltaic system to obtain the energy efficiency evaluation result of the bifacial module photovoltaic system.

[0074] Specifically:

[0075] This embodiment discloses a method for evaluating the energy efficiency of a long-span flexible high-support photovoltaic system with bifacial modules, including:

[0076] Step 1: Set the optimal tilt angle, north-south spacing, and support height based on local latitude and lighting conditions;

[0077] Step 2: Establish an ideal model for system energy efficiency analysis;

[0078] Step 3: Perform temperature field analysis to obtain the accurate range of ambient temperature for photovoltaic modules;

[0079] Step 4: Analyze the diffuse reflection of the surrounding environment on the back of the component and calculate the diffuse irradiance;

[0080] Step 5: Assess the level of dust on site and calculate the contamination loss rate on the front of the components;

[0081] Step 6: Analyze the dynamic shadows formed by the north-south distance and calculate the shadow occlusion rate;

[0082] Step 7: Introduce the disturbance factors calculated in steps 3, 4, 5, and 6 into the ideal model for system energy efficiency analysis, and recalculate the system energy efficiency.

[0083] Positioning and Tracking: First, determine the azimuth and altitude of the target (i.e., the sun), and adjust the tracking direction of the photovoltaic system based on this data. Calculate the total radiation on both the front and back sides of the photovoltaic system based on different tracking angles, combined with varying north-south spacing and support height. By comparing the total radiation under different configurations, identify the tracking angle, north-south spacing, and support height that generate the maximum radiation, as the optimal tracking configuration.

[0084] Energy efficiency assessment: Environmental factors are considered, including temperature, ground reflectivity, dust levels, and shading effects caused by module spacing. Based on these environmental parameters, an energy efficiency analysis is performed on the bifacial photovoltaic system to assess its performance. The final energy efficiency assessment results of the photovoltaic system are then derived to guide system design and optimization.

[0085] In short, this process involves precise solar tracking of the photovoltaic system and a comprehensive evaluation of the system's performance, taking into account various environmental factors. These steps determine the optimal system configuration and assess its energy efficiency.

[0086] Furthermore, the formula for determining the tracking angle of a bifacial photovoltaic system is:

[0087]

[0088] Where θ is the reference tracking angle of the bifacial photovoltaic module, A is the solar altitude angle, and B is the solar azimuth angle.

[0089] Furthermore, obtaining different tracking angles combined with different north-south spacing and bracket heights includes:

[0090] Set the target range for tracking angle, north-south spacing, and bracket height respectively. Based on the target range, obtain different tracking angles combined with different north-south spacing and bracket heights.

[0091] Furthermore, obtaining the ambient temperature of the bifacial photovoltaic system includes:

[0092] Sensing optical fibers are arranged around the ground surface surrounding the bifacial photovoltaic system to monitor the ground surface temperature around the bifacial photovoltaic system. A fiber optic temperature sensor array is fixedly installed on the back of the bifacial photovoltaic system to collect the ambient temperature on the back of the bifacial photovoltaic system.

[0093] Connect the fiber Bragg grating demodulator to the fiber Bragg grating temperature sensor array to collect the spatial temperature distribution data of the fiber Bragg grating temperature sensor array, and connect the distributed fiber optic temperature demodulator to the sensing fiber to collect the temperature distribution data of the sensing fiber.

[0094] The spatial temperature distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated to form the ambient temperature of the bifacial photovoltaic system.

[0095] Specifically:

[0096] Surface temperature monitoring: The surface temperature is monitored in real time by deploying sensing optical fibers around the photovoltaic system.

[0097] Back-side ambient temperature acquisition: A fiber optic temperature sensor array is installed on the back of the photovoltaic system to collect ambient temperature data.

[0098] Temperature data acquisition and demodulation: A fiber Bragg grating demodulator is connected to the sensor array to collect spatial temperature distribution data from the sensor array. Simultaneously, a distributed fiber optic temperature demodulator is connected to the sensing fiber to acquire temperature distribution data from the sensing fiber.

[0099] Data calibration and integration: Temperature data collected by the sensor array and sensing fiber optics are calibrated to ensure accuracy. The calibrated data is then integrated to create a comprehensive view of the photovoltaic system's ambient temperature.

