Construction method of floating type photovoltaic module dynamic coupling thermal-electric model

Abstract

The invention provides a method for constructing a dynamic coupling thermal-electric model of a floating photovoltaic module. The method comprises the following steps: constructing a power generation model based on a five-parameter single-diode equivalent circuit physical model of the photovoltaic module; establishing a thermal model according to the internal structure of the photovoltaic module, the layout form of the photovoltaic module in the water area and the heat exchange mode of the photovoltaic module and the surrounding environment; the meteorological environment parameters, the parameters of the photovoltaic module and the temperatures of all layers of the photovoltaic module at the moment i are input into a power generation model, power is obtained, i is larger than or equal to 0, and when i is equal to 0, the photovoltaic module is initialized; inputting heat transfer data, meteorological environment parameters, parameters and power of the photovoltaic module in different layout forms of the photovoltaic module in a water area into a thermal model, and outputting the temperature of each layer of the photovoltaic module at the (i + 1) moment under different layout forms; and under the condition that the difference value between the temperature of each layer of the photovoltaic module at the (i + 1) moment and the temperature at the i moment is smaller than a preset threshold value, a dynamic coupling thermal-electric model is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of clean energy and photovoltaic power generation, and in particular relates to a method for constructing a dynamic coupled thermal-electric model of a floating photovoltaic assembly. Background Art

[0002] Today, we are at a critical moment in the transformation of the energy system. The transition to an ideal net-zero carbon society requires efficient and cheap renewable energy. In this context, the rapid development of the photovoltaic industry has promoted the innovation of photovoltaic module deployment. The emergence of floating photovoltaic modules enables photovoltaic modules to be deployed on the surface of water bodies such as lakes, reservoirs, ponds and offshore waters. However, in the current research on floating photovoltaic modules, the relationship between the thermal and electrical properties of photovoltaic modules is always ignored, resulting in the inability to accurately calculate the thermoelectric characteristics of floating photovoltaic modules. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a method for constructing a dynamic coupled thermal-electric model of a floating photovoltaic module, in order to solve the above technical problems. In this regard, the technical solution provided by the present invention is as follows.

[0004] According to an embodiment of the present invention, a method for constructing a dynamic coupled thermal-electric model of a floating photovoltaic module includes: constructing a power generation model suitable for a floating photovoltaic module based on a five-parameter single diode equivalent circuit physical model of the photovoltaic module; establishing a thermal model suitable for the floating photovoltaic module according to the internal structure of the photovoltaic module, the layout of the photovoltaic module in the water area, and the heat exchange mode between the photovoltaic module and the surrounding environment, wherein the thermal model is used to characterize the energy balance between the layers of the photovoltaic module;

[0005] The following iterative calculation steps are performed to establish a dynamic coupled thermal-electric model of floating photovoltaic modules: meteorological environmental parameters, photovoltaic module parameters and the temperature of each layer of the photovoltaic module at time i are input into the power generation model to obtain the power of the photovoltaic module at time i, wherein i ≥ 0, and i = 0 indicates that the photovoltaic module is initialized; heat transfer data of photovoltaic modules in different layout forms in water areas, meteorological environmental parameters, photovoltaic module parameters and power are input into the thermal model, and the temperature of each layer of the photovoltaic module in different layout forms at time i+1 is output; when the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than a preset threshold, a dynamic coupled thermal-electric model associated with the thermal model and the power generation model is obtained.

[0006] In an embodiment of the present invention, a power generation model suitable for floating photovoltaic modules is constructed based on the five-parameter single diode equivalent circuit model of photovoltaic modules; then, according to the structural characteristics of photovoltaic modules and the layout form of the water area where photovoltaic modules are laid out, the heat exchange mode is analyzed, and a thermal model is established based on energy balance, which considers the multi-layer structure inside the photovoltaic modules and the thermal conduction, thermal convection and thermal radiation associated with different layout forms. Photovoltaic modules release heat during the power generation process, and the heat is transferred outward layer by layer to affect the operating state of the photovoltaic modules. Therefore, in the process of establishing a dynamic coupled thermal-electric model of floating photovoltaic modules, the meteorological environment parameters, the parameters of the photovoltaic modules and the temperature of the photovoltaic modules at time i (i≥0, i=0 indicates the initialization of the photovoltaic modules) are input into the electrical model, and the power of the photovoltaic modules at time i can be calculated. Subsequently, the heat transfer data, meteorological environment parameters, and parameters of photovoltaic modules under different layout forms in the water area are input into the thermal model. According to the multi-layer structure and different layout forms inside the photovoltaic module, the temperature of each layer of the photovoltaic module at time i+1 can be obtained through the thermal model. The power of the power generation model is iteratively updated while updating the temperature of each layer inside the photovoltaic module, until the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, and a dynamic coupled thermal-electric model associated with the thermal model and the power generation model is established. The dynamic coupled thermal-electric model fully considers the thermal and electrical feedback relationship of the floating photovoltaic module, realizes the coupled analysis of thermal and electrical characteristics, fills the gap that the thermal and electrical characteristics of the photovoltaic module cannot be effectively evaluated under different layout forms, helps to achieve accurate evaluation of the performance of floating photovoltaic modules, and is also conducive to the further promotion of floating photovoltaic modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Schematic diagram of heat transfer of photovoltaic modules in different layout forms in water areas according to an embodiment of the present invention;

[0008] Figure 2 A schematic diagram of a process for constructing a dynamic coupled thermal-electric model of a photovoltaic module in an embodiment of the present invention;

[0009] Figure 3A A comparison diagram of the actually measured power and temperature of the photovoltaic module in spring in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model;

[0010] Figure 3B A comparison diagram of the actually measured power and temperature of the photovoltaic module in summer in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model;

[0011] Figure 3CA comparison diagram of the actually measured power and temperature of the photovoltaic module in autumn in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model;

[0012] Figure 3D This is a comparison chart of the actually measured power and temperature of the photovoltaic module in winter in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model. DETAILED DESCRIPTION

[0013] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0014] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0015] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0016] As we all know, the higher temperature of photovoltaic modules will have an adverse effect on the semiconductors in the photovoltaic modules, thereby reducing the life and conversion efficiency of the photovoltaic modules. The deployment of floating photovoltaic modules near water bodies may cause the operating temperature of photovoltaic modules to decrease. Whether it will affect the working efficiency of photovoltaic modules has become an important reason for its attention. However, whether the lower operating temperature is a common feature of all floating photovoltaic modules is still controversial, and there are doubts about its thermal and electrical performance advantages. In addition, the relationship between the thermal and electrical properties of photovoltaic modules is always ignored in the research methods for floating photovoltaic modules, or the two are analyzed in isolation. At the same time, the existing modeling and simulation methods of coupled thermal-electrical characteristics of photovoltaic modules are mainly aimed at traditional (land-based) photovoltaic modules, which simplifies the photovoltaic module model to varying degrees and ignores some heat transfer mechanisms, such as heat exchange between photovoltaic modules and the surrounding water environment. As a result, the existing coupled thermal-electrical characteristics model does not fully consider the coupled feedback relationship between the thermal and electrical properties of photovoltaic modules in the water environment, and thus cannot accurately evaluate the characteristics of photovoltaic modules.

