JP2012134226A - Thin-film solar cell and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a thin-film solar cell, which can suppress occurrence of a hot spot due to a defect.SOLUTION: The manufacturing method of the thin film solar cell includes: a process (A) for forming a string where a plurality of thin film photoelectric conversion elements on which first electrode layers, photoelectric conversion layers and second electrode layers are sequentially laminated on surfaces of insulating substrates are electrically connected in series; and a process (B) for forming a plurality of division strings which are insulated, separated and arranged in a second direction orthogonal to a first direction by forming a division groove extending in the first direction being a direction of series connection by partially removing the string. The process (A) includes a defect inspection processing for measuring in-plane distribution of the defect of at least one layer among the first electrode layer, the photoelectric conversion layer and the second electrode layer. The process (B) includes a processing for deciding groove forming positions of the plurality of division grooves based on a measurement result of the in-plane distribution of the defect and a processing for forming the plurality of division grooves in the respective groove forming positions.

Description

  The present invention relates to a thin film solar cell having a plurality of thin film photoelectric conversion elements connected in series and a method for manufacturing the same.

In recent years, a thin film solar cell formed by a plasma CVD method using a gas as a raw material has attracted attention. Examples of the thin film solar cell include a silicon thin film solar cell made of a silicon thin film, a CIS or CIGS compound thin film solar cell, and the like, and development and production expansion are being promoted.
These thin-film solar cells are formed by laminating a transparent electrode, a photoelectric conversion layer, and a back electrode on a substrate by plasma CVD, sputtering, vacuum deposition, or the like (see, for example, Patent Document 1).

JP 2010-92893 A

In the method for manufacturing a thin-film solar cell described in Patent Document 1, after forming a laminated film by laminating a transparent electrode, a photoelectric conversion layer, and a back electrode on the first main surface of the insulating translucent substrate, the outer peripheral portion of the substrate Before removing the laminated film by the laser scribing process, the substrate with the laminated film is washed to remove foreign matters.
However, for example, the adhesive component contained in the paper sheet sandwiched between the substrates for protection when the substrate is carried in is adhered to the first main surface of the substrate, the electrode in the CVD film forming apparatus, the inner wall surface, or the like. In-film foreign matter that has fallen onto the first main surface of the substrate before or during film formation and is taken into the laminated film is difficult to remove by cleaning. There will still be foreign matter remaining on the substrate, which will cause defects in the laminated film.
And if the generated current flows through the defect during power generation of the thin film solar cell, the defect becomes an electric resistance and a hot spot that locally generates heat is generated, thereby degrading the power generation performance of the thin film solar cell and further failure There is also a case.

  This invention is made | formed in view of such a problem, and it aims at providing the manufacturing method of the thin film solar cell which can suppress generation | occurrence | production of the hot spot by a defect.

Thus, according to the present invention, a string formed by electrically connecting a plurality of thin film photoelectric conversion elements in which a first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially stacked on the surface of an insulating substrate. Forming step (A),
By partially removing the string to form a dividing groove extending in the first direction, which is the direction of the series connection, a plurality of lines that are insulated and separated from each other in a second direction orthogonal to the first direction Forming a split string (B),
The step (A) includes a defect inspection process for measuring a defect in-plane distribution of at least one of the first electrode layer, the photoelectric conversion layer, and the second electrode layer,
The step (B) includes a process of determining groove forming positions of the plurality of divided grooves based on the measurement result of the defect in-plane distribution, and a process of forming the plurality of divided grooves at each groove forming position. The manufacturing method of the thin film solar cell containing these is provided.
According to another aspect of the present invention, the thin film photoelectric conversion elements in which the first electrode layer, the photoelectric conversion layer, and the second electrode layer are sequentially laminated on the surface of the insulating substrate are electrically connected in series with each other. A plurality of divided strings are arranged in parallel in a direction perpendicular to the series connection direction through the division grooves, and a divided string having a small number of defects is formed with a narrow width in the direction orthogonal to the series connection direction of the divided strings having a large number of defects. A thin film solar cell having a wide width in a direction perpendicular to the series connection direction is provided.

  According to the present invention, the current flowing through the divided string with many defects is reduced, and the current flowing through the divided string with few defects is increased, thereby suppressing the generation of hot spots by suppressing the heat generation due to the defect resistance and the thin film solar cell. It is possible to improve the power generation efficiency.

