KR20020085185A - Photovoltaic characteristic tracer and the method - Google Patents

Abstract

PURPOSE: Provided are a tracer for property of solar battery capable of maximizing stability and utility of solar energy by providing more correct information about solar battery to a user. CONSTITUTION: The tracer for analyzing the property of solar battery by extracting open voltage, short current, optimal voltage, and optimal current from output of the solar battery panel, comprises a solar battery panel(10) for collecting sunlight and outputting voltage and current values; a thermometer for measuring a surface temperature of the panel; a solar radiation meter(20) for measuring an intensity of radiation radiated to the panel; an amplifier(30) for amplifying fine output voltage and output current values resulting from the panel, thermometer, and solar radiation meter into predetermined level of analog value; an analog/digital converter(A/D converter) for converting the analog value(signal) to digital signal; a DC load(40), in which current load varies from 0 to ∞, so as to extract open voltage and short current of solar battery; and a computer(50) for controlling the DC load and processing the digital signal passed through the A/D converter.

Description

Photovoltaic characteristic tracer and the method

The present invention relates to a solar cell tracking device and a method thereof, and more particularly, to input voltage and current from a solar cell panel, data from a solar meter and a thermometer through a serial port of a computer, and then through a program of a solar cell tracking device. By deriving the characteristic parameter, it is possible to grasp the characteristics of the solar cell.

Due to the rapid spread of solar cell power system using solar cell due to strong demand for securing and developing alternative energy, the demand of solar cell characteristic tracking device that checks the rough characteristics of installed solar cell has been year after year. The trend is increasing.

In general, the basic configuration of the solar cell characteristic tracking device (hereinafter referred to as VI tracer) is divided into a variable resistor portion connecting the output terminal portion of the solar cell and a portion for inputting data from a solar radiation meter and a thermometer.

There is a slight difference between the companies that produce them, but it is divided into a system method and an integrated display part through an interface with a notebook computer.

The basic data required from the solar cell requires the open circuit voltage (Voc) and the short circuit current (Isc) of the solar cell, and the voltage (Vop) and the current (Iop) of the maximum output power point. Clicking the button to start the operation on the screen automatically outputs the necessary data on the display.

In general, the operation sequence of the solar cell characteristic tracking device according to the prior art first connects the output terminal of the solar cell and the variable resistance portion of the solar cell characteristic tracking device, and then the output terminal of the solar radiation meter and thermometer and the solar cell characteristic tracking device. The connection step of the solar cell characteristic tracking device connecting the sensor input part, the load variation step of the variable resistor which changes the variable resistor connected to the solar cell from infinity to 0Ω, the amount of change of the solar cell output voltage over time, the solar cell The short-circuit current (Isc) is a time input of the amount of change of the output current, the amount of insolation at the time from the solar meter, and the temperature at the time from the thermometer, and the value of the output current when the output voltage value is 0. When the output current value is 0, the output voltage value is determined as an open voltage (Voc). An output value calculation step of judging the voltage and the current value at the time when the maximum power value is calculated from the product of the output current values as the optimum voltage (Vop) and the optimum current (Iop), and the output voltage value according to the time change as the x-axis, Set the output current value on the y-axis to display the voltage-current characteristic curve, calculate the calculated short-circuit current (Isc), open voltage (Voc), optimum voltage (Vop), and optimum current

(Iop) is displayed, and it is composed of a display step of calculating and displaying the characteristic value (FF: Fill factor) of the solar cell shown in Equation 1 (see page), and displaying the input solar radiation value and the surface temperature of the solar cell. .

However, the output of the solar cell characteristic tracking device according to the prior art as described above is open voltage (Voc), short-circuit current (Isc), optimal voltage (Vop), optimal current (Iop), characteristic value of the solar cell (FF) It is possible to confirm the output characteristics of the schematic solar cell, but it is impossible to reconstruct the detailed characteristic equation.

In addition, there is no information displayed other than the output characteristics at the time of measurement using a solar cell tracer (VI tracer), and if the weather conditions change, another measurement is inevitable.

