Method for predicting working characteristics of photovoltaic cell under different illumination temperature conditions

Abstract

The invention provides a method for predicting working characteristics of a photovoltaic cell under different illumination and temperature conditions, and relates to the technical field of photovoltaic cells, and the method comprises the steps: selecting a reference condition, measuring voltage and current, and forming an I-V relation curve under the reference condition; any condition within the condition range of illumination G = 200W / m < 2 >-1000W / m < 2 > and module temperature T = 25-75 DEG C is selected as a test condition, and an open-circuit voltage Voc, a short-circuit current Isc and a fill factor FF under the test condition are obtained according to the relationship between the module temperature T and the open-circuit voltage Voc, the short-circuit current Isc and the fill factor FF; fitting a solar cell I-V relation curve under each test condition, and obtaining the maximum power point of the test condition; obtaining a plurality of I-V relation curves and a maximum power point under at least two test conditions; and performing curve fitting on the maximum power points under the at least two test conditions to obtain a maximum power point fitting curve.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and more specifically, to a method for predicting working characteristics of photovoltaic cells under different illumination and temperature conditions. Background Art

[0002] As a safe, efficient and convenient new energy device, photovoltaic cells have developed rapidly in recent years. Correspondingly, the study of photovoltaic cell characteristics has also become an important topic. Among them, the maximum power of photovoltaic cells is one of the key points of photovoltaic cell characteristic research.

[0003] The most direct way to obtain the output characteristic curve of a photovoltaic cell is to measure it directly using an IV curve tester. However, the measured output characteristic curve is only the output characteristic curve under a specific temperature and sunlight intensity, and this curve cannot represent the output characteristic curve under other temperatures and sunlight intensities.

[0004] At present, the working parameters of mass-produced batteries are basically tested under standard test conditions (STC: 1kW / m2 irradiance, 25℃ module temperature and AM1.5 global spectrum). The parameters of solar cells such as short-circuit current, open-circuit voltage and fill factor will change with temperature and irradiance. During the use of photovoltaic panels, their working characteristics will change significantly with changes in light and temperature conditions. Therefore, the prediction of the working characteristics of photovoltaic cells is of great significance and is related to the utilization efficiency of photovoltaic power generation.

[0005] Therefore, studying the temperature dependence of solar cells and modules is very important for evaluating the actual output of solar cells and modules. The current single measurement standard for mass-produced cells and modules cannot clearly define the parameter changes of TOPCON cells and modules under different temperatures and irradiances. Summary of the invention

[0006] In view of this, the present invention provides a method for predicting the working characteristics of photovoltaic cells under different lighting temperature conditions, aiming to improve the problem that the prior art cannot clearly predict the parameter changes of photovoltaic cells under different temperatures and irradiances.

[0007] The present invention provides a method for predicting the working characteristics of a photovoltaic cell under different illumination and temperature conditions, comprising the following steps:

[0008] Select a certain condition as a reference condition, measure the voltage and current data of the solar cell under the reference condition, and form an IV relationship curve of the solar cell under the reference condition;

[0009] Select light G = 200W / m 2 -1000W / m 2Any condition within the range of module temperature T = 25°C-75°C is used as the test condition. According to the module temperature T and the open circuit voltage V oc , short circuit current I sc and fill factor FF, and obtain the open circuit voltage V under test conditions oc , short circuit current I sc and fill factor FF;

[0010] According to the open circuit voltage V under each test condition oc , short circuit current I sc and fill factor FF, a solar cell IV relationship curve is fitted, and the maximum power point under the test conditions is obtained;

[0011] Obtaining a plurality of solar cell IV relationship curves and maximum power points under at least two test conditions;

[0012] Perform curve fitting on the maximum power points under at least two test conditions to obtain a maximum power point fitting curve.

[0013] Optionally, according to the module temperature T and the short-circuit current I sc The relationship between the short-circuit current I under the test condition is obtained. sc , where module temperature T and short-circuit current I sc The relationship is:

[0014]

[0015] Among them, I sc is the short-circuit current, T is the module temperature, I sc,1sum is the ideal short-circuit current, E g is the band gap energy, f c To collect points.