[0017] In this regard, the present invention fully considers the heat transfer mechanism of floating photovoltaic modules in water environment under different layout forms, couples the feedback relationship between the thermal and electrical performances of photovoltaic modules, and establishes a method for constructing a dynamic coupled thermal-electric model of floating photovoltaic modules, which can realize dynamic and accurate evaluation of the performance of floating photovoltaic modules.

[0018] Specifically, the present invention provides a method for constructing a dynamic coupled thermal-electric model of a floating photovoltaic module, comprising: constructing a power generation model suitable for a floating photovoltaic module based on a five-parameter single diode equivalent circuit physical model of the photovoltaic module; establishing a thermal model suitable for the floating photovoltaic module according to the internal structure of the photovoltaic module, the layout of the photovoltaic module in the water area, and the heat exchange method between the photovoltaic module and the surrounding environment, and the thermal model is used to characterize the energy balance between each layer of the photovoltaic module. Subsequently, the following iterative calculation steps are performed to establish a dynamic coupled thermal-electric model of the floating photovoltaic module: the meteorological environment parameters, the parameters of the photovoltaic module and the temperature of each layer of the photovoltaic module at time i are input into the power generation model to obtain the power of the photovoltaic module at time i, wherein i ≥ 0, and i = 0 indicates the initialization of the photovoltaic module; the heat transfer data of the photovoltaic module in different layout forms in the water area, the meteorological environment parameters, the parameters and the power of the photovoltaic module are input into the thermal model, and the temperature of each layer of the photovoltaic module in different layout forms at time i+1 is output; when the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, the dynamic coupled thermal-electric model associated with the thermal model and the power generation model is obtained.

[0019] In an embodiment of the present invention, the meteorological environment parameters, the parameters of the photovoltaic module and the temperature of the photovoltaic module at time i are input into the electrical model established based on the five-parameter single diode equivalent circuit physical model of the photovoltaic module, and the power of the photovoltaic module at time i can be calculated, wherein i≥0, i=0 indicates the initialization of the photovoltaic module, and the temperature of each layer of the initialized photovoltaic module can be the ambient temperature. Subsequently, the heat transfer data, meteorological environment parameters and parameters of the photovoltaic module under different layout forms in the water area are input into the thermal model, and according to the multi-layer structure inside the photovoltaic module and its different layout forms, the temperature of each layer of the photovoltaic module at time i+1 can be obtained through the thermal model, wherein the thermal model is established according to the internal structure of the photovoltaic module, the layout form of the photovoltaic module in the water area, and the heat exchange mode between the photovoltaic module and the surrounding environment to characterize the energy balance between the layers of the photovoltaic module. By iteratively updating the power of the power generation model and the temperature of each layer of the photovoltaic module, until the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, a dynamic coupled thermal-electric model associated with the thermal model and the power generation model is established. This dynamic coupled thermal-electric model fully considers the thermal and electrical feedback relationship of floating photovoltaic modules, realizes the coupled analysis of thermal and electrical performance, fills the gap that the thermal and electrical performance of photovoltaic modules cannot be effectively evaluated under different layout forms, helps to achieve accurate evaluation of the performance of floating photovoltaic modules, and is also conducive to the further promotion of floating photovoltaic modules.

[0020] According to an embodiment of the present invention, before executing the iteration step, the method further includes: presetting a time increment Δt and an end time t of establishing a dynamic coupled thermal-electric model. max , as a calculation parameter of the iterative calculation step. The method for constructing the dynamic coupled thermal-electric model of the floating photovoltaic assembly also includes: when the end time t of the dynamic coupled thermal-electric model is greater than or equal to the preset end time t max In this case, the dynamic coupled thermal-electric model is used to output the power of the photovoltaic module, the temperature of each layer of the photovoltaic module, the current-voltage curve and the power-voltage curve.

[0021] In the embodiment of the present invention, when the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, after the dynamic coupled thermal-electric model is established, the end time of the dynamic coupled thermal-electric model has not yet reached the preset end time t maxAt this time, it is necessary to use each time increment △t as the time increment for iterative calculation to iteratively calculate the power generation model and thermal model. The power generation model is used to calculate the saturation current, open circuit voltage, short circuit current and threshold (such as maximum value) power point voltage and current of the photovoltaic module; the thermal model calculates and analyzes and outputs the temperature of each layer of the photovoltaic module. By continuously iterating the calculation with the time increment △t until it is greater than or equal to the preset end time t of establishing the dynamic coupled thermal-electric model max , stop the iterative calculation. This method can improve the calculation accuracy of the output power and PV module temperature of the dynamic coupled thermal-electric model, which is conducive to more accurate evaluation of the thermal and electrical performance of the PV module. It should be noted that the calculation of the power generation model and the thermal model can be realized within a single time increment △t, and the iterative calculation can also be performed over a duration containing multiple time increments △t.

