Method for determining irradiance coefficient and temperature coefficient of photovoltaic panel based on open-circuit voltage model

Abstract

The invention provides a method for determining an irradiance coefficient and a temperature coefficient of a photovoltaic panel based on an open-circuit voltage model. The method comprises the following steps: S1, cleaning a to-be-detected photovoltaic panel; s2, arranging the photovoltaic panel at a set position; s3, AM1.5 G neutral standard optical filters with different light transmittances are adopted to cover the photovoltaic panel in a vacuum mode, and the open-circuit voltage, the temperature and the irradiance of the photovoltaic panel under the different light transmittances are recorded; s4, taking down the AM1.5 G neutral standard optical filter, performing temperature intervention on the photovoltaic panel to reach a set intervention temperature when the temperature of the photovoltaic panel is lower than or higher than 25 DEG C, and recording the open-circuit voltage, the temperature and the irradiance of the photovoltaic panel in the process of recovering the photovoltaic panel from the set intervention temperature to the environment temperature; and S5, constructing a relation model of the open-circuit voltage, the temperature coefficient and the irradiance coefficient of the photovoltaic panel, substituting the data in the step S3 and the step S4 into the model, and then obtaining the irradiance coefficient and the temperature coefficient by adopting linear fitting software.

Description

TECHNICAL FIELD

[0001] The present application relates to a photovoltaic panel parameter determination method, in particular to a photovoltaic panel irradiance coefficient and temperature coefficient determination method based on an open-circuit voltage model. BACKGROUND

[0002] As the core component of a solar power generation system, the power generation efficiency of a photovoltaic panel (a common name for a photovoltaic cell assembly) is directly subject to environmental factors, among which the influence of irradiance and working temperature, two key parameters, is the most critical. These two parameters are crucial for the design, power generation prediction, performance evaluation, and fault diagnosis of a solar power generation system.

[0003] In the prior art, the determination of the irradiance and working temperature of a photovoltaic panel has the following defects: the acquisition of the irradiance coefficient usually depends on natural weather changes, and it is necessary to wait for stable sunny days with different irradiance intensities, which is a long process and is limited by season and region; the determination of the temperature coefficient requires a laboratory temperature control box or waiting for natural temperature rise / drop of the environment, which is a long cycle and is difficult to completely match the actual working conditions on site. The independent testing method of these two coefficients not only consumes time and effort, is costly, but also easily introduces environmental fluctuation interference (such as irradiance transients and temperature drifts) due to the large time span of the test, which leads to poor data synchronization and difficulty in ensuring measurement accuracy, seriously restricting the efficiency and reliability of on-site evaluation of photovoltaic systems.

[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 irradiance coefficient and temperature coefficient determination method based on an open-circuit voltage model, which can quickly and accurately determine the irradiance coefficient and temperature coefficient of a photovoltaic panel in an outdoor environment, effectively avoiding passive dependence on environmental factors while improving the accuracy of parameter determination, shortening the parameter determination process, and providing accurate and reliable data support for subsequent design, power generation prediction, etc. of photovoltaic power generation systems.

[0006] The present application provides a photovoltaic panel irradiance coefficient and temperature coefficient determination method based on an open-circuit voltage model, comprising the following steps:

[0007] S1. Clean the photovoltaic panel to be tested;

[0008] S2. Arrange the photovoltaic panel at a set position;

[0009] S3. Use AM1.5G neutral standard filters with different light transmittances to cover the photovoltaic panel in vacuum respectively, and record the open-circuit voltage, temperature, and irradiance of the photovoltaic panel under different light transmittances respectively;

[0010] S4. Remove the AM1.5G neutral standard filter, when the photovoltaic panel temperature is lower than 25℃, use the deionized warm water at the set temperature to spray the photovoltaic panel until the set intervention temperature, when the ambient temperature is higher than 25℃, use the deionized ice water to spray the photovoltaic panel until the set intervention temperature, and record the open-circuit voltage, temperature and irradiance of the photovoltaic panel during the process of the photovoltaic panel recovering from the set intervention temperature to the ambient temperature;

[0011] S5. Construct the open-circuit voltage and temperature coefficient and irradiance coefficient relationship model of the photovoltaic panel, and substitute the data in step S3 and step S4 into the model, and then use the linear fitting software to obtain the irradiance coefficient and the temperature coefficient.

[0012] Further, in step S4, the open-circuit voltage and temperature coefficient and irradiance coefficient relationship model of the photovoltaic panel is specifically:

[0013]

[0014] Wherein: β represents the temperature coefficient of the photovoltaic panel, κ represents the irradiance coefficient of the photovoltaic panel, G represents the measured irradiance of the photovoltaic panel, T represents the measured temperature of the photovoltaic panel, V oc,STC represents the open-circuit voltage value of the photovoltaic panel at the standard irradiance and the temperature of 25℃.