[0016] Optionally, based on the module temperature and open circuit voltage V oc The relationship between the open circuit voltage V under test conditions is obtained. oc , where module temperature T and open circuit voltage V oc The relationship is:

[0017]

[0018] Where T is the module temperature, V oc is the open circuit voltage, I sc is the short-circuit current, I o is the reverse saturation current.

[0019] Optionally, the filling factor FF under the test condition is obtained according to the relationship between the module temperature T and the filling factor FF, wherein the relationship between the module temperature T and the filling factor FF is:

[0020]

[0021] Among them, I sc is the short-circuit current, T is the module temperature, FF0 is the ideal fill factor, R s is the series resistance.

[0022] Optionally, the reference condition is light G = 1000 W / m 2 , module temperature T = 25 ° C and standard conditions of AM1.5.

[0023] Optionally, among the at least two test conditions, the temperature values ​​of at least some of the at least two test conditions increase in equal increments.

[0024] Optionally, the increment value ΔT of the temperature values ​​of at least two test conditions that increases in equal increments is any value between 3° C. and 7° C.

[0025] Optionally, among the at least two test conditions, the irradiance values ​​of at least some of the at least two test conditions increase in equal increments.

[0026] Optionally, in at least two test conditions, the irradiance values ​​of at least some of the at least two test conditions are incremented by equal values ​​and the increment value is 150 W / m 2 Up to 250W / m 2 Any value in .

[0027] Optionally, the photovoltaic cell is a Topcon cell.

[0028] Compared with the prior art, the method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions provided by the present invention achieves at least the following beneficial effects:

[0029] The method for predicting the working characteristics of photovoltaic cells under different light and temperature conditions provided in this embodiment is to obtain an irradiance of 200-1000W / m 2 A plurality of solar cell IV relationship curves and maximum power points under at least two test conditions with the module temperature in the range of 25°C-75°C are obtained, and then a maximum power point fitting curve is obtained to achieve maximum power point tracking.

[0030] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0031] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0033] Figure 1 The figure is a flow chart of a method for predicting working characteristics of a photovoltaic cell under different illumination and temperature conditions provided by an embodiment of the present invention;

[0034] Figure 2 The figure shows the working characteristic curve of the photovoltaic cell provided by the embodiment of the present invention under different test conditions;

[0035] Figure 3 Shown is a maximum power point distribution diagram of a photovoltaic cell provided by an embodiment of the present invention under multiple different test conditions;

[0036] Figure 4 Shown is a fitting curve diagram of the maximum power point of the photovoltaic cell provided by the embodiment of the present invention under multiple different test conditions. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0038] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0039] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0040] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0041] It is obvious to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Therefore, the present invention is intended to cover modifications and variations of the present invention that fall within the scope of the corresponding claims (technical solutions claimed for protection) and their equivalents. It should be noted that the implementation methods provided in the embodiments of the present invention can be combined with each other without contradiction.

[0042] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0043] As a safe, efficient and convenient new energy device, photovoltaic cells have developed rapidly in recent years. Correspondingly, the study of photovoltaic cell characteristics has also become an important topic. Among them, the maximum power of photovoltaic cells is one of the key points of photovoltaic cell characteristic research.

[0044] The most direct way to obtain the output characteristic curve of a photovoltaic cell is to measure it directly using an IV curve tester. However, the measured output characteristic curve is only the output characteristic curve under a specific temperature and sunlight intensity, and this curve cannot represent the output characteristic curve under other temperatures and sunlight intensities.

[0045] At present, the working parameters of mass-produced batteries are basically tested under standard test conditions (STC: 1kW / m2 irradiance, 25℃ module temperature and AM1.5 global spectrum). The parameters of solar cells such as short-circuit current, open-circuit voltage and fill factor will change with temperature and irradiance. During the use of photovoltaic panels, their working characteristics will change significantly with changes in light and temperature conditions. Therefore, the prediction of the working characteristics of photovoltaic cells is of great significance and is related to the utilization efficiency of photovoltaic power generation.