[0022] For example, at the initial moment (i.e., i=0), the photovoltaic module has not started working yet, and the temperature of each layer of the photovoltaic module is initialized to the ambient temperature, such as 25°C. When the photovoltaic module starts working, the meteorological environment parameters, the parameters of the photovoltaic module, and the temperature of each layer of the initialized photovoltaic module are input into the power generation model, and the power of the photovoltaic module in the working time period (e.g., 10 minutes, i.e., i=10) can be obtained. As the photovoltaic module starts to work and outputs electrical energy, heat transfer is accompanied. The heat transfer data, meteorological environment parameters, parameters and power of the photovoltaic module in different layout forms in the water area are input into the thermal model, and the temperature of each layer of the photovoltaic module in the working time period (e.g., 10 minutes, i.e., i=10) can be obtained. At this time, if the difference between the temperature of each layer of the photovoltaic module in the working time period and the temperature of each layer of the initialized photovoltaic module is greater than the preset threshold, the temperature in the working time period (e.g., 10 minutes, i.e., i=10) is used as the new iterative calculation parameter to calculate the power of the photovoltaic module in the new working time period (e.g., after accumulating 20 minutes of work, i.e., i=20) and the temperature of each layer of the photovoltaic module. Through continuous iterative calculation, until the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, the dynamic coupled thermal-electric model associated with the thermal model and the power generation model is obtained. Furthermore, when the temperature of each layer of the photovoltaic module meets the convergence requirements and the end time t of the dynamic coupled thermal-electric model is less than the preset end time t max In the case of , a single time increment △t is used as the iterative calculation parameter, and iterations are performed continuously until the end time t of the dynamic coupled thermal-electric model is greater than or equal to the preset end time t max , and then through the dynamic coupled thermal-electric model, the power of the photovoltaic module, the temperature of each layer of the photovoltaic module, the current-voltage curve and the power-voltage curve are output.

[0023] According to an embodiment of the present invention, taking a basic photovoltaic module unit as an example, the internal structure of the photovoltaic module includes: a glass layer, a first ethylene-vinyl acetate copolymer layer (EVA1 layer), a silicon wafer layer, a second ethylene-vinyl acetate copolymer layer (EVA2 layer) and a backplane layer. Therefore, according to the heat exchange characteristics of the photovoltaic module with the surrounding environment under the water environment conditions and the layout form of the photovoltaic module in the water area, the present invention analyzes the heat transfer mode of the photovoltaic module and considers the internal structure composition of the photovoltaic module, and establishes a thermal model of a five-layer structure, namely, a thermal model of a glass layer, an EVA1 layer, a silicon wafer layer, an EVA2 layer and a backplane layer, and the thermal model is used to characterize the energy balance of each layer of the photovoltaic module. Among them, the parameters of the photovoltaic module include: at least one of the number of layers of the photovoltaic module, the thickness of each layer, the material of each layer, the characteristics of the material of each layer, the characteristic parameters of the photovoltaic module, the layout form of the photovoltaic module in the water area, the tilt angle of the photovoltaic module and the panel area of ​​the photovoltaic module. For example: the material characteristics include: at least one of the density, specific heat, and thermal conductivity of the material; the number of layers of the photovoltaic module is, for example, five layers; the characteristic parameters of the photovoltaic module include: the type of silicon wafer layer in the photovoltaic module (such as the silicon wafer layer is polycrystalline silicon), the number of photovoltaic modules, and the rated power of the photovoltaic module, open circuit voltage, short circuit current, threshold (such as maximum value) power point current, threshold (such as maximum) power point voltage, and power temperature coefficient. The gas phase environmental parameters include: at least one of the ambient temperature, ambient temperature under the backplane layer, water temperature, solar radiation, and wind speed.

[0024] According to an embodiment of the present invention, the power generation model of the present invention applicable to the floating photovoltaic module is derived from the five-parameter single diode equivalent circuit physical model of the photovoltaic module, and a simplified engineering model applicable to the floating photovoltaic module is obtained by building a simulation model based on the model, and the simulation model can be built by a programmable software platform. Further, the power generation model of the present invention includes: a current model and a voltage model.

[0025] According to an embodiment of the present invention, the meteorological environment parameters, the parameters of the photovoltaic module and the temperature of each layer of the photovoltaic module at time i are input into the power generation model, and the power of the photovoltaic module at time i is obtained by: inputting the solar radiation G, the silicon layer temperature T C , Current temperature coefficient , and the current at the threshold (such as maximum) power point of the PV module under standard test conditions 、Solar irradiation G ref , the temperature of the photovoltaic module T ref Input into the power generation model to obtain the current at the threshold power point of the photovoltaic module silicon layer temperature at time i , where ref represents the standard test conditions. It should be noted that at the initial moment (i.e., when i=0), the photovoltaic module does not start working, and the temperature of the photovoltaic module is the ambient temperature.

[0026] Specifically, the current at the threshold power point at the silicon layer temperature of the photovoltaic module It can be calculated by the current model shown in formula (1):

[0027] (1).

[0028] For example: the solar radiation G and silicon layer temperature T of the photovoltaic module after working for 10 minutes C , Current temperature coefficient etc. are input into the current model, and the silicon layer of the photovoltaic module can be calculated at T C Current at threshold power point at temperature .

[0029] The voltage temperature coefficient of the photovoltaic module , compensation coefficient , silicon layer temperature T C , solar irradiance G, and the temperature of the PV module under standard test conditions T ref 、Solar irradiation G ref and the voltage at the threshold power point of the photovoltaic module Input into the power generation model to obtain the voltage of the threshold power point at the silicon layer temperature of the photovoltaic module at time i , where the voltage at the threshold power point of the photovoltaic module silicon layer temperature at time i can be calculated by the voltage model shown in formula (2):

[0030] (2).

[0031] Thus, according to the current at the threshold power point and voltage , the power of the photovoltaic module at time i is obtained, where the power P is calculated using the power generation model shown in formula (3):

[0032] (3).

[0033] According to an embodiment of the present invention, the thermal model is used to characterize the energy balance between the layers of the photovoltaic module. Therefore, the thermal model for the five-layer structure of the photovoltaic module of the present invention includes: the energy balance equation of the glass layer, the energy balance equation of the first ethylene-vinyl acetate copolymer layer (EVA1), the energy balance of the silicon wafer layer, the energy balance of the second ethylene-vinyl acetate copolymer layer (EVA2), and the energy balance of the backplane layer.

[0034] Specifically, the energy balance equation of the glass layer is used to characterize: the heat of the glass layer, the total amount of solar radiation absorbed by the glass layer, and the heat Q transferred by heat conduction between the glass layer and the first ethylene-vinyl acetate copolymer layer EVA1_g , the heat Q transferred by thermal radiation between the glass layer and the skyrad,g_sky , and the heat Q transferred by heat convection between the glass layer and the air conv,g_a There is an energy balance.

[0035] The energy balance equation of the first ethylene-vinyl acetate copolymer layer is used to characterize: the heat of the first ethylene-vinyl acetate copolymer layer and the heat Q transferred by heat conduction between the first ethylene-vinyl acetate copolymer layer and the silicon wafer layer C_EVA1 , the heat Q transferred by heat conduction between the glass layer and the first ethylene-vinyl acetate copolymer layer EVA1_g There is an energy balance.

