JP3049241B1 - How to remove short circuit part of solar cell - Google Patents

Abstract

An object of the present invention is to provide a method for reliably removing a short-circuited portion without destroying a portion other than a short-circuited portion generated in a thin-film solar cell by a reverse voltage applied between electrodes. A first electrode layer, a semiconductor layer, and a second electrode layer are formed on a substrate.
In a solar cell including one or a plurality of solar cells in which the electrode layers are sequentially formed, a reverse voltage less than a withstand voltage is applied in a reverse direction to both positive and negative electrodes of the solar cell to remove a short circuit portion. In the method of removing a short-circuited portion of a solar cell, the reverse applied voltage is substantially alternating current whose value mainly includes the reverse direction shown in FIGS. 1A to 1D and partially includes a forward component changes periodically with time. (Sine wave, half sine wave, sawtooth wave).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a short-circuit portion generated in a thin-film solar cell using an amorphous semiconductor or the like. More specifically, the present invention relates to the above-described thin-film solar cell, wherein a short-circuit portion occurs between the substrate-side electrode and the back-side electrode sandwiching the photoelectric conversion semiconductor layer contributing to power generation, and the reverse direction below the withstand voltage. The present invention relates to a method of applying a voltage and removing or oxidizing a short-circuited portion by Joule heat generated at that time to perform insulation.

[0002]

2. Description of the Related Art As shown in FIG.
A first electrode 2 formed on one surface of an insulating substrate 1 in a predetermined pattern, a photoelectric conversion semiconductor layer 3 made of an amorphous semiconductor provided on a surface of the first electrode 2, A plurality of solar cells 5a, 5b, and 5c each including a second electrode 4 provided on the surface of the photoelectric conversion semiconductor layer 3 are provided on one substrate 1, and the first electrode 2a of the solar cell 5a is provided. And the second electrode 4b of the adjacent solar cell 5b is connected in series.

When a glass substrate or a transparent resin substrate is used as the insulating substrate 1 of such a solar cell, the first
A transparent electrode material such as ITO (Indium Tin Oxide: indium oxide mixed with tin oxide) is used as the electrode 2, and a metal electrode material is used as the second electrode 4. When a non-translucent substrate material is used as the insulating substrate 1, a metal electrode material is used as the first electrode 2 and the second electrode 4 is used.
Is used as a transparent electrode material.

When the semiconductor layer 3 is made of an amorphous silicon-based semiconductor, amorphous silicon, hydrogenated amorphous silicon, hydrogenated amorphous silicon carbide, amorphous silicon nitride, etc., as well as silicon and carbon , Germanium, tin, etc., and amorphous silicon made of an alloy with another metal are used.
Semiconductor materials configured in a type, nip type, ni type, pn type, MIS type, heterojunction type, homojunction type, Schottky barrier type or a combination thereof are used. Further, the semiconductor layer is not limited to the silicon type,
It may be composed of an S type, a GaAs type, an InP type, or the like.

In such a solar cell, for example, a short circuit occurs between the first electrode 2b and the second electrode 4b of the solar cell 5b due to a pinhole generated in the photoelectric conversion semiconductor layer 3b at the time of manufacturing. When this occurs, the short circuit is removed or the short circuit is oxidized for insulation.

In order to remove a short-circuit portion generated between the first electrode 2b provided on the substrate side of the solar cell 5b and the second electrode 4b provided on the back side of the photoelectric conversion semiconductor layer 3b, , Electrodes 4b and 4c are brought into contact with the probe electrodes 6a and 6b to sandwich the photoelectric conversion semiconductor layer 3b contributing to power generation.
Between the second electrode 4b and the second electrode 4b, a DC reverse voltage of a reverse breakdown voltage (reverse bias voltage) or less (0 V side) or a reverse voltage of a pulse-like rectangular wave as shown in FIG. Then, the current is concentrated on the short-circuited portion, and the metal of the short-circuited portion is oxidized by the generated Joule heat to form an insulator, or the metal is scattered to remove the short-circuited portion.