[0046] Therefore, studying the temperature dependence of solar cells and modules is very important for evaluating the actual output of solar cells and modules. The current single measurement standard for mass-produced cells and modules cannot clearly define the parameter changes of photovoltaic cells and modules under different temperatures and irradiances.

[0047] Figure 1 The figure is a flow chart of a method for predicting working characteristics of a photovoltaic cell under different illumination and temperature conditions provided by an embodiment of the present invention; Figure 2 The figure shows the working characteristic curve of the photovoltaic cell provided by the embodiment of the present invention under different test conditions. Figure 1 The embodiment of the present invention provides a method for predicting the working characteristics of a photovoltaic cell under different illumination and temperature conditions, comprising the following steps:

[0048] S01. Select a certain condition as a reference condition, measure the voltage and current data of the solar cell under the reference condition, and form an IV relationship curve of the solar cell under the reference condition;

[0049] S02, select light G = 200W / m 2 -1000W / m 2 Any condition within the range of module temperature T = 25°C-75°C is used as the test condition. According to the module temperature T and the open circuit voltage V oc , short circuit current I sc and fill factor FF, and obtain the open circuit voltage V under test conditions oc , short circuit current Isc and fill factor FF;

[0050] S03, according to the open circuit voltage V under each test condition oc , short circuit current I sc and fill factor FF, a solar cell IV relationship curve is fitted, and the maximum power point under the test conditions is obtained;

[0051] S04, obtaining a plurality of solar cell IV relationship curves and maximum power points under at least two test conditions;

[0052] S05. Perform curve fitting on the maximum power points under at least two test conditions to obtain a maximum power point fitting curve.

[0053] In S01 of this embodiment, a certain illumination temperature is selected as a reference condition, and the voltage and current data of the solar cell under the reference condition are measured to form an IV relationship curve of the solar cell under the reference condition. Then, the open circuit voltage V' under the reference condition can be directly read through the intersection of the IV relationship curve under the reference condition and the coordinate axis. oc , short circuit current I' sc , and then by the formula FF = (I m ×V m ) / (V' oc ×I' sc ), where I m is the current at maximum output power under this reference condition, V m is the voltage at maximum output power under the reference condition, and the fill factor FF' under the reference condition is calculated.

[0054] Because the light irradiance of the working environment of photovoltaic cells is generally 200W / m 2 -1000W / m 2 , the temperature is 25℃-75℃, therefore, in S02 of the embodiment, the light intensity G=200W / m 2 -1000W / m 2 Any condition within the range of module temperature T = 25℃-75℃ is used as the test condition. Such test conditions are more in line with the actual working environment conditions of photovoltaic cells. Under each test condition, according to the module temperature T and the open circuit voltage V oc , short circuit current I sc The relationship between the fill factor FF and the open circuit voltage V under the test conditions can be obtained. oc , short circuit current I scand fill factor FF; in S03 of the embodiment, the IV relationship curve of the solar cell under each test condition can be fitted, and the maximum power point under the test condition can be obtained. In this way, the IV relationship curve and the maximum power point of the solar cell under the test condition are also close to the working characteristics of the photovoltaic cell under the actual working environment conditions.

[0055] Among them, in S02, according to the module temperature T and the open circuit voltage V oc , short circuit current I sc and fill factor FF, and obtain the open circuit voltage V under test conditions oc , short circuit current I sc And the fill factor FF, specifically:

[0056] Module temperature T and short-circuit current I sc The relationship is:

[0057]

[0058] Module temperature T and open circuit voltage V oc The relationship is:

[0059]

[0060] The relationship between module temperature T and fill factor FF is:

[0061]

[0062] Among them, V oc is the open circuit voltage, I sc is the short-circuit current, T is the module temperature (unit: K), I o is the reverse saturation current, I sc,1sum is the ideal short-circuit current, E g is the band gap energy, f c is the collection fraction, FF0 is the ideal filling factor, R s is the series resistance; the reverse saturation current I o 、Ideal short-circuit current I sc,1sum , band gap energy E g , collect the scores f c , ideal fill factor FF0, series resistance R s These parameters are intrinsic parameters of solar cells.