[0036] The energy balance equation of the silicon wafer layer is used to characterize: the heat of the silicon wafer layer, the total amount of solar radiation absorbed by the silicon wafer layer, the power generation power, and the heat Q transferred by heat conduction between the first ethylene-vinyl acetate copolymer layer and the silicon wafer layer C_EVA1 , the heat Q transferred by heat conduction between the silicon layer and the second ethylene-vinyl acetate copolymer layer C_EVA2 There is an energy balance.

[0037] The energy balance equation of the second ethylene-vinyl acetate copolymer layer is used to characterize: the heat of the second ethylene-vinyl acetate copolymer layer and the heat Q transferred by heat conduction between the silicon wafer layer and the second ethylene-vinyl acetate copolymer layer C_EVA2 , the heat Q transferred by heat conduction between the backing layer and the second ethylene-vinyl acetate copolymer layer EVA2_BS There is an energy balance.

[0038] The energy balance of the backplane layer is used to characterize: the heat of the backplane layer, and the heat Q transferred by heat conduction between the backplane layer and the second ethylene-vinyl acetate copolymer layer EVA2_BS , the heat Q transferred between the back plate layer and the surrounding environment BS_loss There is an energy balance.

[0039] Specifically, the energy balance equation calculation method for the five-layer structure of a photovoltaic module is as follows:

[0040] Glass layer: (4);

[0041] EVA1 layer: (5);

[0042] Silicon wafer layer: (6);

[0043] EVA2 layer: (7);

[0044] Backplane layer: (8).

[0045] Among them, c p is the specific heat, is the thickness, A is the area of ​​the photovoltaic module panel, is the density, is the absorption rate, is the transmittance, G is the solar radiation, P is the power of the photovoltaic module, Q EVA1_g Q is the heat transferred by heat conduction between the EVA1 layer and the glass layer. rad,g_sky is the heat transferred by thermal radiation between the glass layer and the sky, Q conv,g_a Q is the heat transferred by heat convection between the glass layer and the air. C_EVA1 Q is the heat transferred by thermal conduction between the silicon layer and the EVA1 layer. C_EVA2 Q is the heat transferred by thermal conduction between the silicon layer and the EVA2 layer. EVA2_BS Q is the heat transferred by thermal conduction between the EVA2 layer and the backplane layer. BS_loss is the heat transferred between the backplane layer of the photovoltaic module and the surrounding environment; T is temperature, t is time, rad in the subscript is radiation heat transfer, conv is convection heat transfer, g is glass or glass layer, C is silicon material or silicon wafer layer, and BS is backplane material or backplane layer.

[0046] In formula (4), the heat Q transferred by heat conduction between the EVA1 layer and the glass layer is EVA1_g Calculated by the method shown in formula (9):

[0047] (9);

[0048] Among them, T EVA1 is the temperature of EVA1 layer, T g is the glass layer temperature, R EVA1_g is the thermal resistance between the EVA1 layer and the glass layer.

[0049] In equation (4), the heat Q transferred by thermal radiation between the glass layer and the sky is rad,g_sky Calculated by the method shown in formula (10):

[0050] (10);

[0051] Among them, T sky is the sky temperature, R rad,g_sky is the thermal resistance between the glass layer and the sky atmosphere.

[0052] In equation (4), the heat Q transferred by heat convection between the glass layer and the air is conv,g_a Calculated by the method shown in formula (11):

[0053] (11);

[0054] Among them, T amb is the ambient temperature, Rconv,g_a is the convection thermal resistance of the glass layer.

[0055] In equation (5) or (6), the heat Q transferred by heat conduction between the silicon layer and the EVA1 layer is C_EVA1 Calculated by the method shown in formula (12):

[0056] (12);

[0057] Among them, T C is the silicon layer temperature, R C_EVA1 is the thermal resistance between the silicon wafer layer and the EVA1 layer.

[0058] In equation (6) or (7), the heat Q transferred by heat conduction between the silicon layer and the EVA2 layer is C_EVA2 Calculated by the method shown in formula (13):

[0059] (13);

[0060] Among them, T EVA2 is the temperature of EVA2 layer, R C_EVA2 is the thermal resistance between the silicon wafer layer and the EVA2 layer.

[0061] In equation (7) or (8), the heat Q transferred by heat conduction between the EVA2 layer and the backplane layer is EVA2_BS Calculated by the method shown in formula (14):

[0062] (14);

[0063] Among them, T BS is the backplane layer temperature, R EVA2_BS is the thermal resistance between EVA2 and the backplane layer.

[0064] Figure 1 Schematic diagram of heat transfer of photovoltaic modules in different layout forms in water areas according to an embodiment of the present invention.

[0065] According to an embodiment of the present invention, Figure 1 As shown in the figure, the layout of photovoltaic modules in water areas includes: photovoltaic modules are arranged tilted (i.e., the tilt angle of photovoltaic modules θ>0°), photovoltaic modules are arranged horizontally and not in contact with water bodies (i.e., the tilt angle of photovoltaic modules θ=0°), and photovoltaic modules are arranged horizontally and the back panels of photovoltaic modules are in direct contact with water bodies. The different layouts of photovoltaic modules in water areas result in various forms of heat transfer between the back panel layer of the modules and the surrounding environment. BS_loss , which causes the heat transfer of the PV module backplane layer to affect the temperature of the PV module silicon layer and the heat transfer of the entire PV module, thereby affecting the accuracy of the dynamic coupled thermal-electric model evaluation.

[0066] According to an embodiment of the present invention, when the photovoltaic modules are arranged obliquely and the photovoltaic modules are arranged at an inclination angle θ>0°, the heat Q transferred between the module back plate layer and the surrounding environment is BS_loss Including: the heat Q transferred by the heat convection between the back plate layer and the air under the back plate layer conv,BS_ab and the heat Q transferred by thermal radiation between the back plate layer and the water body rad,BS_w .

[0067] Specifically, when the photovoltaic module is arranged at an inclination angle θ>0°, Q BS_loss It can be calculated by the method shown in formula (15):

[0068] (15);

[0069] Among them, Q conv,BS_ab Q is the heat transferred by thermal convection between the back plate layer and the air under the back plate layer. rad,BS_w It is the heat transferred by thermal radiation between the back plate layer and the water body.