Therefore, even though the detailed parameters of the characteristic equation are essential for the characteristic analysis through the simulation of the installed solar cells, the VI tracer of the prior art does not calculate the detailed parameters, resulting in more information on the installed solar cells. Provision is required.

The present invention has been made to solve the problems as described above, by deriving the characteristic equation parameters of the solar cell that could not be implemented in the conventional system to provide a user with more convenient and accurate solar cell information, The purpose of the present invention is to provide a solar cell characteristic tracking device and a method for maximizing utilization efficiency and stability.

The solar cell characteristic tracking method and apparatus according to the present invention for achieving the above object is to extract the open voltage, short circuit current, optimal voltage, and the optimum current from the output of the solar panel to understand the characteristics of the solar cell A solar cell characteristic tracking device comprising: a solar cell panel for condensing sunlight and outputting voltage and current values, a thermometer for measuring the surface temperature of the solar cell panel, and an amount of light irradiated on the solar panel A solar radiation meter, an amplifier for amplifying the micro output voltage and output current values from the solar panel and the photometer into a constant analog value, and converting the analog values of the amplifier into digital values for input into a program Connected to an analog / digital converter (A / D converter) and an output terminal of the solar cell panel before opening of the solar cell. And controlling the short-circuit and the electronic load so that the current to vary the load to 0 ~ ∞Ω to extract the electronic load, and is characterized by consisting of a computer to process a digital signal via an analog / digital converter.

1 is a detailed view showing the configuration of a solar cell characteristic tracking device according to the present invention.

Figure 2 is a block diagram showing a signal processing procedure of the solar cell characteristic tracking device according to the present invention.

Figure 3 is a graphical user interface of the solar cell characteristic tracking device according to the present invention

Flow chart showing the processing procedure (GUI: graphic user interface).

4 is a flowchart illustrating a process of determining a short circuit current of a solar cell characteristic tracking device according to the present invention;

5 is a flowchart illustrating a process of determining an open voltage of a solar cell characteristic tracking device according to the present invention;

Figure 6 is a flowchart showing the flow of the voltage / current characteristic equation of the solar cell characteristic tracking device according to the present invention.

Explanation of symbols on the main parts of the drawing

10, 11: solar panel 12: output current

13 output voltage 20 photometer

21: solar radiation 22: temperature

30: amplifier 31: solar radiation voltage amplification

32: temperature voltage amplification 33: current terminal

34: voltage terminal 40, 41: electronic load device

50: computer 51: solar cell tracking device program

52: Calculation of parameters 53: Control of electronic load device

60: AD converter 100: determination of short circuit current

200: determination of open voltage 300: determination of characteristic parameters

360: Determination of temperature-dependent parameters

370: Determination of series / parallel internal parasitic resistance 400: Display of parameters

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

1 is a detailed diagram showing the configuration of a solar cell characteristic tracking device according to the present invention, FIG. 2 is a block diagram showing a signal processing procedure of the solar cell characteristic tracking device according to the present invention, and FIG. User interface of solar cell tracking device

(GUI: Graphic User Interface) is a flowchart showing the processing procedure, Figure 4 is a flowchart showing a process of determining the short-circuit current of the solar cell characteristic tracking device according to the present invention, Figure 5 is according to the present invention FIG. 6 is a flowchart illustrating a process of determining an open voltage of a solar cell characteristic tracking device, and FIG. 6 is a flowchart illustrating an extraction process of a voltage / current characteristic equation of the solar cell characteristic tracking device according to the present invention.

1 and 2, the basic configuration of the solar cell characteristic tracking device according to the present invention is largely divided into a hardware configuration and a software configuration.

First, as shown in FIG. 1, a hardware configuration tracking device according to the present invention includes a solar cell panel 10 for collecting solar light and outputting voltage and current values according to the present invention, and the solar cell panel ( 10) Thermometer 19 for measuring the temperature of the surface, the solar radiation meter 20 for measuring the amount of solar light, the fine from the solar panel 10, the solar radiation meter 20, the thermometer 19 An amplifier 30 that amplifies the output voltage and output current values to analog values of a predetermined level, and an analog / digital converter (A / D converter) for converting the analog values of the amplifier 30 into digital values for input into a program. 60, an electronic load device 40 connected to an output terminal of the solar cell panel 10 to vary the load from 0 to ∞ Ω so as to extract an open voltage and a short circuit current of the solar cell, and the electron Control the load device 40, and It characterized by configured by the computer 50 to calculate a digital signal subjected to digital converter 60 value.