However, a solar cell is equivalent to a diode. When a reverse voltage is applied between the electrode 2 and the electrode 4, the first electrode 2, the photoelectric conversion semiconductor layer 3, and the second electrode 4 The solar cell 5 functions as a capacitor and accumulates electric charges between the two electrodes 2 and 4.

As described above, when a DC voltage is applied between the electrodes 2 and 4, even after the applied voltage is suddenly removed,
Electric charges remain between the electrodes 2 and 4, and there is a problem that the voltage caused by the electric charges causes destruction to occur in a weak portion other than the short-circuit portion of the photoelectric conversion semiconductor layer 3.

In order to avoid such a problem due to the accumulated charge, a method of applying a pulse-like rectangular wave voltage between the electrodes 2 and 4 is to reduce the withstand voltage in order to prevent a high voltage from being accumulated in the solar cell. A near enough voltage cannot be applied, and a reverse voltage pulse of about 4 V is applied. However, at such a low voltage, sufficient energy cannot be applied to the short-circuited portion, and there is a problem that the generated short-circuited portion cannot be removed or oxidized due to the generated Joule heat, and the short-circuited portion is accumulated. A phenomenon has occurred in which a normal portion other than a short-circuit portion is destroyed by discharging electric charges through a portion of the semiconductor having a low withstand voltage.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended to eliminate a short-circuit portion generated in a thin-film solar cell.
It is an object of the present invention to provide a method capable of reliably removing a short-circuited portion without breaking portions other than the short-circuited portion by a reverse voltage applied between electrodes.

[0011]

According to the present invention, a substantially alternating voltage whose value periodically changes with time is applied between the electrodes 2 and 4, and the applied voltage waveform mainly includes a reverse voltage component. By making the voltage waveform partially include a forward component, the electric charge accumulated in the solar cell is discharged to protect the solar cell.

According to the first aspect of the present invention, there is provided a solar cell including one or a plurality of solar cells in which a first electrode layer, a semiconductor layer, and a second electrode layer are sequentially formed on a substrate. A method for removing a short-circuit portion of a solar cell, in which a reverse voltage less than the withstand voltage is applied in the opposite direction to the two poles, and the short-circuit portion is removed. A voltage that includes a forward component and whose value changes periodically with time, and is a forward voltage of 0.5 V or less.
And a sine wave that alternates between a reverse voltage of 1 V or more .

According to a second aspect of the present invention, a first electrode is provided on a substrate.
One or more layers in which a layer, a semiconductor layer, and a second electrode layer are sequentially formed.
Solar cell in a solar cell including a number of solar cells.
Reverse voltage below the withstand voltage in the opposite direction to both the positive and negative
How to remove short-circuit part of solar cell by applying pressure to remove short-circuit part
The reverse applied voltage mainly includes a reverse component.
And the value that partially includes the forward component
The forward voltage of 0.2 V or less
A half-wave of a sine wave that alternates between reverse voltages of 1 V or more was used.

According to a third aspect of the present invention, a first electrode is provided on a substrate.
One or more layers in which a layer, a semiconductor layer, and a second electrode layer are sequentially formed.
Solar cell in a solar cell including a number of solar cells.
Reverse voltage below the withstand voltage in the opposite direction to both the positive and negative
How to remove short-circuit part of solar cell by applying pressure to remove short-circuit part
The reverse applied voltage mainly includes a reverse component.
And the value that partially includes the forward component
And a forward voltage of 0.5 V or less.
A reverse voltage of 1 V or more was set as a back and forth sawtooth wave .

The invention according to claim 4 is the invention according to claims 1 to
In the method for removing a short-circuited portion of a solar cell according to any one of the above items 3, the capacity and resistance of the solar cell element when a reverse voltage is applied are defined.
Apply a voltage with a frequency of a fixed time constant in the opposite direction.
I made it.