[0070] Heat Q transferred by thermal radiation between the back plate layer and the water body rad,BS_w The radiation heat transfer coefficient between the back plate layer and the water below the back plate layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Specifically, the heat Q transferred by thermal radiation between the back plate layer and the water body is rad,BS_w The calculation method shown in the following formula (16) is used to calculate:

[0071] (16);

[0072] in, is the backplane layer temperature, is the water temperature, is the radiation heat transfer coefficient between the back sheet layer and the water body below the back sheet layer, and A is the area of ​​the photovoltaic module panel.

[0073] Furthermore, the radiation heat transfer coefficient between the back plate layer and the water below the back plate layer is Calculated by the method shown in formula (17):

[0074] (17);

[0075] in, is the Stefan-Boltzmann constant (5.67×10 -8 W / m 2 K 4 )、 is the emissivity of the back panel layer of the photovoltaic module, T BS is the backplane layer temperature, Tw is the water temperature.

[0076] Furthermore, the emissivity of the backplane layer of the photovoltaic module Calculated by the method shown in formula (18):

[0077] (18);

[0078] in, is the emissivity of the backplane layer, is the emissivity of the water body.

[0079] The heat Q transferred by thermal convection between the back plate layer and the air under the back plate layer conv,BS_ab The convection heat transfer coefficient between the back plate layer and the air under the back plate layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , Ambient temperature under the backsheet layer of photovoltaic modules Calculated.

[0080] Specifically, the heat Q transferred by thermal convection between the backplane layer and the air under the backplane layer is conv,BS_ab It is calculated by the method shown in the following formula (19):

[0081] (19);

[0082] in, is the ambient temperature under the backplane layer of the photovoltaic module, T BS is the backplane layer temperature, A is the area of ​​the photovoltaic module panel, is the convective heat transfer coefficient between the back plate layer and the air under the back plate layer.

[0083] Furthermore, the convective heat transfer coefficient between the back plate layer and the air under the back plate layer is Including: natural convection heat transfer coefficient between the back plate layer and the air under the back plate layer , forced convection heat transfer coefficient between the back plate layer and the air under the back plate layer Among them, the natural convection heat transfer coefficient between the back plate layer and the air under the back plate layer is The thermal conductivity k of air a , the characteristic length L of the photovoltaic module, the Nusselt number of natural convection in the backplane layer The forced convection heat transfer coefficient between the back plate layer and the air under the back plate layer is calculated. The thermal conductivity k of air a , the characteristic length L of the photovoltaic module, the Nusselt number of the forced convection of the backplane layer Calculated.

[0084] Specifically, the convective heat transfer coefficient between the back plate layer and the air under the back plate layer is It can be calculated by the following method as shown in equations (20) to (22):

[0085] (20);

[0086] (twenty one);

[0087] (twenty two);

[0088] in, The natural convection heat transfer coefficient between the back sheet layer and the air under the back sheet layer of the photovoltaic module, is the forced convection heat transfer coefficient between the back sheet layer and the air under the back sheet layer of the photovoltaic module, is the Nusselt number of natural convection in the back plate layer, is the Nusselt number of the forced convection in the back plate layer, k a is the thermal conductivity of air, and L is the characteristic length of the photovoltaic module.

[0089] Furthermore, when the photovoltaic module is arranged at an inclination angle of 2°<θ<90°, the natural convection Nusselt number of the backplane layer is It can be calculated by the method shown in formula (23)-formula (25):

[0090] (twenty three);

[0091] (twenty four);

[0092] (25);

[0093] Among them, Ra is the Rayleigh number, Gr is the Grashof number, Pr is the Prandtl number, g is the gravitational acceleration, is the isobaric volume expansion coefficient, θ is the inclination angle of the photovoltaic module layout (i.e. the angle between the photovoltaic module and the horizontal plane), is the kinematic viscosity, k a is the thermal conductivity of air, is the density, is the specific heat capacity.

[0094] When the photovoltaic module is arranged at an inclination angle of 0°<θ≤2°, the natural convection Nusselt number of the backplane layer It can be calculated by the method shown in formula (26)-formula (28):

[0095] (26);

[0096] (27);

[0097] (28).

[0098] Furthermore, when the tilt angle of the photovoltaic module is 0°<θ<90°, the Nusselt number of the forced convection of the backplane layer of the photovoltaic module is It can be calculated by the method shown in formula (29) to formula (31):

[0099] (29);

[0100] , (30);

[0101] (31);

[0102] Where Re is the Reynolds number, V mod The wind speed at the height where the PV panels are installed.

[0103] According to the embodiment of the present invention, when the photovoltaic module is arranged horizontally and not in contact with the water body (i.e., the inclination angle θ of the photovoltaic module is 0°), a limited closed space is formed between the back plate layer of the photovoltaic module, the float supporting the photovoltaic module and the surface of the water body. At this time, the heat Q transferred from the back plate layer of the module to the surrounding environment BS_loss Including: heat Q transferred by thermal radiation between the back plate layer and the water body rad,BS_w , the heat Q transferred by the back plate layer through heat conduction between the gas interlayer and the water body BS_a_w .

[0104] Specifically, when the tilt angle of the photovoltaic module is θ = 0°, the heat Q transferred between the back panel layer of the module and the surrounding environment is BS_loss It can be expressed as shown in formula (32):

[0105] (33);

[0106] Among them, Q BS_a_w Q is the heat transferred by the back plate layer through the heat conduction between the gas interlayer and the water body, rad,BS_w It is the heat transferred by thermal radiation between the back plate layer and the water body.

[0107] Furthermore, the heat Q transferred by thermal radiation between the back plate layer and the water body in equation (32) is rad,BS_w It can be calculated by the method shown in the above formula (16), and the heat Q transferred by the back plate layer through heat conduction between the gas interlayer and the water body is BS_a_w The heat transfer coefficient h can be obtained by the back plate layer through the air interlayer and the water body. BS_a_w , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T wCalculated.

[0108] Specifically, the heat Q transferred by heat conduction between the back plate layer and the water body through the gas interlayer is BS_a_w It can be calculated by the method shown in formula (34):

[0109] (34);

[0110] Among them, h BS_a_w It is the heat transfer coefficient between the back plate layer and the water through the air interlayer.

[0111] Furthermore, the heat transfer coefficient h of the back plate layer and the water body through the air interlayer is BS_a_w It can be calculated by the method shown in formula (35):

[0112] (35);

[0113] in, is the distance from the back panel of the floating photovoltaic module to the water surface, k a is the thermal conductivity of air.