It is a schematic perspective view which shows the thin film solar cell of Embodiment 1 of this invention. It is a process flow figure explaining the manufacturing method of the thin film solar cell of Embodiment 1 of this invention. It is a figure explaining the manufacturing method of the thin film solar cell of Embodiment 1 of this invention, Comprising: It is a schematic perspective view which shows the thin film solar cell before division | segmentation string formation. FIG. 4 is a schematic cross-sectional view of the thin film solar cell shown in FIG. 1 or 3 cut in the first direction. It is an example of the process of determining the groove formation position in S113 in the first embodiment. It is the schematic sectional drawing which cut | disconnected the thin film solar cell shown in FIG. 1 in the 2nd direction. It is the schematic explaining the reverse bias process process in Embodiment 1, and the reverse bias process means used at this process. It is another explanatory drawing which shows the process which determines the groove formation position in Embodiment 1 of this invention. It is a figure explaining the process which determines the groove formation position in the manufacturing method of the thin film solar cell of Embodiment 2 of this invention. It is a figure explaining the manufacturing method of the thin film solar cell of Embodiment 3 of this invention, Comprising: It is the schematic explaining the reverse bias process process and the reverse bias process means used at this process. It is a schematic perspective view which shows the reverse bias process means which can be used at the reverse bias process process in Embodiment 3. It is a conceptual diagram which shows the power supply of the reverse bias process means in Embodiment 3. 10 is a schematic configuration diagram illustrating an example of a moving mechanism of a reverse bias processing unit in Embodiment 3. FIG. It is a figure explaining formation of the division | segmentation string in Embodiment 3. FIG. It is a figure explaining formation of the division | segmentation string as a comparative example. It is a schematic perspective view which shows the reverse bias process means of Embodiment 4.

The method of manufacturing a thin film solar cell according to the present invention includes a structure in which a plurality of thin film photoelectric conversion elements in which a first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially stacked on an insulating substrate are integrated. It is a method of manufacturing.
Examples of the photoelectric conversion layer include a pn junction type, a pin junction type, a hetero junction type, and a tandem structure type in which a plurality of pn or pin junctions are stacked.
The present invention is applicable to both a super straight type thin film solar cell using a transparent substrate as an insulating substrate and a substrate type thin film solar cell using an opaque substrate.

In this method of manufacturing a thin film solar cell, a plurality of thin film photoelectric conversion elements in which a first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially laminated on the surface of an insulating substrate are electrically connected in series with each other. Forming a string (A);
By partially removing the string using a film removing means to form a dividing groove extending in the first direction which is the direction of the series connection, the strings are insulated from each other in the second direction orthogonal to the first direction. And (B) forming a plurality of divided strings arranged side by side.

The step (A) includes a defect inspection process for measuring a defect in-plane distribution of at least one of the first electrode layer, the photoelectric conversion layer, and the second electrode layer.
The step (B) includes a process of determining groove formation positions of the plurality of division grooves based on the measurement result of the defect in-plane distribution, and the plurality of divisions by the film removing unit at each groove formation position. Forming a groove.

  In the defect inspection process, a method for measuring the distribution of the defect in the plane of the string is not particularly limited. For example, an inspection using electroluminescence (EL) emission by applying a voltage, an inspection using a magnetic field generated by applying a voltage, a micro A defect inspection method corresponding to the type of film on the surface to be measured, such as a scope, SEM (scanning electron microscope), inspection using light reflection, transmission, or interference, can be appropriately employed.

Among these inspection methods, an EL emission inspection is employed in Embodiment 1 described later, and details are disclosed in JP 2009-105112 A, JP 2009-164165 A, and JP 2010-54365 A. Are listed.
In the EL emission inspection, the in-plane distribution of defects can be measured by causing EL emission by passing a forward current through each thin film photoelectric conversion element and observing the emission intensity distribution in the substrate plane. That is, a defect exists in a region where the light emission intensity is weak, and a region where the light emission intensity is particularly weak is identified as a region having a defect with a large electrical resistance value. Therefore, by using the EL emission inspection, not only the number of defects but also the resistance value of the defects can be identified.