[0015] Further, in step S1, the surface cleaning of the photovoltaic panel to be tested specifically includes:

[0016] Spray the photovoltaic panel surface with deionized water after atomization by the atomizer, and then wipe the photovoltaic panel surface with non-woven fabric in one direction, wherein the resistivity of the deionized water is ≥18Ω·cm.

[0017] Further, step S2 specifically includes:

[0018] The set position of the photovoltaic panel arrangement meets the following conditions:

[0019] The set position weather needs to maintain continuous high irradiance, specifically cloud cover ≤10%, irradiance intensity ≥800W / m 2 and stable;

[0020] There are no obstacles within the set distance around the set position and the ground flatness error is ≤3°;

[0021] The environmental humidity of the set position is 40-60%.

[0022] Further, vacuum covering the photovoltaic panel with AM1.5G neutral standard filters with different light transmittance specifically includes:

[0023] The AM1.5G neutral standard filter with a light transmittance of 75%, 50% and 25% is vacuumed on the photovoltaic panel in descending order of light transmittance, and after each AM1.5G neutral standard filter is removed, the next AM1.5G neutral standard filter is covered after 5 minutes;

[0024] The distance between the AM1.5G neutral standard filter and the photovoltaic panel is less than 0.1mm.

[0025] Further, when the temperature of the photovoltaic panel is lower than 25℃, the deionized warm water with a set temperature is sprayed to heat the photovoltaic panel until the set intervention temperature, and when the ambient temperature is higher than 25℃, the deionized ice water is sprayed to cool the photovoltaic panel to the set intervention temperature, and the specific method comprises the following steps:

[0026] When the photovoltaic panel is heated, the set intervention temperature is the ambient temperature plus 15 degrees Celsius;

[0027] When the photovoltaic panel is cooled, the set intervention temperature is the ambient temperature minus 15 degrees Celsius;

[0028] The deionized warm water and the deionized ice water are atomized by using an atomizing device when spraying, and the diameter of the atomized particles is less than 50μm;

[0029] The distance between the spray nozzle and the photovoltaic panel is kept at 30cm;

[0030] After the photovoltaic panel is heated and cooled, the non-woven fabric is used for one-way wiping, so that the area of the residual water film is ≤5% of the area of the photovoltaic panel surface.

[0031] The beneficial effects of the present application are as follows: through the present application, the irradiance coefficient and the temperature coefficient of the photovoltaic panel can be quickly and accurately determined in an outdoor environment, the accuracy of parameter determination is improved, passive dependence on environmental factors is effectively avoided, the parameter determination process is shortened, and accurate and reliable data support is provided for subsequent design of a photovoltaic power generation system, power generation prediction and the like. BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in combination with the drawings and examples:

[0033] Figure 1 The present application is a flowchart. DETAILED DESCRIPTION

[0034] The present application will be further described below in combination with the drawings and examples:

[0035] The present application provides a method for determining the irradiance coefficient and the temperature coefficient of a photovoltaic panel based on an open-circuit voltage model, comprising the following steps:

[0036] S1. Cleaning the photovoltaic panel to be tested;

[0037] S2. Arranging the photovoltaic panel at a set position;

[0038] S3. Covering the photovoltaic panel with AM1.5G neutral standard filters of different transmittances in vacuum respectively, and recording the open-circuit voltage, temperature and irradiance of the photovoltaic panel under different transmittances respectively;

[0039] S4. Removing the AM1.5G neutral standard filter, when the temperature of the photovoltaic panel is lower than 25℃, spraying and heating the photovoltaic panel with deionized warm water at a set temperature until a set intervention temperature, when the ambient temperature is higher than 25℃, spraying and cooling the photovoltaic panel with deionized ice water to the set intervention temperature, and recording the open-circuit voltage, temperature and irradiance of the photovoltaic panel during the process of recovering the photovoltaic panel from the set intervention temperature to the ambient temperature;

[0040] S5. Constructing a model of the relationship between the open-circuit voltage of the photovoltaic panel and the temperature coefficient and the irradiance coefficient, and substituting the data in steps S3 and S4 into the model, and then using linear fitting software to obtain the irradiance coefficient and the temperature coefficient. The linear fitting software is, for example, Origin fitting software, etc. to obtain the irradiance coefficient and the temperature coefficient. Through the above method, the irradiance coefficient and the temperature coefficient of the photovoltaic panel can be quickly and accurately determined in an outdoor environment, which improves the accuracy of parameter determination, effectively avoids passive dependence on environmental factors, shortens the parameter determination process, and provides accurate and reliable data support for subsequent design of photovoltaic power generation system, power generation prediction, etc.