[0114] According to an embodiment of the present invention, when the photovoltaic module is arranged horizontally and the back plate layer of the photovoltaic module is in direct contact with the water body, the heat Q transferred between the back plate layer of the module and the surrounding environment is BS_loss Including: heat Q transferred by heat conduction between the back plate layer and the water body BS_w , the heat Q transferred by thermal convection between the back plate layer and the water conv,BS_w .

[0115] Specifically, when the back sheet of a photovoltaic module is in direct contact with water, the heat Q transferred between the back sheet of the module and the surrounding environment is BS_loss It can be calculated by the method shown in formula (36):

[0116] (36);

[0117] Among them, Q BS_w is the heat transferred by heat conduction between the back plate layer and the water body, Q conv,BS_w It is the heat transferred by thermal convection between the back plate layer and the water body.

[0118] Furthermore, the heat Q transferred by heat conduction between the back plate layer and the water body is BS_w The thermal conductivity k of the backplane layer BS , the thickness of the backplane layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Specifically, the heat Q transferred by heat conduction between the back plate layer and the water body is BS_wIt can be calculated by the method shown in formula (37):

[0119] (37);

[0120] Among them, k BS is the thermal conductivity of the backplane layer, is the thickness of the back sheet layer, A is the area of ​​the photovoltaic module panel, T w is the water temperature, T BS is the backplane layer temperature.

[0121] Furthermore, the heat Q transferred by the heat convection between the back plate layer and the water body under the back plate layer is conv,BS_w The convective heat transfer coefficient between the back plate layer and the water body can be , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Calculated.

[0122] Specifically, the heat Q transferred by thermal convection between the back plate layer and the water body under the back plate layer is conv,BS_w It can be calculated by the method shown in formula (38):

[0123] (38);

[0124] in, is the convective heat transfer coefficient between the back plate layer and the water body, A is the area of ​​the photovoltaic module panel, T W is the water temperature, T BS is the backplane layer temperature.

[0125] Furthermore, the convective heat transfer coefficient between the back plate layer and the water body It can be calculated by the method shown in formula (39):

[0126] (39);

[0127] Among them, k w is the thermal conductivity of water, is the Nusselt number of convective heat transfer between the back plate layer and the water.

[0128] Furthermore, the Nusselt number of the convective heat transfer between the back plate layer and the water is It can be calculated by the method shown in formula (40):

[0129] (40);

[0130] in, is the kinematic viscosity of water, is the thermal diffusivity of water, is the Reynolds number of convective heat transfer between the back plate layer and the water body.

[0131] Reynolds number of convective heat transfer between the back plate layer and the water It can be calculated by the method shown in formula (41):

[0132] (41);

[0133] Among them, V w is the water flow rate, is the kinematic viscosity of water.

[0134] In order to make the technical solution of the present invention clearer, it is described in detail below with reference to specific embodiments and drawings.

[0135] Example 1

[0136] The floating photovoltaic modules used in this embodiment 1 are collected by real-time monitoring equipment set up in X city, X province. The real-time monitoring equipment is equipped with an IV curve detector for photovoltaic power generation monitoring, a meteorological element monitoring station, a temperature sensor of the photovoltaic module, a water temperature sensor, and an environmental element monitoring device under the back layer of the photovoltaic module. Among them, the IV curve detector monitoring parameters include the photovoltaic module current-voltage curve (IV curve), the power-voltage curve (PV curve), the threshold (such as maximum) power point voltage, the threshold (such as maximum) power point current, the open circuit voltage and the short circuit current; the meteorological environment parameters monitored by the meteorological element monitoring station include irradiance, irradiance at the tilt angle of the photovoltaic module, temperature, humidity, wind speed, wind direction and rainfall. The data collection frequency of the monitoring equipment used in the above monitoring is all at the minute level.

[0137] The interior of the photovoltaic module used in Example 1 is a five-layer structure, including: a glass layer, an EVA1 layer, a silicon layer, an EVA2 layer and a backplane layer. A thermal model is established based on the five-layer structure of the photovoltaic module, and heat is transferred layer by layer in the thermal model. Among them, it is assumed that: (i) energy transfer is one-dimensional and changes with time; (ii) heat conduction is uniform over the length and width of the photovoltaic module; (iii) the temperature at the center point of each layer of the photovoltaic module represents the average temperature of the layer; (iv) there is no contact resistance between the layers inside the photovoltaic module; (v) there is no heat transfer on the side of the photovoltaic module; (vi) the EVA1 layer does not absorb solar radiation. Based on the above assumptions, except for a small amount of solar radiation absorbed by the glass layer, part of the solar radiation enters the silicon layer for photoelectric reaction to generate electrical energy, and the rest becomes heat, which is transferred from the silicon layer to the outside layer by layer. For floating photovoltaic modules with different layout forms, the heat conducted from the inside of the photovoltaic module is transferred to the external environment in different forms between different objects, and its heat exchange mode involves heat conduction, heat convection and heat radiation.

[0138] Therefore, the present invention establishes a thermal model of a five-layer structure (i.e., glass layer, EVA1 layer, silicon wafer layer, EVA2 layer, and backplane layer) according to the heat exchange characteristics of photovoltaic modules and the surrounding environment under water environment conditions, the layout of photovoltaic modules in water areas, the heat transfer mode of photovoltaic modules, and the internal structure of photovoltaic modules. The thermal model is used to characterize the energy balance of each layer of the photovoltaic module, wherein the energy balance of each layer of the photovoltaic module is shown in the above formula (4) to formula (8). Furthermore, starting from the five-parameter single diode equivalent circuit physical model of the photovoltaic module, a power generation model suitable for the photovoltaic module is established. Combining the thermal model and the power generation model, a dynamic coupled thermal-electric model suitable for the photovoltaic module is established.

[0139] Figure 2 Schematic diagram of the process of constructing a dynamic coupled thermal-electric model of a photovoltaic module in an embodiment of the present invention.

[0140] like Figure 2 As shown, establishing a dynamic coupled thermal-electric model of a photovoltaic module includes steps S1-S10.

[0141] Step S1: Preset the time increment △t and end time t for establishing the dynamic coupled thermal-electrical model max , as the calculation parameter for the iterative calculation steps of establishing the dynamic coupled thermal-electric model of photovoltaic modules.

[0142] Step S2: Initialize the temperature and time of each layer of the photovoltaic module.