[0100] In short, this process involves using fiber optic sensors to monitor the temperature of the ground surface and the area behind the photovoltaic system, collecting and calibrating this data using a demodulator, and ultimately generating an accurate description of the photovoltaic system's ambient temperature. Such a monitoring system helps to more accurately understand and optimize the performance of photovoltaic systems under different environmental conditions.

[0101] Furthermore, the calibration of the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber includes:

[0102] The fiber Bragg grating temperature sensor array and the sensing fiber of a preset length were immersed in an ice-water compound to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber. The fiber Bragg grating temperature sensor array and the sensing fiber were then immersed in continuously boiling water to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber.

[0103] Based on the recorded temperature values, the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber are calculated respectively. Based on the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber, the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated.

[0104] Specifically:

[0105] Surface temperature monitoring: The surface temperature is monitored in real time by deploying sensing optical fibers around the photovoltaic system.

[0106] Back-side ambient temperature acquisition: A fiber optic temperature sensor array is installed on the back of the photovoltaic system to collect ambient temperature data.

[0107] Temperature data acquisition and demodulation: A fiber Bragg grating demodulator is connected to the sensor array to collect spatial temperature distribution data from the sensor array. Simultaneously, a distributed fiber optic temperature demodulator is connected to the sensing fiber to acquire temperature distribution data from the sensing fiber.

[0108] Data calibration and integration: Temperature data collected by the sensor array and sensing fiber optics are calibrated to ensure accuracy. The calibrated data is then integrated to create a comprehensive view of the photovoltaic system's ambient temperature.

[0109] In short, this process involves using fiber optic sensors to monitor the temperature of the ground surface and the area behind the photovoltaic system, collecting and calibrating this data using a demodulator, and ultimately generating an accurate description of the photovoltaic system's ambient temperature. Such a monitoring system helps to more accurately understand and optimize the performance of photovoltaic systems under different environmental conditions.

[0110] Furthermore, obtaining the energy efficiency assessment results of the bifacial photovoltaic system includes:

[0111] The diffuse reflection of the environment behind the bifacial photovoltaic system is analyzed to obtain the diffuse reflection irradiance. The dust level of the bifacial photovoltaic system is assessed to obtain the pollution loss rate. The dynamic shadow formed by the north-south spacing is analyzed to obtain the shadow shading rate.

[0112] By inputting ambient temperature, diffuse irradiance, pollution loss rate, and shading rate into the energy efficiency assessment model, the energy efficiency assessment results of the bifacial photovoltaic system are obtained.

[0113] Furthermore, the formula for obtaining diffuse reflectance irradiance is:

[0114] H diffuse =f×ρ g ×(i d +i b )

[0115] Among them, H diffuse ρ is the diffuse irradiance, f is the visual factor, and ρ is the diffuse irradiance. g For ground reflectivity, i d i represents the solar diffuse irradiance on a horizontal surface. b This represents the amount of direct solar radiation on a horizontal surface.

[0116] Furthermore, the formula for obtaining the soiling loss rate is:

[0117] C = 1 - η cleaned

[0118] Where C is the soil loss rate, η cleaned To account for component efficiency after contamination loss.

[0119] Furthermore, the formula for obtaining the shadow occlusion rate is:

[0120]

[0121] Where D is the shadow occlusion rate, Hi H represents the total irradiance. i,adjusted To take into account the adjustment of irradiance after shading.

[0122] Furthermore, the formula for obtaining the energy efficiency assessment results of a bifacial photovoltaic system is as follows:

[0123]

[0124] Among them, P actual For energy efficiency assessment results, P rated The rated power of the bifacial photovoltaic system under standard test conditions is given by α, where α is the temperature coefficient of the photovoltaic module, and T is the actual ambient temperature. STC The temperature under standard test conditions, H diffuse G represents diffuse irradiance. ref For reference irradiance, C is the soil loss rate, D is the shading rate, and H is the reference irradiance. i This represents the total irradiance.