[0041] In this embodiment, in step S4, the model of the relationship between the open-circuit voltage of the photovoltaic panel and the temperature coefficient and the irradiance coefficient is specifically:

[0042]

[0043] Wherein β represents the temperature coefficient of the photovoltaic panel, κ represents the irradiance coefficient of the photovoltaic panel, G represents the measured irradiance of the photovoltaic panel, T represents the measured temperature of the photovoltaic panel, V oc,STC represents the open-circuit voltage value of the photovoltaic panel at standard irradiance and 25℃. Through the above model, the relationship model between the actual environmental irradiance and the temperature coefficient of the photovoltaic panel and the open-circuit voltage is established based on the open-circuit voltage value under standard environment (i.e. the open-circuit voltage value of the photovoltaic panel at standard irradiance and 25℃), the irradiance coefficient and the temperature coefficient, thereby providing guarantee for the determination of the temperature coefficient and the irradiance coefficient.

[0044] In this embodiment, in step S1, the surface cleaning of the photovoltaic panel to be tested specifically includes:

[0045] The deionized water is atomized by a sprayer and sprayed to the surface of the photovoltaic panel, and then a non-woven fabric is used to wipe the surface of the photovoltaic panel in one direction, wherein the resistivity of the deionized water is greater than or equal to 18 Ω·cm. The deionized water can effectively remove stains on the surface of the photovoltaic panel, and can also avoid corrosion of the photovoltaic panel. In addition, one-way wiping can avoid secondary pollution to the surface of the photovoltaic panel.

[0046] In this embodiment, step S2 specifically includes:

[0047] The set position of the photovoltaic panel arrangement satisfies the following conditions:

[0048] The set position needs to maintain continuous high irradiance weather, specifically, the cloud cover is less than or equal to 10%, and the irradiance intensity is greater than or equal to 800 W / m 2 and stable;

[0049] There is no obstacle within the set distance around the set position, and the ground flatness error is less than or equal to 3°; specifically:

[0050] The site must be in an open and unshielded environment, and there should be no building, tree or temporary obstacle projection within a range of 5 meters from the center of the photovoltaic panel to ensure that there is no shadow coverage when the angle of incidence of the sun changes. Based on the normal direction of the photovoltaic panel array, there should be no light-absorbing or light-reflecting objects (such as glass curtain walls and metal structures) within a 150° sector in the east-west direction and a range of 0-45° in the zenith angle.

[0051] The ground flatness error is less than or equal to 3°, which can avoid uneven irradiation caused by inclination differences.

[0052] The experimental window is limited to 2 hours before and after noon (calibrated time zone by GPS positioning) of the true sun,

[0053] The environmental humidity of the set position is between 40-60%, which can reduce the particle charge on the surface of the photovoltaic panel. When the humidity exceeds the set value, a particle blower is started to neutralize the charge on the surface of the photovoltaic panel.

[0054] During the test, the data collected by the data acquisition equipment also need to be recorded and sampled, i.e. the irradiance sensor and the temperature sensor.

[0055] The irradiance sensor and the photovoltaic panel have the following conditions:

[0056] The center of the irradiance sensor (irradiance meter) is 1±0.5m away from the edge of the photovoltaic panel; the height is the same as the upper edge of the photovoltaic panel, and the included angle between the probe normal and the photovoltaic panel normal is less than or equal to 0.5°;

[0057] The temperature sensor uses a PT1000 platinum resistance;

[0058] The end voltage of the photovoltaic panel is sampled at 1 kHz to prevent 50 Hz power frequency interference.

[0059] In the embodiment, the AM1.5G neutral standard filters with different light transmittances are respectively vacuum-covered on the photovoltaic panel, specifically comprising:

[0060] The AM1.5G neutral standard filters with light transmittances of 75%, 50% and 25% are vacuum-covered on the photovoltaic panel in descending order of light transmittance, and after each AM1.5G neutral standard filter is removed, the next AM1.5G neutral standard filter is covered again after 5 minutes; the interval of 5 minutes can make the photovoltaic panel fully heat dissipation, and the descending order arrangement of the filters can effectively avoid the thermal shock damage to the photovoltaic panel caused by temperature fluctuation.

[0061] The air gap between the AM1.5G neutral standard filter and the photovoltaic panel is less than 0.1 mm.

[0062] In the embodiment, when the temperature of the photovoltaic panel is lower than 25℃, the deionized warm water with a set temperature is used to spray and heat the photovoltaic panel until the set intervention temperature, and when the ambient temperature is higher than 25℃, the deionized ice water is used to spray and cool the photovoltaic panel to the set intervention temperature, specifically comprising:

[0063] When the photovoltaic panel is heated, the set intervention temperature is the ambient temperature plus 15 degrees Celsius;

[0064] When the photovoltaic panel is cooled, the set intervention temperature is the ambient temperature minus 15 degrees Celsius;

[0065] The deionized warm water and the deionized ice water are atomized by using an atomizing device when spraying, and the diameter of the atomized particles is less than 50μm;

[0066] The distance between the spray nozzle and the photovoltaic panel is kept at 30cm;

[0067] After the photovoltaic panel is heated and cooled, the non-woven fabric is used for one-way wiping to make the area of the residual water film ≤5% of the photovoltaic panel surface area.