[0143] Step S3: input meteorological environment parameters and photovoltaic module parameters.

[0144] Step S4: In the power generation model, the voltage and current parameters under general conditions are calculated to obtain the power;

[0145] Step S5: In the thermal model, calculating the temperature of each layer of the photovoltaic module;

[0146] Step S6: Are the temperatures of each layer converged? That is, is the difference between the temperature of each layer of the photovoltaic module at time i+1 (i≥0, i=0 indicates the photovoltaic module is initialized) and the temperature at time i less than or equal to the preset threshold? If the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is greater than the preset threshold, execute step S7; if the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, execute step S8.

[0147] Step S7: = The power and the temperature of each layer of the photovoltaic module are calculated iteratively, where j>i, i≥0, j is a positive integer representing the number of iterative calculations; and i represents the working time of the photovoltaic module.

[0148] Step S8: When the difference between the temperature of each layer of the photovoltaic module at time i+1 and the temperature at time i is less than or equal to the preset threshold, determine whether the end time t of the dynamic coupled thermal-electric model is greater than or equal to the preset end time t max (t≥t max ? )? When the end time t of the dynamic coupled thermal-electric model is less than the preset end time t max In the case of, executing step S9; when the end time t of the dynamic coupled thermal-electric model is greater than or equal to the preset end time t max In this case, execute step S10.

[0149] Step S9: Using the preset time increment △t as the step length, t= +△t (k≥0, indicating time) to iteratively calculate the power and the temperature of each layer of the photovoltaic module until the end time t of the dynamic coupled thermal-electric model ≥ the preset end time t max .

[0150] Step S10: output power, temperature of each layer of the photovoltaic module and draw a current-voltage curve and a power-voltage curve.

[0151] The material physical property parameters of each layer of the photovoltaic module of the present invention are shown in Table 1.

[0152] Table 1

[0153]

[0154] The present invention uses the power generation monitoring data of a polycrystalline photovoltaic module with a rated power of 270Wp to verify the dynamic coupled thermal-electric model. Specifically, the characteristic parameters of the photovoltaic module are shown in Table 2.

[0155] Table 2

[0156]

[0157] In the area where the floating photovoltaic modules are located, the dynamic coupled thermal-electric model of the present invention is verified using the real-time monitoring data of floating photovoltaics on January 12, April 23, July 30, and September 14, 2021. The above test days involve the four seasons of winter, spring, summer, and autumn. The specific verification results are as follows: Figure 3A-3D shown.

[0158] Figure 3A A comparison diagram of the actually measured power and temperature of the photovoltaic module in spring in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model; Figure 3B A comparison diagram of the actually measured power and temperature of the photovoltaic module in summer in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model; Figure 3C A comparison diagram of the actually measured power and temperature of the photovoltaic module in autumn in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model; Figure 3D This is a comparison chart of the actually measured power and temperature of the photovoltaic module in winter in Example 1 of the present invention and the power and temperature of the photovoltaic module output by the dynamic coupled thermal-electric model.

[0159] like Figure 3A-3D As shown, the simulated calculation data of the power and photovoltaic module temperature by the dynamic coupled thermal-electric model are consistent with the real-time monitoring data in different seasons, indicating that the output accuracy of the dynamic coupled thermal-electric model of the present invention is relatively high. Table 3 shows the MAE (mean absolute error) and RMSE (standard error) of the dynamic coupled thermal-electric model of the present invention for the photovoltaic module temperature and power in the four seasonal test days.

[0160] Table 3

[0161]

[0162] As shown in Table 3, the MAE (mean absolute error) and RMSE (standard error) of the temperature and power of the photovoltaic modules of the dynamic coupled thermal-electric model of the present invention are low in the four seasonal test days. The difference between the simulated power value of the dynamic coupled thermal-electric model and the real-time monitored power value is significantly less than 10%, which also shows the accuracy and reliability of the dynamic coupled thermal-electric model established by the present invention.

[0163] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for constructing a dynamic coupled thermal-electric model of a floating photovoltaic module, comprising: Based on the five-parameter single-diode equivalent circuit physical model of photovoltaic modules, a power generation model suitable for floating photovoltaic modules is constructed; A thermal model suitable for a floating photovoltaic module is established according to the internal structure of the photovoltaic module, the layout of the photovoltaic module in the water area, and the heat exchange mode between the photovoltaic module and the surrounding environment, wherein the thermal model is used to characterize the energy balance between the layers of the photovoltaic module; The following iterative calculation steps are performed to establish a dynamic coupled thermal-electric model for floating photovoltaic modules: Inputting meteorological environment parameters, parameters of the photovoltaic module and the temperature of each layer of the photovoltaic module at time i into the power generation model to obtain the power of the photovoltaic module at time i, wherein i≥0, i=0 indicates initializing the photovoltaic module; Inputting heat transfer data of the photovoltaic modules in different layout forms in the water area, the meteorological environment parameters, the parameters of the photovoltaic modules and the power into the thermal model, and outputting the temperature of each layer of the photovoltaic modules at time i+1 in different layout forms; When the difference between the temperature of each layer of the photovoltaic component at time i+1 and the temperature at time i is less than or equal to a preset threshold, the dynamically coupled thermal-electric model associated with the thermal model and the power generation model is obtained.

2. The method according to claim 1, wherein: Before executing the iterative calculation step, the method further includes: The time increment △t and the end time t of the dynamic coupled thermal-electric model are preset. max , as calculation parameters for iterative calculation steps; and The method further comprises: When the end time t of the dynamic coupled thermal-electric model is greater than or equal to the preset end time t max In the case of a photovoltaic module, the dynamic coupled thermal-electric model is used to output the power of the photovoltaic module, the temperature of each layer of the photovoltaic module, the current-voltage curve and the power-voltage curve.

3. The method according to claim 1, wherein: The internal structure of the photovoltaic module includes: a glass layer, a first ethylene-vinyl acetate copolymer layer, a silicon sheet layer, a second ethylene-vinyl acetate copolymer layer and a back sheet layer; The meteorological environment parameters include: at least one of the ambient temperature, ambient temperature under the backing layer, water temperature, solar radiation, and wind speed; The parameters of the photovoltaic module include: the number of layers of the photovoltaic module, the thickness of each layer, the material of each layer, the characteristics of the material of each layer, the characteristic parameters of the photovoltaic module, the layout of the photovoltaic module in the water area, the inclination angle of the photovoltaic module and at least one of the panel area of ​​the photovoltaic module.