[0063] The method for predicting the working characteristics of photovoltaic cells under different light and temperature conditions provided in this embodiment is to obtain an irradiance of 200-1000W / m 2Multiple solar cell IV relationship curves and at least two maximum power points under at least two test conditions with module temperature in the range of 25℃-75℃ are used to track the maximum power point and clarify the parameter changes of photovoltaic cells and modules under different temperatures and irradiances.

[0064] In some embodiments, the irradiance of the reference condition is 1000 W / m 2 , the module temperature is 25°C and AM1.5. It should be noted that as part of the photovoltaic cell production process, the components are measured under standard conditions (STC) of light irradiance 1000W / m2, mold temperature 25°C and AM1.5. This embodiment selects standard conditions as reference conditions, which can reduce the process of measuring the voltage and current data of the solar cell under the reference conditions and directly obtain the IV relationship curve of the solar cell under the reference conditions.

[0065] In some embodiments, in at least two test conditions, the temperature values ​​of at least some of the at least two test conditions are increased in equal increments. As a more specific solution in this embodiment, the light intensity G=200W / m 2 -1000W / m 2 At least two conditions within the range of module temperature T=25°C-75°C are used as test conditions, including 10 module temperatures T increasing in equal values, such as 25°C, 30°C, 35°C, ..., 65°C, 70°C.

[0066] In some embodiments, the increment value ΔT of the temperature values ​​of at least two test conditions that increases in equal increments is any value between 3° C. and 7° C.

[0067] In specific implementation, the incremental values ​​of the temperature values ​​of at least two test conditions that increase in equal amounts can be any incremental values ​​within the range of 3°C to 7°C, such as 3°C, 3.5°C, 4°C, 5°C, 6°C, etc.; the incremental values ​​of the temperature values ​​of at least two test conditions that increase in equal amounts can also be any value within the range of 3°C to 5°C, 4°C to 6°C, 6°C to 7°C, etc.

[0068] In some embodiments, in at least two test conditions, at least some of the at least two test conditions have an equal increase in light irradiance. As a more specific solution in this embodiment, light G = 200 W / m 2 -1000W / m 2 At least two conditions within the range of module temperature T = 25°C-75°C are used as test conditions, including 5 light irradiance G with equal value increase, such as 200W / m 2 , 400W / m 2 、600W / m 2 、800W / m 2 , 1000W / m2 .

[0069] In some embodiments, in at least two test conditions, the light irradiance values ​​of at least some of the at least two test conditions are incremented by equal values, and the increment value is 150 W / m 2 Up to 250W / m 2 Any value in .

[0070] In specific implementation, the incremental value of the light irradiance values ​​of at least two test conditions with equal increments can be 160W / m 2 、180W / m 2 、210W / m 2 、240W / m 2 , 250W / m 2 Any one in 150W / m 2 Up to 250W / m 2 The increment value within the range; the increment value of at least two test conditions with temperature values ​​increasing in equal increments can also be 150W / m 2 Up to 200W / m 2 、180W / m 2 Up to 200W / m 2 、220W / m 2 Up to 250W / m 2 Any value in the same range.

[0071] In some embodiments, the photovoltaic cell is a Topcon cell.

[0072] Experimental verification

[0073] Using a photovoltaic cell module consisting of 72 half-cell photovoltaic cells connected in series, the standard test conditions (1kW / m 2 Irradiance, 25°C temperature) is the reference condition, and the IV curve under the reference condition is obtained according to the IV curve under the reference condition;

[0074] Optionally, the reference condition is used as the first test condition, and the open circuit voltage V' under the reference condition can be directly read through the intersection of the IV relationship curve under this condition and the coordinate axis. oc =0.6950V, short circuit current I' sc =10.29A and the fill factor FF under this condition is calculated to be 84.06%.