According to a fifth aspect of the present invention, in the method for removing a short-circuit portion of a solar cell according to the fourth aspect, the periodic change with time is provided.
The repetition frequency of the reverse applied voltage is
It was set to 0 Hz .

According to a sixth aspect of the present invention, in the method for removing a short-circuit portion of a solar cell according to the fourth aspect, the periodic change with time is provided.
The repetition frequency of the reverse applied voltage is 50 to 120
Hz .

According to the method of the present invention, the voltage is applied between the electrodes.
Reverse voltage can be instantaneously increased to about 10V
And generate heat only in the short-circuited part to remove it reliably.
Can be

Further, according to the present invention, between the electrodes 2 and 4
The accumulated charge is released during the period when the forward voltage is applied.
Is charged and accumulated by the accumulated charge,
There is no risk of destruction.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Short-circuit part of solar cell according to the present invention
The removal method will be described. For solar cells with short circuits
The method of flowing a current is the same as the method shown in FIG. Book
In the present invention, the probe electrode 6a and the probe electrode 6b
The voltage to be applied is mainly for the reverse component, not DC.
Values including some forward components change periodically with time
It is characterized in that it is substantially an AC voltage. That is,
Voltage applied to probe electrode 6a and probe electrode 6b
, As shown in FIG.
Both have a sinusoidal waveform voltage that partially includes the forward component.
The peak value of the directional component is set to 0.5 V, and the peak value in the reverse direction is set to 1.
V or more.

Applying a reverse voltage having such a waveform
Thus, when the forward component is applied, the voltage is stored between the electrodes 2 and 4.
The accumulated charge is discharged and can damage normal parts.
Disappears. Furthermore, consider the effects of charge accumulation.
The reverse applied voltage can be instantaneously marked up to 10V.
Can be added, and the short-circuit part is reliably removed.
can do.

FIG . 1B shows another form of the reverse applied voltage.
In the diagram shown, a backward sign whose value changes periodically with time
Make the reverse component of the applied voltage a half sine wave and
The direction component was a rectangular wave of 0.2 V or less. Again, the sine
The peak value of the wave is almost the same as the reverse bias voltage of the solar cell.
Reverse voltage was used. Apply a reverse voltage with such a waveform
As a result, the charge accumulated between the electrodes 2 and 4 is
Discharge occurs during the directional component application period, causing damage to normal parts.
No more. In addition, consider the effects of charge accumulation.
The reverse applied voltage can be increased to 10 V instantaneously.
Can be applied in the
Can be removed.

FIG . 1C shows another form of the reverse applied voltage.
In the diagram shown, a backward sign whose value changes periodically with time
The applied voltage was a rectangular wave. In this case, too,
The forward component was set to 0.2 V or less. Such a waveform
Is applied between the electrodes 2 and 4 by applying the reverse voltage of
The accumulated charge is discharged during the forward component application period,
No destruction of parts. In addition, charge storage
Since the influence of the product does not need to be considered,
It is possible to apply up to 10V instantaneously,
The short-circuit portion can be reliably removed.

FIG . 1D shows another form of the reverse applied voltage.
In the diagram, the saw mainly includes the reverse component of the reverse applied voltage.
A Gili wave and a forward component of 0.2 V or less
Was. Also in this case, the electric charge accumulated between the electrodes 2 and 4 is normal.
Discharged during the application of the directional component, causing destruction in normal parts
Disappears. In addition, the reverse applied voltage also accumulates charge
Instantaneously up to 10V
Voltage can be applied, and
You can leave.

Sixty short-circuited cells integrated in series
Then, the reverse voltage shown in FIG.
Added, the short circuit in 58 cells was removed and recovered.
However, in the conventional method of applying a rectangular wave pulse of 4 V, 50
Only the individual recovery has been recovered, and the method of removing the short-circuit portion according to the present invention
It turns out that the method is extremely effective.