In the step (B), when determining the groove forming position of the divided groove based on the result of the defect in-plane distribution measured by the defect inspection process, an area where a large number of defects exist among the plurality of divided strings. It is preferable that the groove forming position is determined so that the width of the split string including the second direction is narrow and the width of the split string including the region where a small number of defects exist is widened.
In this way, since the value of the current flowing through the narrow divided string is reduced, heat generation due to defects in the divided string can be reduced, and the generation of hot spots can be effectively suppressed. Reduction in the amount of power generated by the battery and occurrence of defects can be suppressed.

The step (B) can be specifically performed as in the following (I) or (II).
(I) In the process of determining the groove forming position in the step (B), the position can be adjusted in the second direction parallel to the fixed groove forming position and the fixed groove forming position where the groove forming position is fixed. An adjustment groove formation position is set, the position of the adjustment groove formation position is adjusted based on the distribution in the defect plane, and the divided grooves are formed at the adjusted adjustment groove formation position and the fixed groove formation position.
In this case, the position of the adjustment groove forming position is adjusted so that the width of the divided string including the region where a large number of defects are present is narrowed and the width of the divided string including the region where the small number of defects is present is widened.

(II) In the step of determining the groove forming position in the step (B), a plurality of groove forming scheduled positions arranged at equal intervals in the second direction are set, and the plurality of groove forming positions are set based on the defect in-plane distribution. A groove formation planned position is selected according to the number of divided grooves to be formed from among the groove formation planned positions, and the divided grooves are formed at the selected groove formation planned position.
In this case, the groove formation planned position is selected so that the width of the divided string including a region where a large number of defects are present is narrowed and the width of the divided string including a region where a small number of defects are present is widened.

  According to the above (I) or (II), the calculation of the defect distribution for each region, the determination process of the groove forming position according to the defect distribution, and the movement control of the film removing means for forming the divided groove at the groove forming position are simplified. Can be This point will be described in detail in Embodiments 1 and 2 described later.

As the film removing means, a laser scribing apparatus including a head unit (for example, a YAG laser and / or a YVO ₄ laser) that irradiates laser light, and a moving mechanism that moves the head unit in the first direction and the second direction. Can be used.
This laser scribing apparatus is suitable for performing the step (B) as in the above (I) or (II). Further, according to these lasers, only the thin film photoelectric conversion element can be easily and highly accurately divided without damaging the insulating substrate.
The laser scribing apparatus may include a metal mask. In other words, when a plurality of series-divided grooves are formed in each string by a laser, the masked portions are formed in the laser by masking part of the first and second electrode layers at both ends of the string with a metal mask. Thus, a plurality of divided strings electrically connected in parallel to each other can be formed at high speed.

This method of manufacturing a thin film solar cell may further include a step (C) of applying a reverse bias voltage to each thin film photoelectric conversion element in the divided string by using a reverse bias processing unit to perform a reverse bias process.
The reverse bias processing means has, for example, a plurality of voltage application units corresponding to a plurality of divided strings, and the voltage application units can contact the second electrode layers of two adjacent thin film photoelectric conversion elements in the divided strings. One having two pin-shaped electrodes can be used.
In this case, in the step (B), the plurality of groove forming positions are limited to positions where the pin-shaped electrodes of each voltage application unit of the reverse bias processing means can normally contact the plurality of divided strings formed by the divided grooves. It is preferred that

The reverse bias processing means includes a plurality of voltage application units corresponding to a plurality of divided strings, and a movement mechanism (first movement mechanism) that moves each voltage application unit in a first direction (series connection direction). The application unit includes a power source and two pin types that are simultaneously connected to the power source and contact the second electrode layers of two adjacent thin film photoelectric conversion elements in the same divided string to simultaneously apply different potentials. Use an electrode, an elevating drive unit that raises and lowers each pin-shaped electrode by connecting the two pin-shaped electrodes in an electrically insulated state, and a holding unit that holds the elevating drive unit Can do.
Further, the reverse bias unit may include a moving mechanism (second moving mechanism) that moves each voltage applying unit in a second direction orthogonal to the first direction.

