JPS5957174A - Method and apparatus for measuring output characteristic of solar battery - Google Patents

Abstract

PURPOSE:To achieve a quick measurement of output characteristic with limited error by selecting voltage and current ranges in the measuring system by performing a specified preliminary measurement to choose the optimum measuring range accurately for a short time. CONSTITUTION:When with voltage and current ranges set at max., voltage the same as that on the side of the cathode of an auxiliary power source 6 for forced short-circuiting is applied to a gate with a gate voltage control mechanism 4 to turn OFF an FET, the output terminal of a solar battery to be measured connected between terminals 7 and 9 is opened. Consequently, a fine current for forced opening in the opposite direction of the output current flows to the solar battery through a constant current source 5. At this point, when the voltage across output terminals of the solar battery is read with a voltage detector 10, the max. range voltage based on the open voltage is given irrelevant to internal resistance of the solar battery. Likewise, the max. range current is selected based on the short-circuit current. Thus, a quick measurement of the output characteristic of the battery can be performed with limited errors depending on the selection of the optimum range determined accurately for a short time by this preliminary measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring output characteristics of a solar cell.

A solar cell used in a solar power generation system is constructed by connecting a large number of C double-panel type solar cell units in series or in parallel in order to obtain a large output. In order to obtain power efficiently, it is necessary to know the output characteristics of the solar cells, and for this reason, we measure the relationship between the output voltage and output current of the solar cells under actual sunlight irradiation. things are being done. 1. By the way, when measuring the output characteristics of solar cells, it is normally required that the measurement error be within 100.5%, and solar cells have various different output characteristics depending on their configuration. , it is necessary to provide a large number of measurement ranges in the measurement system.

Conventionally, the measurer estimates the output characteristics of the solar cell to be measured in advance by intuition, selects all measurement ranges of the measurement system based on that estimate, and performs two measurements, or the conventional measurement system (in the second case, Since it is not possible to accurately measure the open circuit voltage and short circuit current sound because errors caused by the internal resistance of the thick battery cannot be removed, preliminary measurements were made by setting the measurement range of the measurement system to the maximum range in advance. The approximate values of the open circuit voltage and short circuit current of the solar cell are measured, and the approximate values of the open circuit voltage and short circuit current, which cannot actually be measured, are obtained by software calculation using a computer or the like based on these nearby values. The output characteristics of solar cells are measured by methods such as selecting a measurement range based on the approximate values obtained and then measuring the output characteristics again.

However, in the former method, the selection of the measurement range is quite rough, and the appropriate measurement range cannot necessarily be selected. must be selected,
Alternatively, a measurement range that is too small may be selected by mistake, and in this case, measurement cannot be performed. On the other hand, in the latter method, software calculations using a computer or the like must be performed to obtain approximate values of the open circuit current ratio and short-circuit current, which requires considerable effort and requires a complicated configuration of the measurement system.

The present invention has been made based on the above circumstances, and its purpose is to be able to reliably select the optimal measurement range for the solar cell to be measured in a short time, and to quickly perform measurements with small errors. The object of the present invention is to provide a method for measuring the output characteristics of a solar pond.

Another object of the present invention is to provide a solar cell output characteristic measuring device that can reliably accomplish the method of the present invention.

The present invention will be specifically explained below.

In one example of the method of the present invention, the solar cell to be measured is irradiated with sunlight to generate an electromotive force,
First, preliminary measurements are performed to measure approximate values of the open-circuit voltage and short-circuit current of the solar cell. That is, first, the output terminals of the solar cell are opened, and then, for example, a small current for forced opening from a constant current source is passed through the solar cell in the opposite direction to the direction in which the output current flows. The voltage between the output terminals of the battery is measured in advance with, for example, a voltmeter (two voltmeters) connected between the output terminals of the solar cell at its maximum range to obtain an approximate value of the open-circuit voltage.