In the present invention, the reverse direction of the substantially alternating current is used.
As an applied voltage power supply, use an alternating power supply of about 60hz
But the value changes periodically over time
The repetition frequency of the substantially alternating current is changed in the opposite direction to the capacity C of the solar cell.
Let the frequency match the time constant defined by the resistor R.
In this way, the accumulated charge is sufficiently discharged to achieve the purpose
be able to. Furthermore, in the present invention, the value is time and
The repetition frequency of the substantially alternating current, which changes periodically, is set to 20
To 1000 Hz, preferably 50 to 120 Hz
Thus, the accumulated charges can be reliably discharged.

[0027]

【The invention's effect】 According to the present invention, a high reverse voltage is applied
Can be removed by applying a reverse voltage.
In short-circuited areas where the voltage
Can only be removed with a high reverse voltage that could not be removed
The short circuit part can be removed.

Further, according to the present invention, the reverse applied voltage
Is defined as AC, defined by the capacity C of the solar cell and the resistance R in the opposite direction.
By setting the frequency to match the time constant
Applied voltage waveform can follow power supply voltage waveform
It became.

[Brief description of the drawings]

FIG. 1 is a diagram showing a reverse applied voltage waveform according to the present invention and a conventional technique.

FIG. 2 is a diagram illustrating a configuration of a solar cell and a method for removing a short-circuit portion.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 first electrode 3 photoelectric conversion semiconductor layer 4 second electrode 5 solar cell 6 probe electrode 10 solar cell

Claims (6)

(57) [Claims] A first electrode layer, a semiconductor layer, and a second electrode layer on a substrate;
In a solar cell including one or a plurality of solar cells in which an electrode layer is sequentially formed, a short-circuit portion is removed by applying a reverse voltage of a withstand voltage or less in a reverse direction to both positive and negative electrodes of the solar cell. a short-circuit portion removing method of the solar cell, the reverse applied voltage is a voltage value that contains the part forward component as the main reverse direction component is changed periodically with time, 0.5V The following forward voltage and reverse more than 1V
A method of removing a short-circuited portion of a solar cell, wherein the method is a sine wave that moves between direction voltages . A first electrode layer, a semiconductor layer, and a second electrode layer on the substrate;
One or more solar cells in which the electrode layers of
The positive and negative poles of the solar cell
And apply a reverse voltage less than the withstand voltage in the reverse direction to
A method for removing a short-circuited portion of a solar cell, comprising:
That the value containing the component changes periodically with time.
Forward voltage of 0.2 V or less and reverse voltage of 1 V or more
It is a half wave of a sine wave that moves between the counter voltages.
Short circuit portion removing method of the solar cell to be. A first electrode layer, a semiconductor layer, and a second electrode layer on the substrate;
One or more solar cells in which the electrode layers of
The positive and negative poles of the solar cell
And apply a reverse voltage less than the withstand voltage in the reverse direction to
A method for removing a short-circuit portion of a solar cell, wherein the reverse applied voltage is mainly a backward component and partially forward.
That the value containing the component changes periodically with time.
Forward voltage of 0.5 V or less and reverse voltage of 1 V or more
A method for removing a short-circuited portion of a solar cell, comprising a sawtooth wave that moves back and forth in a counter voltage . 4. The capacity of a solar cell element when a reverse voltage is applied.
And a voltage at the frequency of the time constant specified by the resistor in the opposite direction.
The method according to any one of claims 1 to 3, wherein
2. The method for removing a short-circuited portion of a solar cell according to claim 1 . 5. An inverse direction which changes periodically with time.
The repetition frequency of the applied voltage is 20 to 1000 Hz.
The method for removing a short circuit portion of a solar cell according to claim 4 . 6. An inverse direction which changes periodically with time.
The repetition frequency of the applied voltage is 50 to 120 Hz
The method for removing a short circuit portion of a solar cell according to claim 4 .