Photovoltaic panel cleaning state determination method based on output characteristics of photovoltaic panel

Abstract

The invention provides a photovoltaic panel cleaning state determination method based on output characteristics of a photovoltaic panel. The photovoltaic panel cleaning state determination method comprises the following steps: S1, arranging at least three irradiance sensors on a tested photovoltaic panel; s2, acquiring an irradiance value output by the irradiance sensor, and acquiring an output current and a working temperature of the photovoltaic panel to be detected at the same time; s3, determining the light transmittance of the tested photovoltaic panel based on the irradiance, the output current and the working temperature; and S4, the maximum irradiance value of the position where the detected photovoltaic panel is located is obtained, the cleaning state of the photovoltaic panel is determined based on the historical irradiance value and the light transmittance of the detected photovoltaic panel, through the method, the light transmittance factor is determined through the actually measured photovoltaic panel parameters, including the irradiance, the temperature and the output current, and the cleaning state of the photovoltaic panel is determined. Therefore, the influence of environmental factors is fully considered, the to-be-cleaned state of the photovoltaic panel can be effectively determined, the hot spot effect caused by dust accumulation is effectively avoided, and the manpower and cleaning resource cost can be effectively reduced.

Description

Technical Field

[0001] This invention relates to a method for determining the cleaning status of a photovoltaic panel, and more particularly to a method for determining the cleaning status of a photovoltaic panel based on the output characteristics of the photovoltaic panel. Background Technology

[0002] Dust accumulation on the surface of photovoltaic panels leads to a decrease in light transmittance, which is one of the main factors causing power generation loss. Therefore, it is necessary to clean and maintain photovoltaic panels.

[0003] In existing technologies, the cleaning status of photovoltaic panels is mainly determined by periodic cleaning or manual visual inspection. Periodic cleaning is easily affected by seasonal climate, resulting in waste of water and manpower during low-pollution periods, while during high-pollution periods, the failure to clean in a timely manner leads to continuous loss of power generation. More seriously, severe dust accumulation can cause hot spot effects, accelerating the aging of photovoltaic panels and even causing permanent damage. Manual judgment lacks quantitative basis and makes it difficult to accurately assess the actual impact of dirt on power generation efficiency.

[0004] While current technologies assess the cleaning status of photovoltaic (PV) panels by monitoring the decrease in their power generation, they fail to effectively differentiate the coupled effects of environmental variables such as irradiance and temperature with pollution factors. For example, the same level of pollution exhibits significantly different power losses under different irradiance conditions, and temperature changes also alter the current output characteristics of the solar cells. Decisions based solely on power output reduction without eliminating environmental variables can lead to misjudgments—potentially underestimating pollution losses during periods of low irradiance or overestimating pollution risks during periods of high temperatures.

[0005] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Summary of the Invention

[0006] This invention provides a method for determining the cleaning status of photovoltaic panels based on their output characteristics. By using measured photovoltaic panel parameters, including irradiance, temperature, and output current, the transmittance factor is determined, thus fully considering the influence of environmental factors. This method can effectively determine the cleaning status of the photovoltaic panel, effectively avoid the hot spot effect caused by dust accumulation, and effectively reduce labor and cleaning resource costs.

[0007] This invention provides a method for determining the cleaning status of a photovoltaic panel based on its output characteristics, comprising the following steps:

[0008] S1. Arrange at least 3 irradiance sensors on the photovoltaic panel under test;

[0009] S2. Obtain the irradiance value output by the irradiance sensor and simultaneously obtain the output current and operating temperature of the photovoltaic panel under test;

[0010] S3. Determine the transmittance of the photovoltaic panel under test based on irradiance, output current, and operating temperature;

[0011] S4. Obtain the maximum irradiance value at the location of the photovoltaic panel under test, and determine the cleaning status of the photovoltaic panel based on the historical irradiance value and the transmittance of the photovoltaic panel under test.

[0012] Furthermore, step S4 specifically includes:

[0013] The maximum irradiance value is selected from the irradiance values ​​at the location of the photovoltaic panel;

[0014] When the maximum irradiance value S is greater than or equal to 1000 W / m 2 If the light transmittance τ of the photovoltaic panel is less than 95%, the photovoltaic panel under test is deemed to need cleaning.

[0015] When the maximum irradiance value is 800W / m 2 <S<1000W / m 2 If the light transmittance τ of the photovoltaic panel is less than 90%, the photovoltaic panel under test is determined to need cleaning.