By applying a reverse bias voltage to the thin-film photoelectric conversion element, a current flows through the short-circuit portion due to the defect, and the short-circuit portion is scattered and removed by Joule heat generated at that time, or the short-circuit portion is oxidized. Insulated.
As a result, it is possible to suppress a decrease in generated voltage due to a short circuit between adjacent photoelectric conversion elements and a hot spot due to a current concentration in the short circuit part.
According to the present invention, by changing the width of the divided string in accordance with the defect distribution of the thin film solar cell thin film, the occurrence of hot spots due to defects such as foreign matter in the unit cell is suppressed, and the reverse bias processing is performed between cells. Since the short circuit part which becomes a hot spot factor can be removed, generation | occurrence | production of a hot spot can be suppressed more compared with the conventional thin film solar cell, and the electric power generation fall can be suppressed.

  Hereinafter, embodiments of the method for manufacturing a thin-film solar cell of the present invention will be described in detail with reference to the drawings. The contents shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description. Hereinafter, the description will be made by taking a thin film solar cell having a superstrate type structure as an example, but the following description is basically applicable to a thin film solar cell having a substrate type structure. However, in the case of the substrate type structure, the order of forming the first electrode, the photoelectric conversion layer, and the second electrode is reversed, and the second electrode, the photoelectric conversion layer, and the first electrode are formed on the insulating substrate in this order. . In the case of the super straight type structure, the substrate side is the front side, and in the case of the substrate type structure, the substrate side is the back side.

(Embodiment 1)
FIG. 1 is a schematic perspective view showing a thin-film solar battery according to Embodiment 1 of the present invention.
This thin-film solar cell (thin-film solar cell after formation of a split string) 200 is provided on a transparent insulating substrate 101 with a first electrode layer 102 as a transparent electrode layer, a photoelectric conversion layer 103, and a second electrode layer as a back electrode layer. 104 includes a plurality of thin film photoelectric conversion elements Q2 and Q3 stacked in this order.
The plurality of thin film photoelectric conversion elements Q2 arranged in the first direction X are electrically connected in series, thereby forming a divided string.
The first embodiment exemplifies a case where four divided strings 106 a to 106 d are formed in parallel with each other with the divided groove 105 interposed therebetween.
Hereinafter, the thin film photoelectric conversion element is referred to as a cell.

As shown in FIG. 1, for example, in the divided string 106d, the transparent electrode layer 102 is separated by the first separation groove 107 filled with the photoelectric conversion layer 103, and the photoelectric conversion layer 103 and the back electrode layer 105 are the first. They are separated by two separation grooves 108. Then, the second electrode layer 104 of one cell Q2 passes through a contact line 109, which is a portion where the photoelectric conversion layer 103 is removed by patterning using laser light or the like. By being connected to the first electrode layer 102, the plurality of cells Q <b> 2 are electrically connected in series in the first direction X.
The same applies to the other divided strings 106a to 106c.

  As the transparent insulating substrate 101, a glass substrate having heat resistance and translucency in the subsequent film formation process, a resin substrate such as polyimide, and the like can be used. The first electrode layer 102 is made of a transparent conductive film, and for example, SnO2, ITO, ZnO or the like is used.

The p-type semiconductor layer is doped with p-type impurity atoms such as boron and aluminum, and the n-type semiconductor layer is doped with n-type impurity atoms such as phosphorus. The i-type semiconductor layer may be a completely non-doped semiconductor layer, or may be a weak p-type or weak n-type semiconductor layer that contains a small amount of impurities and has a sufficient photoelectric conversion function. Note that in this specification, “amorphous layer” and “microcrystalline layer” mean amorphous and microcrystalline semiconductor layers, respectively.
Materials of the semiconductor layers forming the photoelectric conversion layer is not particularly limited, for example, made of silicon-based semiconductor, CIS (CuInSe ₂₎ compound semiconductor, CIGS (Cu (In, Ga ) Se 2) compound semiconductor or the like. Hereinafter, the description will be given by taking as an example the case where each semiconductor layer is made of a silicon-based semiconductor. “Silicon-based semiconductor” means a semiconductor (silicon carbide, silicon germanium, etc.) containing amorphous or microcrystalline silicon, or silicon obtained by adding carbon, germanium, or other impurities to amorphous or microcrystalline silicon. To do. Further, “microcrystalline silicon” means silicon in a mixed phase state of crystalline silicon having a small crystal grain size (about several tens to thousands of thousands) and amorphous silicon. Microcrystalline silicon is formed, for example, when a crystalline silicon thin film is manufactured at a low temperature using a non-equilibrium process such as a plasma CVD method.