Here, the current and voltage from the output terminal of the solar panel 10 is converted into the allowable voltage range in the amplifier 30 to convert the analog signal into a digital signal through the current terminal CT and the voltage terminal PT. Data is input to the computer 50 via the A / D converter 60.

In addition, the micro-voltage related to the temperature and the solar radiation from the thermometer 19 and the solar radiation meter 20 is also amplified by the amplifier (OP-amp) 30, a computer (A / D converter 60) 50) data is input.

In addition, the resistance of the electronic load device 40 connected to the output terminal of the solar cell panel 10 is an interface between the general purpose interface bus (GPIB) terminal (not shown) of the electronic load device and the serial port of the computer. It is automatically adjusted by user's operation by using.

That is, when a user instructs a command related to short-circuit current, open voltage, and extraction of characteristic equations through a computer, the electronic load device according to the program (omitted) related thereto.

The resistance of 40 can be continuously varied from zero to infinity, or can be adjusted to any particular resistance value.

In addition, the configuration of the software is a signal processing procedure as shown in FIG. 2, and the analog voltage 13 and the current 12 values from the output terminal of the solar panel 11 are the voltage terminals.

(PT) 34 and current terminal (CT) 33 are converted to the appropriate analog voltage value, and the analog microvoltage value of the solar radiation amount 21 and the temperature 22 of the thermometer 19 and the solar radiation meter 20 is an amplifier. (OPamp) 31 and 32 are converted into appropriate analog voltage values.

Here, the changed appropriate voltage values are converted into a digital signal through the analog-to-digital converter 60 so as to enable digital signal processing in a computer and inputted into a program.

In addition, the operation of the electronic load device 41 is operated through an interface between the serial port of the computer and the interface bus (GPIB) terminal of the electronic load device 41.

Next, a Graphic User Interface (GUI) program is configured for communication between the user and the program.

The configured graphical user interface program can be represented by a block diagram as shown in FIG.

That is, the first step 100 to extract the short-circuit current (Isc) divided into three stages, the second step 200 to extract the open voltage (Voc), and the second to extract the characteristic parameters of the installed solar cell It is divided into three steps (300), and finally consists of a display unit 400 for displaying a value within the tolerance set by the user.

Here, the extracted short-circuit current and the open-circuit value are used as they are in extracting the detailed parameters.

In more detail, the first step is to extract the short-circuit current (Isc) (100), the process of extracting the short-circuit current (Isc) of the installed solar cell is represented as shown in FIG.

Here, when the extraction of the short-circuit current through the graphical user interface (GUI) command 110, the resistance value of the electronic load device is automatically set to 0kΩ (120). Therefore, the output current of the solar cell becomes a short-circuit current due to the set resistance value, the short-circuit current value and the amount of insolation are input into the program 130, and the amount of insolation 1.0kW / It is possible to extract the short circuit current value in m 2.

In addition, the second step is to extract the open voltage (Voc) (200), the process of extracting the open voltage (Voc) of the installed solar cell is represented as shown in FIG.

Here, when the extraction of the open voltage through the graphical user interface command 210, the resistance value of the electronic load device 40 is automatically set to ∞ 220. Therefore, the output voltage of the solar cell becomes an open voltage due to the set resistance value, and the output voltage value, the solar radiation at that time, and the surface temperature of the solar cell are input 230 into the program.

Then, from the input data, the open voltage and the amount of insolation are determined to 1.0 kW / m 2 and the open voltage 240 at that time, and the value of the open voltage at 1.0 kW / m 2 and the solar cell's surface temperature of 25 ° C. is final. 250 is extracted.

In addition, the third step is to extract the detailed parameters of the voltage-current characteristic equation (300), which is one of the greatest features of the system of the present invention is a part that does not exist in the conventional system.