[0075] Select the light G range to be 200W / m 2 Up to 1000kW / m 2 , and the module temperature T ranges from 25℃ to 75℃ as the test condition. According to the module temperature T and the open circuit voltage V ocThe relationship (1), module temperature T and short-circuit current I sc The relationship (2) and the relationship (3) between the module temperature T and the fill factor FF can be used to obtain the values ​​of the electrical performance parameters under at least two test conditions, as shown in the following table:

[0076]

[0077]

[0078]

[0079]

[0080] With light G = 200W / m 2 Taking the module temperature T=25° C. as the second test condition as an example, the calculation process for obtaining the values ​​of the electrical performance parameters under this test condition is as follows.

[0081] 1) According to the module temperature T and short-circuit current I sc The short-circuit current I under the second test condition can be obtained by using the relationship (1). sc , as follows:

[0082] First, the module temperature T and the short-circuit current I sc The relationship is:

[0083]

[0084] Substituting the specific parameters of the battery under reference conditions into the relation (1), the ideal short-circuit current I sc,1sum , band gap energy E g and collect the scores f c , where I sc,1sum =0.025T-5.3170, f c =0.45T-89.122, we get the equation Integrate both sides of this equation sc =0.0217*I sc *T+B, B is a constant;

[0085] Then, to I sc =0.0217*I sc * Substitute the module temperature T and short-circuit current I' under reference conditions into T+B sc , where I' sc =10.29A, T'=298.15K (25°C), and B=-56.28;

[0086] Finally, substitute the specific parameters of the ideal short-circuit current I of the battery under the second test condition into the relationship (1): sc,1sum , band gap energy E g and collect the scores f c At this time, I sc,1sum =0.0255T-5.1743, f c =0.455T-87.7632, we get the equation Substitute the module temperature T and constant B of this test condition into equation I sc =0.020*I sc *T+B, where T=298.15K (25°C), B=-56.28, thus obtaining the short-circuit current I under the test conditions sc =11.34A.

[0087] 2) According to the relationship between module temperature T and fill factor FF (3), the fill factor FF under the test conditions can be obtained as follows:

[0088] First, the module temperature T and the circuit voltage V oc The relationship is:

[0089]

[0090] Substitute the short-circuit current I' under reference conditions into equation (2) sc , i.e. I' sc = 10.29A, and the specific parameters of the battery reverse saturation current I o , where I o =0.8851T-262.2502, we get Integrate V on both sides of the equation oc =-0.25*V oc *T+C, C is a constant;

[0091] Then, to V oc =-0.25*V oc * Substitute the module temperature T and open circuit voltage V' under reference conditions into T+C oc , where V' oc =0.695V, T=298.15K (25°C), and C=62.397;

[0092] Finally, substitute the specific parameter reverse saturation current I of the battery under the second test condition into equation (2): o , where I o =0.5652T-159.1045, we get the equation Substituting the module temperature T and constant C of this test condition into the equation V oc =-0.301*V oc *T+C, where T=298.15K (25°C), C=62.397, thus obtaining the open circuit voltage V under the test conditions oc =0.6874V.

[0093] 3) According to the relationship between module temperature T and fill factor FF (3), the fill factor FF under the test conditions can be obtained as follows:

[0094] First, the relationship between module temperature T and fill factor FF is:

[0095]

[0096] Substitute the short-circuit current I' under reference conditions into equation (3) sc , Battery specific parameters reverse saturation current I o , ideal fill factor FF0 and series resistance R s , where I' sc =10.29A, I o =0.8851T-262.2502, FF0 = 85%, R s =0.015T-24.2490, we get Integrate both sides of the equation at the same time FF = -0.12*FF*T+D, where D is a constant;

[0097] Then, the module temperature T and the fill factor FF' under the reference condition are substituted into FF = -0.12*FF*T+D, where FF' = 84.06%, T = 298.15K (25°C), and D = 330.075 is obtained;

[0098] Finally, substitute the specific parameter reverse saturation current I of the battery under the second test condition into equation (2): o , ideal fill factor FF0 and series resistance R s , where I o =0.5652T-159.1045, FF0 = 85.5%, R s =0.020T-15.333, we get the equation Substituting the module temperature T and constant D of the test condition into the equation FF=-0.116*FF*T+D, where T=298.15K (25°C), D=30.9796, the fill factor FF under the test condition is obtained to be 84.37.