The configuration and material of the second electrode layer 104 are not particularly limited, but in one example, the second electrode 104 has a stacked structure in which a transparent conductive film and a metal film are stacked on a photoelectric conversion layer. The transparent conductive film is made of SnO ₂ , ITO, ZnO or the like. The metal film is made of a metal such as silver or aluminum.
The transparent conductive film and the metal film can be formed by a method such as CVD, sputtering, or vapor deposition.

Next, the manufacturing method of the thin film solar cell of this invention is demonstrated.
FIG. 2 is a process flow diagram illustrating a method for manufacturing a thin film solar cell according to Embodiment 1 of the present invention, and FIG. 3 is a diagram illustrating a method for manufacturing a thin film solar cell according to Embodiment 1 of the present invention. FIG. 4 is a schematic perspective view showing a thin-film solar cell before string formation, and FIG. 4 is a schematic cross-sectional view of the thin-film solar cell shown in FIG.
In the method for manufacturing a thin-film solar battery according to Embodiment 1, the strip cells Q1 in which the first electrode layer 102, the photoelectric conversion layer 103, and the second electrode layer 104 are sequentially stacked on the surface of the insulating substrate 101 are electrically connected in series. A step (A) for forming a connected string (a thin film solar cell before forming a divided string) 100 and a series connection for electrically insulating and separating the first electrode layer 102 and the second electrode layer 104 by using a film removing means. A step (B) of dividing the string 100 into a plurality of parts by forming a dividing groove 105 extending in the direction (first direction X) to form a plurality of divided strings 106a to 106d, and dividing using a reverse bias processing means A step (C) of applying a reverse bias voltage to each cell Q2 in the strings 106a to 106d and performing a reverse bias process.

In FIG. 2, S103 to S112 are included in the step (A), S113 is included in the step (B), and S115 is included in the step (C). Here, the symbol S means a step, and represents a unit of processing included in the thin film solar cell manufacturing process.
The step (A) includes a defect inspection process for measuring the defect in-plane distribution of the layer after forming at least one of the first electrode layer 102, the photoelectric conversion layer 103, and the second electrode layer 104. The defect inspection process is performed in S106, S108, and S112.
Further, in the step (B), the groove forming position of the division groove 105 is determined based on the result of the defect in-plane distribution measured in the defect inspection process, and the film removing means is driven along this groove forming position. The process of forming the dividing groove 105 is included.
As the film removing means, the laser scribing apparatus can be used.

In this method of manufacturing a thin-film solar cell, first, the thin-film solar cell 100 before forming the divided string shown in FIG. 3 is manufactured as follows.
First, in S101, the insulating substrate 101 in which a transparent conductive film (for example, a SnO ₂ film having a thickness of 500 to 1000 nm) is previously laminated on the main surface is carried into the production line using a substrate carry-in device.
In the case where an insulating substrate with a transparent conductive film is not used, a process of laminating the first electrode layer 102 with a thickness of about 500 to 1000 nm on the insulating substrate 101 by thermal CVD, sputtering, or the like after S101 or S102. To implement.

Next, in S102, the insulating substrate 101 is cleaned using the first substrate cleaning apparatus.
Next, in S103, a plurality of first electrode layers 102 are formed by removing a part of the transparent conductive film at a predetermined interval (about 7 to 18 mm) and forming a plurality of first separation grooves 107 by a laser scribing method. Form.

Subsequently, in S104, a part of the first electrode layer 102 located at the peripheral edge of the insulating substrate 101 is removed by a laser scribing method, whereby the management number in the production line of the thin film solar cell to be produced, QR Form markings such as codes.
Next, in S105, the insulating substrate 101 with the first electrode layer is cleaned using a second substrate cleaning apparatus.

