Photovoltaic panel light transmittance measuring method based on photovoltaic output current

Abstract

The invention provides a photovoltaic panel light transmittance measuring method based on photovoltaic output current. The photovoltaic panel light transmittance measuring method comprises the following steps that S1, the output current, the working temperature and the irradiance of a photovoltaic panel to be measured are detected; s2, determining the output current of the to-be-tested photovoltaic panel which is not covered with the light-transmitting material under the standard test condition; s3, correcting the output current of the photovoltaic panel to be tested in the outdoor test environment to obtain the corrected output current of the photovoltaic panel; and S4, determining the light transmittance of the photovoltaic panel based on the corrected output current of the photovoltaic panel and the output current under the standard test condition. According to the method, the light transmittance of the optical thin film of the photovoltaic panel is determined through the output current of the photovoltaic panel to be tested in an actual environment, the testing process does not need to be separated from an actual spectral environment, accurate data support is provided for subsequent performance analysis and fault analysis of the photovoltaic panel, laboratory inspection is not needed, and the testing efficiency is improved. Therefore, the test efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a photovoltaic panel light transmittance measurement method, in particular to a photovoltaic panel light transmittance measurement method based on photovoltaic output current. BACKGROUND

[0002] Optical film is generally provided in the photovoltaic panel to reduce optical fiber reflection and improve the light absorption efficiency of the photovoltaic panel, but the power generation efficiency of the photovoltaic panel is affected by the light transmittance of the optical film, so it is necessary to accurately determine the light transmittance of the optical film for subsequent power generation analysis of the photovoltaic panel.

[0003] In the prior art, the determination of the light transmittance of the photovoltaic panel mainly depends on the laboratory spectrophotometer, and the average transmittance in the visible light band is calculated through spectral analysis, but this method has the following defects: first, the optical film needs to be cut and inspected, but for the photovoltaic panel that has been put into use, it is impossible to measure in situ; second, due to the need for inspection process, it is difficult to meet the on-site working condition requirements of the photovoltaic panel, and the photovoltaic panel needs to be quickly inspected on site; third, the laboratory environment cannot reproduce the actual spectral conditions, such as the angle of sunlight and atmospheric attenuation, which leads to the deviation between the laboratory measurement results and the actual application.

[0004] Therefore, in order to solve the above technical problems, it is necessary to propose a new technical means. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a photovoltaic panel light transmittance measurement method based on photovoltaic output current, which determines the light transmittance of the optical film of the photovoltaic panel through the output current of the photovoltaic panel to be measured in the actual environment, thereby providing accurate data support for subsequent performance analysis and fault analysis of the photovoltaic panel, and without the need for laboratory inspection, thereby improving the test efficiency.

[0006] The present application provides a photovoltaic panel light transmittance measurement method based on photovoltaic output current, comprising the following steps:

[0007] S1. Detecting the output current, working temperature and irradiance of the photovoltaic panel to be measured;

[0008] S2. Determining the output current of the photovoltaic panel to be measured without covering the light transmittance material under standard test conditions;

[0009] S3. Correcting the output current of the photovoltaic panel to be measured in the outdoor test environment to obtain the corrected output current of the photovoltaic panel;

[0010] S4. Determining the light transmittance of the photovoltaic panel based on the corrected output current of the photovoltaic panel and the output current under standard test conditions.

[0011] Furthermore, the output current of the photovoltaic panel to be tested in an outdoor test environment is calibrated by the following method:

[0012]

[0013] Among them: I 修正 is the corrected photovoltaic panel output current, S 测 Indicates the measured irradiance in the outdoor test environment, S 标准 Indicates the irradiance under standard test conditions, T 测 is the measured operating temperature of the photovoltaic panel in the outdoor test environment, T 标准 is the operating temperature of the photovoltaic panel under test under standard test conditions, a is the current temperature coefficient of the photovoltaic panel under test, I 测 is the actual current value of the photovoltaic panel under test in an off-site test environment.

[0014] Furthermore, in step S5, the light transmittance of the photovoltaic panel to be tested is determined by the following method:

[0015] τ=(I 修正 / I 标准 )*k;

[0016] Among them, I 标准 It represents the output current of the photovoltaic panel under test without covering light-transmitting material under standard test conditions; k is the error correction coefficient.

[0017] Furthermore, in step S2, the output current, operating temperature and irradiance of the photovoltaic panel to be tested are synchronously collected.

[0018] Furthermore, in step S2, a standard solar cell or thermopile sensor is used to detect the irradiance of the photovoltaic panel.

[0019] The beneficial effects of the present invention are as follows: Through the present invention, the transmittance of the optical film of the photovoltaic panel can be determined by the output current of the photovoltaic panel to be tested in an actual environment, without making the testing process separate from the actual spectral environment, thereby providing accurate data support for subsequent performance analysis and fault analysis of the photovoltaic panel. Moreover, there is no need to send the panel to the laboratory for inspection, thereby improving the testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below:

[0023] The present invention provides a method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current, comprising the following steps:

[0024] S1. detecting output current, working temperature and irradiance of the to-be-tested photovoltaic panel;

[0025] S2. determining output current of the to-be-tested photovoltaic panel without the covering light-transmitting material under standard test conditions;

[0026] S3. correcting output current of the to-be-tested photovoltaic panel in the outdoor test environment to obtain corrected output current of the photovoltaic panel;

[0027] S4. determining light transmittance of the photovoltaic panel based on the corrected output current of the photovoltaic panel and the output current under the standard test conditions. Through the above method, the light transmittance of the optical film of the photovoltaic panel is determined through the output current of the to-be-tested photovoltaic panel in the actual environment, without making the test process deviate from the actual spectral environment, thereby providing accurate data support for subsequent performance analysis and fault analysis of the photovoltaic panel, and without laboratory inspection, thereby improving test efficiency.