[0099] It can be seen that when the light G = 200W / m 2Under the second test condition where the module temperature T is 25°C, the electrical performance parameter value under this test condition can be obtained according to equations (1), (2) and (3), i.e., the short-circuit current I sc =11.392A, open circuit voltage V oc =0.575V and fill factor FF=87.05%, thus, the IV relationship curve of the solar cell under the test condition can be fitted, and the maximum power point Pm under the test condition is obtained to be 427.

[0100] Similarly, the electrical performance parameter values ​​under any test condition where the illumination G ranges from 200W / m2 to 1000kW / m2 and the module temperature T ranges from 25°C to 75°C can be obtained.

[0101] Figure 3 The figure shows the maximum power point distribution diagram of the photovoltaic cell provided by the embodiment of the present invention under different test conditions. Figure 4 Shown is a fitting curve diagram of the maximum power point of the photovoltaic cell provided by the embodiment of the present invention under different test conditions.

[0102] Each test condition can fit a solar cell IV relationship curve and obtain the maximum power point Pm under the test condition. Figure 2 , with light G as 1000kW / m 2 The module temperature T is 25°C and the light intensity G is 200kW / m 2 The module temperature T is 25°C and the light intensity G is 1000kW / m 2 And the module temperature T is 35°C. Taking these three test conditions as an example, it can be seen that each solar cell IV relationship curve corresponds to a maximum power point Pm, which are Pm1, Pm2 and Pm3 respectively.

[0103] Thus, a database of different temperature, irradiance conditions and maximum power point Pm is established, and this database is imported into the MPPT (Maximum Power Point Tracking) controller, see Figure 4 , curve fitting is performed on the maximum power point under all test conditions to obtain the maximum power point fitting curve.

[0104] During operation, the MPPT controller continuously detects the current and voltage changes of the photovoltaic cell to determine its output characteristic curve. In addition, the MPPT controller integrates specific algorithms such as the perturbation and observation method (P&O) or the conductance increment method (INC), which periodically apply perturbations to the working point of the photovoltaic cell and adjust the direction and amplitude of the perturbations according to the changes in output power and voltage to track the maximum power point.

[0105] The specific implementation process is as follows:

[0106] The working principle of the composite MPPT algorithm combined with the conventional algorithm is to first set the working point of the photovoltaic cell module near the maximum power point, and then use the ordinary algorithm for precise positioning, that is, to control the photovoltaic cell module to output the maximum power at the optimal ratio point of the working voltage and current in two stages.

[0107] The maximum power point of the photovoltaic cell module has a certain proportional relationship with the open circuit voltage and short circuit current. After the first step of control, the system obtains a reference value. During the first step of control, the data of the system's actual maximum power point is saved. The latter stage uses the perturbation observation method to achieve the final positioning, but the maximum power point obtained previously may fall within the range of local extreme points. At this time, the size of the data saved in the first step of control is compared to determine whether the power point is the global maximum power point. This method is easy to implement and the search speed is very fast.