4. The method according to claim 3, wherein: The meteorological environment parameters, the parameters of the photovoltaic module and the temperature of each layer of the photovoltaic module at time i are input into the power generation model to obtain the power of the photovoltaic module at time i, including: The voltage temperature coefficient of the photovoltaic module , compensation coefficient , silicon layer temperature T C , solar radiation G, and the temperature T of the photovoltaic module under standard test conditions ref 、Solar irradiation G ref and the voltage at the threshold power point of the photovoltaic module Input into the power generation model to obtain the voltage of the threshold power point at the silicon layer temperature of the photovoltaic module at time i ; The solar radiation G, silicon layer temperature T C , Current temperature coefficient , and the current at the threshold power point of the photovoltaic module under standard test conditions 、Solar irradiation G ref , the temperature of the photovoltaic module T ref Input into the power generation model to obtain the current at the threshold power point of the photovoltaic module silicon layer temperature at time i ; According to the threshold power point current and voltage , and obtain the power of the photovoltaic module at time i.

5. The method according to claim 4, wherein: The thermal model includes: The energy balance equation of the glass layer is used to characterize: the heat of the glass layer, the total amount of solar radiation absorbed by the glass layer, and the heat Q transferred by heat conduction between the glass layer and the first ethylene-vinyl acetate copolymer layer EVA1_g , the heat Q transferred by thermal radiation between the glass layer and the sky rad,g_sky , and the heat Q transferred by heat convection between the glass layer and the air conv,g_a There is an energy balance; The energy balance equation of the first ethylene-vinyl acetate copolymer layer is used to characterize: the heat of the first ethylene-vinyl acetate copolymer layer and the heat Q transferred by heat conduction between the first ethylene-vinyl acetate copolymer layer and the silicon wafer layer C_EVA1 , the heat Q transferred by heat conduction between the glass layer and the first ethylene-vinyl acetate copolymer layer EVA1_g There is an energy balance; The energy balance equation of the silicon wafer layer is used to characterize: the heat of the silicon wafer layer, the total amount of solar radiation absorbed by the silicon wafer layer, the power generation power, and the heat Q transferred by heat conduction between the first ethylene-vinyl acetate copolymer layer and the silicon wafer layer C_EVA1 , the heat Q transferred by heat conduction between the silicon layer and the second ethylene-vinyl acetate copolymer layer C_EVA2 There is an energy balance; The energy balance equation of the second ethylene-vinyl acetate copolymer layer is used to characterize: the heat of the second ethylene-vinyl acetate copolymer layer and the heat Q transferred by heat conduction between the silicon wafer layer and the second ethylene-vinyl acetate copolymer layer C_EVA2 , the heat Q transferred by heat conduction between the backing layer and the second ethylene-vinyl acetate copolymer layer EVA2_BS There is an energy balance; The energy balance of the backplane layer is used to characterize: the heat of the backplane layer, and the heat Q transferred by heat conduction between the backplane layer and the second ethylene-vinyl acetate copolymer layer EVA2_BS , the heat Q transferred between the back plate layer and the surrounding environment BS_loss There is an energy balance.

6. The method according to claim 5, wherein: The heat Q transferred between the back plate layer and the surrounding environment BS_loss include: When the photovoltaic module is arranged at an inclination angle θ>0°, the heat Q transferred between the back plate layer and the surrounding environment BS_loss Including: the heat Q transferred by the heat convection between the back plate layer and the air under the back plate layer conv,BS_ab The heat Q transferred by the back plate layer and the water body through thermal radiation rad,BS_w ;or When the photovoltaic module is arranged at an inclination angle θ=0°, the heat Q transferred between the back plate layer and the surrounding environment is BS_loss Including: the heat Q transferred by thermal radiation between the back plate layer and the water body rad,BS_w , the heat Q transferred by the back plate layer through heat conduction between the gas interlayer and the water body BS_a_w ;or When the back sheet of the photovoltaic module is in direct contact with the water, the heat Q transferred between the back sheet and the surrounding environment BS_loss Including: the heat Q transferred by heat conduction between the back plate layer and the water body BS_w , the heat Q transferred by thermal convection between the back plate layer and the water body conv,BS_w .

7. The method according to claim 6, wherein: The heat Q transferred by thermal convection between the back plate layer and the air under the back plate layer conv,BS_ab The convection heat transfer coefficient between the back plate layer and the air under the back plate layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , Ambient temperature under the backsheet layer of photovoltaic modules Calculated; The heat Q transferred by thermal radiation between the back plate layer and the water body rad,BS_w The radiation heat transfer coefficient between the back plate layer and the water below the back plate layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Calculated; Among them, the convection heat transfer coefficient between the back plate layer and the air under the back plate layer is Including: natural convection heat transfer coefficient between the back plate layer and the air under the back plate layer , forced convection heat transfer coefficient between the back plate layer and the air under the back plate layer ; Among them, the natural convection heat transfer coefficient between the back plate layer and the air under the back plate layer is The thermal conductivity k of air a , the characteristic length L of the photovoltaic module, the Nusselt number of natural convection in the backplane layer Calculated; The forced convection heat transfer coefficient between the back plate layer and the air under the back plate layer The thermal conductivity k of air a , the characteristic length L of the photovoltaic module, the Nusselt number of the forced convection of the backplane layer Calculated.

8. The method according to claim 7, wherein: When the photovoltaic module is arranged at an inclination angle of 2°<θ<90°, the Nusselt number of the natural convection of the backplane layer is It is expressed as: ;or When the photovoltaic module is arranged at an inclination angle of 0°<θ≤2°, the Nusselt number of the natural convection of the backplane layer is It is expressed as: ; Wherein, Ra is the Rayleigh number.

9. The method according to claim 6, wherein: The heat Q transferred by heat conduction between the back plate layer and the water body through the gas interlayer BS_a_w The heat transfer coefficient h is the heat conduction coefficient between the back plate layer and the water through the air interlayer. BS_a_w , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Calculated.

10. The method according to claim 6, wherein: The heat Q transferred by heat conduction between the back plate layer and the water body BS_w The thermal conductivity k of the backplane layer BS , the thickness of the backplane layer , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Calculated; The heat Q transferred by thermal convection between the back plate layer and the water body under the back plate layer conv,BS_w The convective heat transfer coefficient between the back plate layer and the water , the area of ​​the photovoltaic panel A, the back panel temperature T BS , water temperature T w Calculated.

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