[0125] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for evaluating the energy efficiency of a photovoltaic system with a long-span flexible high support structure and bifacial modules, characterized in that... include: Obtain the azimuth and elevation angles of the target, and determine the tracking angle of the bifacial photovoltaic system based on the azimuth and elevation angles of the target. The formula for determining the tracking angle of the bifacial photovoltaic system is: in, This serves as the reference tracking angle for bifacial photovoltaic modules. The solar altitude angle, The azimuth of the sun; By combining different tracking angles with different north-south spacing and bracket height, the front and back irradiance of the bifacial module photovoltaic system are calculated, the total irradiance of multiple bifacial module photovoltaic systems is obtained, and the tracking angle, north-south spacing and bracket height corresponding to the maximum total irradiance are taken as the best target tracking result. Obtaining different tracking angles combined with different north-south spacing and bracket heights includes: Set the target ranges for the tracking angle, the north-south spacing, and the bracket height respectively. Based on the target ranges, obtain different tracking angles combined with different north-south spacings and bracket heights. The ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial photovoltaic system are obtained. Based on the ambient temperature, ambient diffuse reflection, dust level, and dynamic shadow formed by the north-south spacing of the bifacial photovoltaic system, an energy efficiency assessment is performed, and the energy efficiency assessment result of the bifacial photovoltaic system is obtained. Obtaining the ambient temperature of the bifacial photovoltaic system includes: A sensing fiber optic cable is arranged around the ground surface surrounding the bifacial photovoltaic system to monitor the ground surface temperature around the bifacial photovoltaic system. A fiber optic temperature sensor array is fixedly installed on the back of the bifacial photovoltaic system to collect the ambient temperature on the back of the bifacial photovoltaic system. Connect the fiber Bragg grating demodulator to the fiber Bragg grating temperature sensor array to collect the spatial temperature distribution data of the fiber Bragg grating temperature sensor array, and connect the distributed fiber optic temperature demodulator to the sensing fiber to collect the temperature distribution data of the sensing fiber. The spatial temperature distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated to form the ambient temperature of the bifacial photovoltaic system.

2. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 1, characterized in that, The calibration of the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber includes: The fiber Bragg grating temperature sensor array and the sensing fiber of a preset length are immersed in an ice-water compound to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber. The fiber Bragg grating temperature sensor array and the sensing fiber are then immersed in continuously boiling water to obtain the temperature values ​​recorded by the fiber Bragg grating temperature sensor array and the sensing fiber. Based on the recorded temperature values, the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber are calculated respectively. Based on the sensitivity coefficients of the fiber Bragg grating temperature sensor array and the sensing fiber, the temperature spatial distribution data of the fiber Bragg grating temperature sensor array and the temperature distribution data of the sensing fiber are calibrated.

3. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 1, characterized in that, Obtaining the energy efficiency assessment results of the bifacial photovoltaic system includes: The diffuse reflection of the environment behind the bifacial photovoltaic system is analyzed to obtain the diffuse reflection irradiance. The dust level of the bifacial photovoltaic system is evaluated to obtain the pollution loss rate. The dynamic shadow formed by the north-south spacing is analyzed to obtain the shadow shading rate. The ambient temperature, diffuse irradiance, pollution loss rate, and shading rate are input into the energy efficiency evaluation model to obtain the energy efficiency evaluation results of the bifacial photovoltaic system.

4. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 3, characterized in that, The formula for obtaining the diffuse irradiance is: in, This refers to diffuse irradiance. As a visual factor, For ground reflectivity, This represents the amount of solar diffuse irradiance on a horizontal surface. This represents the amount of direct solar radiation on a horizontal surface.

5. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 3, characterized in that, The formula for obtaining the soiling loss rate is: in, For soil loss rate, To account for component efficiency after contamination loss.

6. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 3, characterized in that, The formula for obtaining the shadow occlusion rate is: in, For shadow occlusion rate, Total irradiance To take into account the adjustment of irradiance after shading.

7. The energy efficiency evaluation method for a large-span flexible high-support and bifacial module photovoltaic system according to claim 3, characterized in that, The formula for obtaining the energy efficiency assessment result of the bifacial photovoltaic system is as follows: in, For energy efficiency assessment results, This represents the rated power of a bifacial photovoltaic system under standard test conditions. The temperature coefficient of a photovoltaic module. This refers to the actual ambient temperature. Temperature under standard test conditions. This refers to diffuse irradiance. For reference irradiance, For soil loss rate, For shadow occlusion rate, This represents the total irradiance.

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