The detailed characteristic equation of the solar cell can be explained through Equations 2 and 3, and the relational expression including the series and parallel internal parasitic resistances Rs and Rsh of the solar cell is expressed as Equation 4.

Equation 2 is a voltage-current characteristic equation of an ideal solar cell, which is called a representative expression of the solar cell, Equation 3 is a formula representing only the saturation current (Ios) of the parameters of the voltage-current characteristic equation of the solar cell, Equation 4 is a solar cell The most realistic equation considering the internal parasitic resistance in the voltage-current characteristic equation of.

The designed high-performance tracking device combines the temperature dependence parameter A and the series and parallel internal resistances Rs and Rsh in equations 3 and 4. This process can be described with reference to FIG.

That is, when the command 310 is given in the mode for the purpose of extracting the detailed parameter of the voltage and current characteristic equation, the series and parallel relationship between the installed solar cells (Si, Ge, GaAs, etc.), and the solar panel are finally obtained. The parameter input step 320 of inputting an allowable range of values is performed.

At the same time as the input value is determined in the input step, the program issues a command 330 to the electronic load device to change the electronic load device from ∞ ms to 0 ms.

Here, the change type and time of the resistance are operated in accordance with the command value programmed in the computer.

After the adjustment step 330 of the electronic load device, the amount of insolation, temperature, voltage, and current from the A / D converter is input, and a start time, an end time, and a data sampling time are automatically connected to each other. Signal processing.

Next, the signals passed through the input step calculate 350 the fill factor of the solar cell through a predetermined program and move to the routine 360 to extract the temperature dependency parameter A.

Next, in the routine 360 for extracting the temperature dependence parameter A, the approximate value of A (about 9.0e-2) is inputted into Equation 2 361, and the current value is 0 and the open voltage (calculated) is calculated. Voc-calculation) is calculated 362.

Here, the value of the temperature dependence parameter A is about 9.0e-2, which is a value obtained by inverting a solar cell having an opening voltage of 20 volts and a short circuit current of 3 A of the polysilicon of the parent company, and this value is an absolute value of the temperature dependency parameter. Is not.

In other words, the value of A is extracted by comparing the calculated value with the measured value and changing the value of A slightly by comparing the value again when the value exceeds the tolerance range.

After extraction of the temperature dependency parameter A, the series and parallel internal parasitic resistances

Step (370) of extracting (Rs, Rsh) is performed, and the values of the approximate series internal parasitic resistance (Rs) and the parallel internal parasitic resistance (Rsh) are input into Equation 4 in the same manner as the extraction of the A value. As a result, the solar cell characteristic value is calculated by calculation.

Here, when the calculated value and the measured value are compared, the series internal parasitic resistance (Rs) and the parallel internal parasitic resistance (Rsh) within the allowable range are extracted through the micro change.

Finally, the characteristic parameter of the solar cell is derived through the display step 400 by the method of tracking the characteristics of the solar cell as described above, so that the characteristics of the solar cell can be accurately determined.

Hereinafter, a brief description of the symbols used in the solar cell characteristic tracking device according to the present invention and the relations used are shown.

I = current through load [A] Isc = short circuit current [A]

Ios = saturation current [A] s = solar radiation [kW / m2]

q = amount of charge (1.6e-19 [C]) k = Boltzmann constant (1.38e-23 [J / K])

T = PN junction temperature [K], t [° C] n = junction constant

A = temperature constant parameter

Eg = energy gap [eV] V = solar cell voltage [Volt]

Voc = open circuit voltage of the solar cell [Volt]

P = output power of solar cell [W] Vop = optimal voltage of solar cell [Volt]

Varray-op = Optimal Voltage of Solar Panel Array [Volt]

Rs = series parasitic resistance [Ω]

Rsh = shunt parasitic resistance [Ω]

: Digital signal of solar radiation : Digital signal of surface temperature

: Digital signal of output current : Digital signal of output voltage

: Digital control signal of electronic load device

Relationship (1)

Relationship (2)

Relationship (3)

Relationship (4)

As described above, the solar cell characteristic tracking device according to the present invention can extract the parameters of a detailed voltage and current characteristic equation that cannot be extracted from the conventional solar cell tracer (VI tracer). It is possible to precisely calculate and verify the output of the output, to easily obtain the parameters to be applied to the simulation, to more accurately determine the output rating of the installed system, and to obtain basic data for calculating and improving the output efficiency. It can be utilized more easily, and the effect is that the system can be designed more economically.