[0108] Let's take a specific implementation process as an example to illustrate:

[0109] Under the initial working conditions of the photovoltaic cell assembly, the working temperature and irradiance are preferably set to 30℃ and 1000 irradiance to obtain the maximum power point output. However, in fact, the actual working temperature of the photovoltaic assembly changes in real time. When the working environment changes, such as the next working environment at a temperature of 30℃ and an irradiance of 800, the system queries the list database content and obtains the local maximum power point closest to the working environment at 25℃, 800 irradiance and 30℃, 1000 irradiance. At this time, the MPPT controller, on the one hand, adjusts the working state of the DC / DC converter (such as a boost or buck converter) to change the equivalent resistance to make it equal to the internal resistance of the photovoltaic cell, thereby achieving maximum power output; on the other hand, by changing the tilt angle of the photovoltaic assembly, the light receiving angle and light receiving area of ​​the assembly are changed to approach the local maximum power point under the current working environment.

[0110] In summary, the method for predicting the working characteristics of photovoltaic cells under different light and temperature conditions provided by the present invention achieves at least the following beneficial effects:

[0111] The method for predicting the working characteristics of photovoltaic cells under different light and temperature conditions provided in this embodiment is to obtain an irradiance of 200-1000W / m 2 A plurality of solar cell IV relationship curves and maximum power points under at least two test conditions with the module temperature in the range of 25°C-75°C are obtained, and then a maximum power point fitting curve is obtained to achieve maximum power point tracking.

[0112] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for predicting the working characteristics of photovoltaic cells under different light and temperature conditions. It is characterized in that The following steps are involved: Select a certain condition as a reference condition, measure the voltage and current data of the solar cell under the reference condition, and form an IV relationship curve of the solar cell under the reference condition; Select light G = 200W / m 2 -1000W / m 2 Any condition within the range of module temperature T = 25°C-75°C is used as the test condition. According to the module temperature T and the open circuit voltage V oc , short circuit current I sc and fill factor FF, and obtain the open circuit voltage V under test conditions oc , short circuit current I sc and fill factor FF; According to the open circuit voltage V under each test condition oc , short circuit current I sc and fill factor FF, a solar cell IV relationship curve is fitted, and the maximum power point under the test conditions is obtained; Obtaining a plurality of solar cell IV relationship curves and maximum power points under at least two test conditions; Perform curve fitting on the maximum power points under at least two test conditions to obtain a maximum power point fitting curve.

2. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 1, It is characterized in that According to the module temperature T and short-circuit current I sc The relationship between the short-circuit current I under the test condition is obtained. sc , where module temperature T and short-circuit current I sc The relationship is: Among them, I sc is the short-circuit current, T is the module temperature, I sc,1sum is the ideal short-circuit current, E g is the band gap energy, f c To collect points.

3. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 2, It is characterized in that According to the module temperature and open circuit voltage V oc The relationship between the open circuit voltage V under test conditions is obtained. oc , where module temperature T and open circuit voltage V oc The relationship is: Where T is the module temperature, V oc is the open circuit voltage, I sc is the short-circuit current, I o is the reverse saturation current.

4. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 2, It is characterized in that According to the relationship between the module temperature T and the filling factor FF, the filling factor FF under the test conditions is obtained, wherein the relationship between the module temperature T and the filling factor FF is: Among them, I sc is the short-circuit current, T is the module temperature, FF is 0 is the ideal fill factor, R s is the series resistance.

5. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 1, It is characterized in that The reference condition is light G = 1000W / m 2 , module temperature T = 25 ° C and standard conditions of AM1.

5.

6. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 1, It is characterized in that Among the at least two test conditions, the temperature values ​​of at least some of the at least two test conditions increase in equal increments.

7. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 4, It is characterized in that The temperature values ​​of at least two test conditions increase in equal increments by an increment value ΔT of any value between 3°C and 7°C.

8. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 1, It is characterized in that Among the at least two test conditions, the irradiance values ​​of at least some of the at least two test conditions increase in equal increments.

9. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 6, It is characterized in that In at least two test conditions, the irradiance values ​​of at least some of the at least two test conditions are equally increased by an increment of 150 W / m 2 Up to 250W / m 2 Any value in .

10. The method for predicting the working characteristics of a photovoltaic cell under different light and temperature conditions as claimed in claim 1, It is characterized in that The photovoltaic cell is a Topcon cell.

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