[0016] When the maximum irradiance value S≤800W / m 2 If the light transmittance τ of the photovoltaic panel is less than 85%, the photovoltaic panel under test is determined to need cleaning.

[0017] Furthermore, the light transmittance τ of the photovoltaic panel is determined using the following method:

[0018]

[0019] Among them: I 测 I represents the measured current output value of the photovoltaic panel under test. 标准 S represents the current output value of the photovoltaic panel under test under standard conditions. 标准 S represents the irradiance under standard conditions. 测 The measured current output value of the photovoltaic panel under test is represented by T, the measured operating temperature of the photovoltaic panel under test is represented by a, and the current temperature coefficient of the photovoltaic panel under test is represented by a.

[0020] Furthermore, the measured current output value S of the photovoltaic panel under test is determined using the following method. 测 :

[0021]

[0022] Wherein: S i d represents the irradiance value output by the i-th irradiance sensor. i This represents the distance between the i-th irradiance sensor probe and the photovoltaic panel.

[0023] The beneficial effects of this invention are as follows: By using the measured parameters of the photovoltaic panel, including irradiance, temperature and output current, the transmittance factor can be determined. This fully considers the influence of environmental factors, thereby effectively determining the state of the photovoltaic panel to be cleaned, effectively avoiding the hot spot effect caused by dust accumulation, and effectively reducing manpower and cleaning resource costs. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below:

[0027] This invention provides a method for determining the cleaning status of a photovoltaic panel based on its output characteristics, comprising the following steps:

[0028] S1. Arrange at least 3 irradiance sensors on the photovoltaic panel under test;

[0029] S2. Obtain the irradiance value output by the irradiance sensor and simultaneously obtain the output current and operating temperature of the photovoltaic panel under test;

[0030] S3. Determine the transmittance of the photovoltaic panel under test based on irradiance, output current, and operating temperature;

[0031] S4. Obtain the maximum irradiance value at the location of the photovoltaic panel under test, and determine the cleaning status of the photovoltaic panel based on the historical irradiance value and the transmittance of the photovoltaic panel under test. Through the above method, the transmittance factor is determined by the measured photovoltaic panel parameters, including irradiance, temperature and output current, so as to fully consider the influence of environmental factors, thereby effectively determining the cleaning status of the photovoltaic panel, effectively avoiding the hot spot effect caused by dust accumulation, and effectively reducing manpower and cleaning resource costs.

[0032] In this embodiment, step S4 specifically includes:

[0033] The maximum irradiance value is selected from the irradiance values ​​at the location of the photovoltaic panel. When monitoring the irradiance of the photovoltaic panel, the temperature, output current, and irradiance are collected at the same time and in a continuous process. For example, if a time limit of 3 days is used, each day is divided into several time points, then there are n irradiance values. The operating temperature and output current are also n. In one day, n transmittance values ​​can be obtained. Then, in 3 days, 3n transmittance values ​​can be obtained. The transmittance corresponding to the time with the maximum irradiance value is selected as the judgment criterion.

[0034] For irradiance detection, high-precision, fast-response solar irradiance sensors (such as standard solar cell or thermopile sensors) conforming to ISO 9060 standards (Level 2 or above) are used. Temperature detection employs temperature sensors (such as PT100 or thermistors) attached to or built into the photovoltaic module backsheet to accurately obtain the operating temperature of the photovoltaic cells. Temperature is a key parameter determining the cell's open-circuit voltage, fill factor, and efficiency; its changes can cause significant shifts in the output current characteristic curve.

[0035] For photovoltaic (PV) panel current acquisition: High-speed acquisition of the output current variation of the PV module near the actual operating point is achieved using existing data acquisition units (DAUs). This can be achieved by: (1) applying a small-range rapid voltage scan or pulse; and (2) extracting the current (I) and voltage (V) data of the operating point in real time during the operation of a high-precision maximum power point tracking (MPPT) algorithm. The core objective is to acquire data on the key portion of the instantaneous IV characteristic curve of the module (with particular focus on the current Imp near the maximum power point) that reflects the current irradiance and temperature.

[0036] When the maximum irradiance value S is greater than or equal to 1000 W / m 2 If the light transmittance τ of the photovoltaic panel is less than 95%, the photovoltaic panel under test is deemed to need cleaning.