Next, an ammeter is connected between the output terminals of the solar cell, the output terminals are short-circuited, and an output current is caused to flow, and a forced short-circuit current is applied to the solar cell in the direction in which the output current flows, the opening direction, and the direction in which the output current flows. The current flowing between the output terminals of the solar cell at that time is measured using the ammeter at its maximum range to obtain the approximate value of the short circuit current m.

Then, based on the approximate values of the open circuit voltage and short circuit current obtained as above, a voltage range and a current range that have the maximum level as these approximate values are selected, and the voltage range and current range that have been selected are also Next, connect a load between the output terminals of the solar cell, change the resistance value of this load from, for example, infinity to zero, and calculate the voltage between the output terminals and the current flowing between the output terminals corresponding to the resistance value. is measured, thereby obtaining the output characteristics of the solar cell.

According to the method described above, in preliminary measurements, the output terminals of the solar cell are opened, and then a minute current for forced opening is passed through the solar cell in the opposite direction to the direction in which the output current flows. Since the open-circuit voltage is measured, errors caused by the internal resistance of the solar cell are canceled out, and a value slightly larger than the actual open-circuit voltage is measured as an approximate value, so this approximate value is used as the maximum level. By selecting the voltage range for
Then, in addition to short-circuiting the output terminals of the solar cell and flowing an output current, a forced short-circuit current 7 is also flowed in the same direction as this output current to measure the short-circuit current.
Errors caused by the internal resistance of the solar cell are canceled out, and the approximate value measured is slightly larger than the actual short-circuit current, so by selecting the current range that takes this approximate value Z to its maximum level , the value of the actual short-circuit current can be ensured within that range (= the optimal current range).And since such a preliminary measurement can be mechanically performed in a short time ζ1, it is possible to The optimum measurement range can be selected in a short time.In this way, the preliminary measurement can be carried out in a short time and reliably to make the most accurate measurement of C, so that the output characteristics of the solar cell can be measured without error. It can be made small and can be carried out in five steps.

Next, an example of a suitable device for carrying out the present invention will be described.

In one example of the device of the present invention, as shown in FIG.
ET J and Hanako. )1 self-bias circuit 2 to source S
FE by connecting a large number of the pg'ri in parallel.
'l' parallel circuit 3 is formed, and on the gate G side of each F M 'I' 1 of this B''ET parallel circuit 3, there is a gate voltage control mechanism 4 that controls the voltage supplied to the gate G side.
The drain D (ljl≦-) of each 111ET1 of the IT parallel circuit 3 is connected to the constant current source 5 that supplies a small constant current to the drain D side, and the FkA' of each F of the parallel circuit 3 is connected.
h, on the source S side of T1, there is a cathode of a forced short circuit auxiliary power source (hereinafter simply referred to as "auxiliary power source") 6 which supplies a current for forced short circuit in the same direction as the source current Is through a self-bias circuit 2. one external connection terminal 772 is connected to the drain D side of each FETI in the FET parallel circuit 3, and
On the source S side of each 1"E'r1 of the E T parallel circuit 3,
A current detector 8 is connected via the auxiliary power supply 6, and the other external connection terminal 9 of the current detector 8C is connected,
A voltage detector 10 is connected between the one external connection terminal 7 and the other external connection terminal 9, and both the voltage detector 10 and the current detector 8 are connected to a voltage/current measuring mechanism 11. 12 is a voltage polarity detector connected between the external connection terminals 7 and 9, which detects when the polarity of the voltage between the external connection terminals 7 and 9 changes, and uses this detection signal to detect the change with a slight delay. F by gate voltage control mechanism 4
This is to stop the voltage supply to the gate G of each FETx in the ET parallel circuit 3. The anode side of the auxiliary power source 6 is held at ground potential, that is, zero potential.

The voltage/current measuring mechanism 11 is composed of, for example, a voltage range switching mechanism, a current range switching mechanism, and an automatic recording/reading mechanism that automatically reads the detected voltage and detected current.