Next, in S106, a first appearance inspection is performed to observe the position and shape of the first separation groove 107, the presence or absence of surface foreign matter or scratches on the first electrode layer 102, using an imaging device such as a CCD camera. .
Further, after or before the first appearance inspection, a first defect inspection process may be performed to measure the defect in-plane distribution of the first electrode layer 102. In the first defect inspection process, the inspection target film is a transparent conductive film, and can be performed by a microscope, SEM, defect inspection using light reflection, transmission, or interference. In addition, by using the same inspection means as the first appearance inspection in the first defect inspection processing, it is possible to perform appearance inspection and defect inspection with a common apparatus.

Subsequently, in S107, the photoelectric conversion layer 103 is stacked with a film thickness of about 300 to 3000 nm so as to cover the first electrode layer 102 separated by the first separation groove 107 by plasma CVD or the like. In the photoelectric conversion layer 103, a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer are sequentially stacked on the first electrode 102.
Next, in S108, the film thickness of the photoelectric conversion layer 103 is inspected using, for example, a semiconductor film thickness inspection apparatus.
Here, before and after the film thickness inspection, the second defect inspection process is performed by inspection using the EL emission or magnetic field, microscope or SEM, inspection using light reflection or interference, and the like. In-plane distribution can be measured.

Next, in S109, a plurality of contact lines 109 are formed by removing a part of the photoelectric conversion layer 103 at a predetermined interval (about 7 to 18 mm) by a laser scribing method.
Subsequently, in S110, the second electrode layer 104 is formed by laminating a transparent conductive layer and a metal layer in this order so as to cover the photoelectric conversion layer 103 by sputtering, vapor deposition, or the like. As a result, the contact line 109 is filled with the second electrode layer 104.
Next, in S111, a part of the photoelectric conversion layer 103 and the second electrode layer 104 is separated at a predetermined interval (about 7 to 18 mm) by a laser scribing method, and a plurality of second separation grooves 108 are formed. Form.
The laser scribing method for forming the first separation groove 107, the contact line 109, and the second separation groove 108 uses a YAG laser or YVO ₄ laser adjusted to a wavelength that is absorbed by a layer to be removed when each groove is formed. Can be used.
As described above, as shown in FIGS. 3 and 4, a thin film solar cell 100 in which a plurality of strip cells Q <b> 1 are connected in series to each other on the transparent insulating substrate 101 is formed.

Next, in S112, a third appearance inspection is performed to observe the position and shape of the second separation groove 108, the presence or absence of surface foreign matter or scratches on the second electrode layer 104, for example, using a CCD camera.
Furthermore, after or before or at the same time as the third appearance inspection, a third defect inspection process may be performed to measure the defect in-plane distribution of the second electrode layer 104 in the same manner as the second defect inspection process. By combining the data obtained by the first to third defect inspection processes, detailed defect in-plane distribution data can be obtained.
In the present embodiment, the first to third defect inspections are performed, but the present invention is not limited to this, and the defect inspection may be performed at least before the string division of S104. Moreover, this embodiment is an illustration about the step which implements each defect inspection, and can be implemented in the arbitrary positions between each process step.
In addition, in the present invention, the defect inspection of the photoelectric conversion layer is carried out because it is highly likely that many defects that become hot spots are generated because the deposits of the film forming apparatus are foreign matter in the film taken into the photoelectric conversion layer. It is preferable to do.

For example, in the EL emission inspection, the emission intensity distribution in the substrate surface is displayed as a defect map on the screen of the display unit, and is detected as the number of defects by analysis by the control unit.
The defect map and the defect count measurement data are communicated from the defect inspection apparatus via the server that controls the entire production line (not shown) or directly from the defect inspection apparatus to the string division processing apparatus in S113, which will be described later. The processing apparatus can set the formation position of the dividing groove based on the measurement data.
Up to here is the step (A) of forming the thin-film solar cell 100 before the divided string is formed, and then the step (B) of forming the divided string is performed.