[0028] wherein the standard test conditions refer to STC: irradiance 1000 W / m 2 , cell temperature 25℃, AM1.5 spectrum, which can be completed by building a corresponding test box on site, for example, the test box is made of light-transmitting material, the light transmittance of which can be determined in advance, so that the irradiance of the photovoltaic panel meets the requirements of the standard test conditions, and the temperature of the test box can be determined by existing methods, such as setting a temperature adjusting device (such as an air conditioner, etc.) in the test box, so that the working temperature of the photovoltaic panel is 25℃.

[0029] In this embodiment, the output current of the to-be-tested photovoltaic panel in the outdoor test environment is corrected by the following method:

[0030]

[0031] wherein: I 修正 is the corrected output current of the photovoltaic panel, S 测 represents the measured irradiance in the outdoor test environment, S 标准 represents the irradiance under the standard test conditions, T 测 is the measured working temperature of the photovoltaic panel in the outdoor test environment, T 标准 is the working temperature of the to-be-tested photovoltaic panel under the standard test conditions, a is the current temperature coefficient of the to-be-tested photovoltaic panel, I 测 is the measured current value of the to-be-tested photovoltaic panel in the outdoor test environment. Through the correction process, the influence of environmental fluctuations can be eliminated, and the accuracy of the final result is ensured.

[0032] wherein the light transmittance of the to-be-tested photovoltaic panel is determined by the following method in step S5:

[0033] τ = (I 修正 / I 标准 )*k;

[0034] Wherein, I 标准 represents the output current of the photovoltaic panel to be measured under standard test conditions without covering the light-transmitting material; k is the error correction coefficient. Through the above method, the light transmittance of the optical film of the photovoltaic panel can be accurately determined without other complex testing processes, and the accuracy can be guaranteed.

[0035] In the embodiment, in step S2, the output current, working temperature and irradiance of the photovoltaic panel to be measured are synchronously collected, that is, the detection of each output current, working dimension and irradiance in the actual environment must be one-to-one corresponding, so as to ensure the accuracy of the final result.

[0036] For the detection of irradiance, a high-precision, fast-response solar irradiance sensor (such as a standard solar cell or a thermoelectric pile sensor) conforming to the ISO 9060 standard (level two or above) is used, and a temperature sensor (such as PT100 or a thermistor) attached to the back plate or built-in the photovoltaic module is used for temperature detection, so as to accurately obtain the working temperature of the photovoltaic cell. Temperature is a key parameter for determining the open-circuit voltage, fill factor and efficiency of the cell: the change of the temperature will cause the output current characteristic curve to be significantly offset.

[0037] For the current collection of the photovoltaic panel: the output current change of the photovoltaic module near the actual working point is collected at high speed through the existing data acquisition unit (DAU). This can be achieved in the following ways: (1) a small range of fast voltage scanning or pulse is applied; (2) during the operation of the high-precision maximum power point tracking (MPPT) algorithm, the current (I) and voltage (V) data of the working point are extracted in real time. The core goal is to obtain the data reflecting the key part of the instantaneous I-V characteristic curve of the module under the current irradiance and temperature, especially the current near the maximum power point Imp.

[0038] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and all of them should be covered in the scope of the claims of the present application.

Claims

1. A method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current, characterized in that: The following steps are involved: S1. Detect the output current, operating temperature and irradiance of the photovoltaic panel under test; S2. Determine the output current of the photovoltaic panel under test without covering light-transmitting material under standard test conditions; S3. The output current of the photovoltaic panel to be tested is corrected in an outdoor test environment to obtain a corrected output current of the photovoltaic panel; S4. Determine the light transmittance of the photovoltaic panel based on the calibrated output current of the photovoltaic panel and the output current under standard test conditions.

2. The method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current according to claim 1, characterized in that: The output current of the photovoltaic panel to be tested in an outdoor test environment is calibrated by the following method: Where: I 修正 is the corrected photovoltaic panel output current, S 测 Indicates the measured irradiance in the outdoor test environment, S 标准 Indicates the irradiance under standard test conditions, T 测 is the measured operating temperature of the photovoltaic panel in the outdoor test environment, T 标准 is the operating temperature of the photovoltaic panel under test under standard test conditions, a is the current temperature coefficient of the photovoltaic panel under test, I 测 is the actual current value of the photovoltaic panel under test in an off-site test environment.

3. The method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current according to claim 2, wherein: In step S5, the light transmittance of the photovoltaic panel to be tested is determined by the following method: τ=(I 修正 / I 标准 )*k; Among them, I 标准 It represents the output current of the photovoltaic panel under test without covering light-transmitting material under standard test conditions; k is the error correction coefficient.

4. The method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current according to claim 1, wherein: Step S2: synchronously collecting the output current, operating temperature, and irradiance of the photovoltaic panel to be tested.

5. The method for measuring the transmittance of a photovoltaic panel based on photovoltaic output current according to claim 1, wherein: In step S2, a standard solar cell or thermopile sensor is used to detect the irradiance of the photovoltaic panel.

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