The self-biasing circuit 2 having each of the ETIs divided into two parts includes, for example, a series circuit of a bias resistor 21 and an auxiliary bias resistor 22, and a circuit connected in parallel to the bias resistor 21.
! It is composed of a large number of diodes 23 connected in series so as to be in the forward direction with respect to the ETI source current Is.

According to the above configuration, measurement (= when the solar cell is connected between the external connection terminals 7 and 9 and the solar cell is irradiated with sunlight and an electromotive force is generated, the voltage The range switching mechanism and the current range switching mechanism set the voltage range and current range to the maximum range in advance, and the gate voltage control mechanism 4 sets the gate voltage of each FWTt of 1, 1E Fi + parallel circuit 3 to the auxiliary power source. Each F lu T 1 is set to the same voltage as the cathode side of 6.
When the output terminals of the solar cell are placed in an OFF state, the output terminals of the solar cell become in an open state, and a small current for forced opening flows through the solar cell from the constant current source 5 in the opposite direction to the output current. At this time, the voltage between the output terminals of the solar cell is measured by the pressure detector 10.
The voltage/current measuring mechanism 11 reads the voltage via the voltage/current measuring mechanism 11, and the voltage range switching mechanism switches the voltage range to the voltage range that makes the voltage value the maximum level.

Then, when the gate voltage applied to the gate G of each I''ETI of the FET parallel circuit 3 is increased by the gate pressure control mechanism 4, for example, in a stepwise manner, the source current is increases as the gate voltage increases. At the same time, the drain′
The voltage decreases, but since the source voltage is made negative by the auxiliary power supply 6, the source current is continues to flow even if the drain voltage exceeds zero and becomes negative, so the voltage polarity detector 12 detects When it is detected that the drain voltage has exceeded zero and the polarity has changed, the current flowing between the output terminals of the solar cell is read by the voltage/current measuring mechanism 11 via the current detector 8, and the current is read by the current range switching mechanism. Current range (switch between two) with that current value as the maximum level.

After completing the selection of the voltage range and current range in this way (=, again by the gate voltage control mechanism 4 i) 1! ”
The gate voltage applied to the gate G of each FET 1 of the 12T parallel circuit 3 is set to the same voltage as the cathode side of the auxiliary power supply 6, and each 1'
With all of ET1 turned off, measurement of the actual output characteristics is started from the open circuit voltage of the solar cell, that is, the maximum value of the output voltage of the solar cell. The value of the open circuit voltage of this solar cell is determined when the portion of the forced open minute current from the constant current source 5 that flows through the solar cell becomes zero, that is, when the current value detected by the current detector 8 becomes zero. When (- becomes equal to the voltage value detected by the voltage detector 10.

Then, the gate voltage control mechanism 4 gradually increases the voltage applied to the gate of each F1t'lJ of the FET parallel circuit 3 in, for example, a stepwise manner. 10 and ``The voltage/current measurement mechanism 11 detects the values of the detected voltage and detected current in the current detector 8.
I read it and recorded it. That is, when the gate voltage is increased by one step, the source current Is increases, and this increase in source current Is causes the drain voltage to drop.
So to speak, if you increase the gate voltage by one step)'kT
The resistance value of the parallel circuit 3 gradually decreases, so the measured value recorded at each step of the gate voltage is the output when the resistance value of the load connected between the output terminals of the solar cell is changed from infinity to zero. Corresponds to the characteristics.

When the gate voltage becomes high (and the drain voltage becomes zero, the voltage between the output terminals of the solar cell also becomes zero, and the current value detected by the current detector 8 at this time is equal to the actual short-circuit current of the solar cell). equals the value.