Claims (5)

In the solar cell characteristic tracking device which can grasp the characteristics of the solar cell by extracting the open voltage, the short-circuit current, the optimum voltage, and the optimum current from the output of the solar panel, A solar panel for condensing sunlight and outputting voltage and current values accordingly; A thermometer for measuring a surface temperature of the solar cell panel; An insolation meter for measuring an amount of light injected into the solar cell panel; An amplifier for amplifying the fine output voltage and output current values from the solar panel, the thermometer, and the solar radiation meter to a constant analog value; An analog / digital converter (A / D converter) for converting the analog signal of the amplifier into a digital signal for input into a program; An electronic load device connected to an output terminal of the solar cell panel to vary a load from 0 to ∞ Ω to extract an open voltage and a short circuit current of the solar cell; And a computer configured to control the electronic load device and process digital signal values passed through an analog-to-digital converter. In the method to extract the open voltage and short-circuit current, the optimum voltage and the optimum current from the output of the solar panel to determine the characteristics of the solar cell, A first step of extracting a rated short-circuit current (Isc-insolation amount 1.0kW / m 2, surface temperature of 25 ° C.) by inputting the amount of insolation and current output from the solar cell panel; After the first step, the second step of extracting the rated open-circuit voltage (Voc-insolation amount 1.0kW / ㎡, surface temperature 25 ℃) by inputting the temperature and solar radiation of the solar panel, and the open voltage (Voc) value at that time Wow; And a third step of detecting the temperature dependency parameter A and the internal series and parallel parasitic resistances (Rs, Rsh) through a comparison loop with the measured values after the second step. The method of claim 2, The first step includes: controlling the electronic load device to command extraction of a short circuit current through a graphical user interface (GUI) program, and automatically setting the resistance of the electronic load device to 0? By the extract command of the short circuit current; A data input step of inputting a data value of a solar radiation amount and a current data value of the solar panel when the resistance of the electronic load device is 0? Calculating a short circuit current based on the amount of solar radiation inputted through the data input step and a current data value; Solar cell characteristic tracking method comprising the step of determining the result value to determine whether the value calculated in the step is valid for the result value. The method of claim 2, The second step includes: an electronic load device control step of automatically setting the resistance of the electronic load device to ∞? A data input step of inputting data of a solar radiation meter, a thermometer, and a voltage value of the solar panel when the resistance of the electronic load device is ∞? A first open voltage calculation step of calculating an open voltage based on the input data value as a function value related to voltage and insolation at the temperature of the thermometer; A second open voltage calculation step of calculating an open circuit voltage as a function value related to a voltage and a temperature at 25 ° C. after the first open voltage calculation step; And determining whether the value calculated in the second open voltage calculation step is valid for the result value. The method of claim 2, The third step includes: commanding extraction of detailed parameters of a voltage-current characteristic equation through the graphical user interface; Inputting the type of solar cell installed after the step, the solar cell series-parallel relationship of the solar panel, and the allowable range of the result values; Giving a command to change the electronic load device from ∞Ω to 0Ω or from 0Ω to ∞Ω after the step; Inputting data of solar radiation and temperature, current and voltage after the step; Calculating a solar cell fill factor based on the input data value; Calculating an open-circuit voltage by inputting an approximation value of the temperature dependence parameter A after calculating the solar cell fill factor, and finding the temperature dependence parameter through the comparison loop between the calculated value and the measured value; After determining the temperature dependency parameter A, input the approximate series internal parasitic resistance and the parallel internal parasitic resistance value to calculate the fill factor of the solar cell, and compare the calculated value and the measured value with the series internal parasitic resistance through a comparison loop. Finding an internal parasitic resistance; And determining whether the value calculated in the step of finding the series internal parasitic resistance and the parallel internal parasitic resistance is valid for the resultant value.