[0068] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. 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 equivalently without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method for determining irradiance and temperature coefficients of a photovoltaic panel based on an open-circuit voltage model, characterized in that: The method comprises the following steps: S1. cleaning the photovoltaic panel to be tested; S2. arranging the photovoltaic panel at a set position; S3. covering the photovoltaic panel with AM1.5G neutral standard filters with different light transmittances in vacuum respectively, and recording the open-circuit voltage, temperature and irradiance of the photovoltaic panel under different light transmittances respectively; S4. removing the AM1.5G neutral standard filters, when the temperature of the photovoltaic panel is lower than 25℃, spraying and heating the photovoltaic panel with deionized warm water at a set temperature until a set intervention temperature, when the ambient temperature is higher than 25℃, spraying and cooling the photovoltaic panel with deionized ice water to the set intervention temperature, and recording the open-circuit voltage, temperature and irradiance of the photovoltaic panel in the process of recovering the photovoltaic panel from the set intervention temperature to the ambient temperature; S5. constructing a photovoltaic panel open-circuit voltage and temperature coefficient and irradiance coefficient relationship model, and substituting the data in steps S3 and S4 into the model, and then obtaining the irradiance coefficient and temperature coefficient by using linear fitting software.

2. The method for determining the irradiance and temperature coefficients of a photovoltaic panel based on the open-circuit voltage model according to claim 1, characterized in that: In step S4, the photovoltaic panel open-circuit voltage and temperature coefficient and irradiance coefficient relationship model is specifically as follows: wherein: β represents the temperature coefficient of the photovoltaic panel, κ represents the irradiance coefficient of the photovoltaic panel, G represents the measured irradiance of the photovoltaic panel, T represents the measured temperature of the photovoltaic panel, V oc,STC represents the open-circuit voltage value of the photovoltaic panel at standard irradiance and at a temperature of 25°C.

3. The method for determining the irradiance and temperature coefficients of a photovoltaic panel based on the open-circuit voltage model according to claim 1, characterized in that: In step S1, the cleaning of the surface of the photovoltaic panel to be tested specifically comprises: Spraying deionized water on the surface of the photovoltaic panel through an atomizer, and then wiping the surface of the photovoltaic panel with non-woven fabric in one direction, wherein the resistivity of the deionized water is greater than or equal to 18Ω·cm.

4. The method for determining irradiance and temperature coefficients of a photovoltaic panel based on open-circuit voltage model according to claim 1, characterized in that: In step S2, it specifically comprises: The set position of the photovoltaic panel arrangement meets the following conditions: The weather at the set position needs to be kept continuously high irradiance, specifically, cloud cover ≤ 10%, irradiance intensity ≥ 800 W / m 2 and stable; There are no obstacles within a set distance around the set position, and the ground flatness error is less than or equal to 3°; The ambient humidity at the set position is between 40% and 60%.

5. The method for determining irradiance and temperature coefficients of a photovoltaic panel based on open-circuit voltage model according to claim 1, characterized in that: Covering the photovoltaic panel with AM1.5G neutral standard filters with different light transmittances in vacuum specifically comprises: Covering the photovoltaic panel with AM1.5G neutral standard filters with light transmittances of 75%, 50% and 25% in descending order of light transmittance in vacuum, and each time after the AM1.5G neutral standard filter is removed, interval 5 minutes and then cover the next AM1.5G neutral standard filter; The air gap between the AM1.5G neutral standard filter and the photovoltaic panel is less than 0.1mm.

6. The method for determining irradiance and temperature coefficients of a photovoltaic panel based on open-circuit voltage model according to claim 1, characterized in that: When the temperature of the photovoltaic panel is lower than 25℃, spraying and heating the photovoltaic panel with deionized warm water at a set temperature until a set intervention temperature, when the ambient temperature is higher than 25℃, spraying and cooling the photovoltaic panel with deionized ice water to the set intervention temperature specifically comprises: When heating the photovoltaic panel, the set intervention temperature is the ambient temperature plus 15 degrees Celsius; When cooling the photovoltaic panel, the set intervention temperature is the ambient temperature minus 15 degrees Celsius; Spraying deionized warm water and deionized ice water through an atomizing device, and the diameter of the atomized particles is less than 50μm; The distance between the spraying nozzle and the photovoltaic panel is kept at 30cm; After spraying, non-woven fabric is used to wipe the photovoltaic panel in one direction, so that the area of the residual water film is less than or equal to 5% of the area of the photovoltaic panel.

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