In this way, according to the device with the above configuration, the open circuit voltage of the solar cell can be measured in a state where no current is flowing through the solar cell, so it is possible to obtain a reliable value regardless of the internal resistance of the solar cell. Since the short circuit current can be measured with the voltage between the output terminals of the solar cell completely set to 1 zero, a reliable value can be obtained regardless of the internal resistance of the solar cell.Therefore, in preliminary measurements, Even when measuring open circuit voltage and short circuit current at the maximum range, the approximate values obtained are highly accurate. .In actual measurement of output characteristics under an appropriate measurement range, the values range from the open circuit voltage value when the solar cell is completely open to the short circuit current value when the solar cell is completely short-circuited. It is possible to reliably measure voltage and current characteristics.

As described above, by controlling the gate voltage so that the voltage gradually decreases from the high voltage side, the current flowing through the FET parallel circuit 3 increases gradually from a small value in the FgT parallel circuit. 3 is activated, there is no risk of rush current flowing through each FETI, and the service life of each 1'ETI can be extended.

Incidentally, when measuring the output and force characteristics, the double voltage should be gradually increased from zero voltage (when controlling the double gate voltage,
A large current will be applied to the lI'ET parallel circuit 3 from the beginning, and there is a strong possibility that a large rush current will flow in each FHTx+2, and in some cases, the 'M'l'x may be destroyed and the device may become unusable. occurs.

In the self-bias circuit 2 provided on the source S side of each FETI, a diode group 23 is provided in parallel with the bias resistor 21 so that the north current Is is in the forward direction. Since it is impossible to suppress this, it is necessary to make each FE 71 operate well even if a large source current Is flows.

As described above, according to the uninvented method, it is possible to reliably select the optimal measurement range for the solar cell to be tested for measurement pressure in a short time, and quickly perform measurements with small errors. The method of the present invention can be reliably achieved using the Zuromei apparatus.

[Brief explanation of drawings]

FIG. 1 is an explanatory block circuit diagram showing an example of the device of the present invention. l...Field effect transistor 2...Self bias circuit 3...FET parallel circuit 2
1... Bias resistance 22... Auxiliary bias resistance 23... Diode group 4... Gate voltage control mechanism 5... Constant current source 6.
...Auxiliary power supply for forced short circuit 7.9...External connection terminal 8...Current detector 10
... Voltage detector 11 ... Voltage/current measuring mechanism 12 ... Voltage polarity detector Agent Patent attorney Masahiko Oi

Claims (1)

[Claims] 1) A preliminary measurement is performed in which approximate values of the open circuit voltage and short circuit current of the solar cell to be measured are measured in advance, and the voltage range and current range of the measurement system are determined in accordance with the approximate values obtained by this preliminary measurement. is selected, and the output characteristics of the solar cell are measured under the selected voltage range and current range, and the preliminary measurement is performed by first setting the solar cell in an open state (= its output current and A small current for forced opening in the opposite direction is applied, the voltage across the solar cell is measured at that time to obtain an approximate value of the open voltage, and then a forced shorting current is applied to the solar cell in the same direction as its output current in a short circuit state. A method for measuring the output characteristics of a solar cell, characterized in that the measurement is performed to obtain an approximate value of short-circuit current by passing a current in addition to the output current and measuring the current flowing through the solar cell at that time. 2) A field effect transistor parallel circuit in which a large number of field effect transistors each having a self-bias circuit provided on the source side are connected in parallel, and a gate voltage that controls the voltage applied to the gate side C2 connected to the gate side of the field effect transistor parallel circuit. a control mechanism, a constant current source supplying a minute constant current connected to the drain side of the parallel field effect transistor circuit, an auxiliary power source for forced shorting connected to the source side of the parallel field effect transistor circuit, W1; A pair of external connection terminals connected to the drain side of the field-effect transistor parallel circuit and the source side via the forced shorting auxiliary power supply, and a voltage detector for detecting the voltage between the pair of external connection terminals. , a current detector that detects the current flowing between the pair of external connection terminals, and a voltage that has multiple measurement ranges and measures voltage and current values in response to detection signals from the voltage detector and current detector. - A solar cell output characteristic measuring device characterized by comprising a current measuring mechanism.