[0037] When the maximum irradiance value is 800W / m 2 <S<1000W / m 2 If the light transmittance τ of the photovoltaic panel is less than 90%, the photovoltaic panel under test is determined to need cleaning.

[0038] When the maximum irradiance value S≤800W / m 2 When the light transmittance τ of the photovoltaic panel is less than 85%, the photovoltaic panel under test is determined to need cleaning. This method can accurately determine the cleaning status of the photovoltaic panel under test.

[0039] The light transmittance of a photovoltaic panel refers to the light transmittance of the light emitted by the optical film typically installed on the panel. This film is used to reflect light off the panel surface and enhance the panel's light absorption efficiency. Dust will then adhere to the optical film, requiring cleaning.

[0040] In this embodiment, the light transmittance τ of the photovoltaic panel is determined by the following method:

[0041]

[0042] Among them: I 测 I represents the measured current output value of the photovoltaic panel under test. 标准 S represents the current output value of the photovoltaic panel under test under standard conditions. 标准 S represents the irradiance under standard conditions. 测The measured current output value of the photovoltaic panel under test is represented by T, the measured operating temperature of the photovoltaic panel under test is represented by a, and the current temperature coefficient of the photovoltaic panel under test is represented by a. By determining the transmittance in the above way, the accuracy of the results can be ensured without the need for special optical instruments. Moreover, environmental factors are fully considered, thus ensuring the accuracy of the final results.

[0043] Wherein: The standard test conditions refer to STC: irradiance 1000W / m 2 Battery temperature 25℃, AM1.5 spectrum.

[0044] The measured current output value S of the photovoltaic panel under test is determined by the following method. 测 :

[0045]

[0046] Wherein: S i d represents the irradiance value output by the i-th irradiance sensor. i The distance between the i-th irradiance sensor probe and the photovoltaic panel is represented by , and m represents the number of irradiance sensors. With the above structure, the irradiance of the photovoltaic panel is determined by multiple irradiance sensors, which can improve the accuracy of the final result.

[0047] Finally, 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 determining the cleaning state of a photovoltaic panel based on its output characteristics, characterized in that: Includes the following steps: S1. Arrange at least 3 irradiance sensors on the photovoltaic panel under test; S2. Obtain the irradiance value output by the irradiance sensor and simultaneously obtain the output current and operating temperature of the photovoltaic panel under test; S3. Determine the transmittance of the photovoltaic panel under test based on irradiance, output current, and operating temperature; S4. Obtain the maximum irradiance value at the location of the photovoltaic panel under test, and determine the cleaning status of the photovoltaic panel based on the historical irradiance value and the transmittance of the photovoltaic panel under test.

2. The method for determining the cleaning state of a photovoltaic panel based on its output characteristics according to claim 1, characterized in that: Step S4 specifically includes: The maximum irradiance value is selected from the irradiance values ​​at the location of the photovoltaic panel; When the maximum irradiance value S is greater than or equal to 1000 W / m 2 If the light transmittance τ of the photovoltaic panel is less than 95%, the photovoltaic panel under test is deemed to need cleaning. When the maximum irradiance value is 800W / m 2 <S<1000W / m 2 If the light transmittance τ of the photovoltaic panel is less than 90%, the photovoltaic panel under test is determined to need cleaning. When the maximum irradiance value S≤800W / m 2 If the light transmittance τ of the photovoltaic panel is less than 85%, the photovoltaic panel under test is determined to need cleaning.

3. The method for determining the cleaning state of a photovoltaic panel based on its output characteristics according to claim 2, characterized in that: The light transmittance τ of the photovoltaic panel is determined by the following method: Among them: I 测 I represents the measured current output value of the photovoltaic panel under test. 标准 S represents the current output value of the photovoltaic panel under test under standard conditions. 标准 S represents the irradiance under standard conditions. 测 The measured current output value of the photovoltaic panel under test is represented by T, the measured operating temperature of the photovoltaic panel under test is represented by a, and the current temperature coefficient of the photovoltaic panel under test is represented by a.

4. The method for determining the cleaning state of a photovoltaic panel based on its output characteristics according to claim 3, characterized in that: The measured current output value S of the photovoltaic panel under test is determined by the following method. 测 : Wherein: S i d represents the irradiance value output by the i-th irradiance sensor. i This represents the distance between the i-th irradiance sensor probe and the photovoltaic panel.

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