In step (B), first, the string dividing process of S113 is performed.
In step (B) S113, first, processing for determining a groove forming position based on the defect inspection result is performed.
FIG. 5 shows an example of the process of determining the groove forming position in S113 in the first embodiment. At this time, as shown in the left diagram of FIG. 5, by dividing the in-plane defect distribution for each of the unit regions a to f in which the thin film solar cell 100 before the divided string is formed is equally divided in the second direction Y, The defect density per unit area can be calculated.
For example, regarding the number of defects included in each unit area, the area a is 10, the area b is 20, the area c is 40, the area d is 30, the area e is 999, and the area f is 10. Then, each number becomes the defect density in each region.
Then, by determining the groove formation position so that the number of unit regions included in the region with a high defect density is small and the number of unit regions included in the region with a low defect density is increased, a region including a large number of defects is included. The groove forming position is determined so that the width of the divided string is narrow and the width of the divided string including the region where a small number of defects are present is increased.
In the case of the left figure of FIG. 5, since the defect density of the area | region e is as high as 999 pieces / area | region, as shown to the right figure of FIG. By determining between d and e and between regions e and f as groove forming positions (thick line portions), region e is a divided string having the minimum width.

If the number of divided strings to be formed is three, the groove forming position may be two, but if the number of divided strings to be formed is four, the groove forming position is three. Determine another position. In the case of the right diagram in FIG. 5, the region between the regions b and c is also determined as the groove forming position (thick line portion).
Incidentally, the number of divided strings to be formed is determined by the specifications of the thin film solar cell to be manufactured, and information is transmitted to the string dividing processing device in advance as a processing condition.
Thus, by determining the three groove forming positions, the defect density of the region where the regions a and b are integrated is 15 / region [= (10 + 20) / 2], and the region where the regions c and d are integrated. Is determined to be 35 / area, area e is 999 / area, and area f is 10 / area.
5 illustrates the case where the thin film solar cell 100 is divided into unit regions a to f and the defect density in each region is detected, but the number of unit regions is further increased to increase the width of one region ( By further narrowing the second direction Y), it is possible to finely adjust the divided string width.

Next, by forming the dividing groove 105 in the thin film solar cell 100 along the determined groove forming position, as shown in the right view of FIG. 1 and FIG. 5 and FIG. Form. FIG. 6 is a schematic sectional view of the thin film solar cell shown in FIG. 1 cut in the second direction Y.
The thin-film solar cell 200 has divided strings 106a to 106d having different widths as shown in FIG. 6 by forming the divided grooves 105 at the groove forming positions determined in S112.

An example of the process of forming the dividing groove 105 will be described below.
First, one of the photoelectric conversion layer 103 and the second electrode layer 104 is formed by a laser scribing method of moving in the first direction X (direction orthogonal to the longitudinal direction of the strip cell Q1) while irradiating laser light from the transparent insulating substrate 101 side. The first dividing groove 105a is formed by removing the portions at a predetermined interval (about 75 to 250 mm). The YAG laser second harmonic (wavelength 532 nm) that is hardly absorbed by the first electrode layer (transparent electrode layer) 102 can be used as the laser light to be irradiated.
Next, the first electrode layer 102 is removed near the center of the first division groove 105a in the first direction X while irradiating laser light from the transparent insulating substrate 101 side, and the second division groove 105b is formed. Form. As a laser beam to be irradiated, a YAG laser fundamental wave (wavelength: 1.06 μm) absorbed by the first electrode layer 102 can be used.

In this way, by forming the dividing groove 105 composed of the first dividing groove 105a and the second dividing groove 105b, each band-like cell Q1 (see FIG. 3) is divided into a plurality of parts and electrically insulated. A thin film solar cell 200 having a plurality of divided strings 106a to 106d in which unit cells Q2 (see FIGS. 1 and 6) are electrically connected in series in the first direction X can be manufactured.
As shown in FIGS. 1 and 4, the cell Q3 on the end side in the X direction of each divided string is formed to have a shorter dimension in the first direction X than the other unit cells Q2. Q3 is not used as a photoelectric conversion element, but the second electrode 104 of each cell Q3 is used as an electrode in a reverse bias process described later.

1 shows a thin film solar cell 200 in which a plurality of divided strings 106a to 106d are electrically insulated by a divided groove 105 and are arranged in parallel. However, the plurality of divided strings 106a to 106d are electrically connected. You may produce the thin film solar cell connected in parallel (illustration omitted). In this case, before irradiating the laser beam from the transparent insulating substrate 1 side, the transparent insulation is performed so that the two strip cells Q1 on both ends in the first direction X of the thin film solar cell 100 shown in FIG. A metal mask is disposed on the outer surface of the substrate 101. Then, with the metal mask disposed, the laser beam is irradiated from the transparent insulating substrate 1 side as described above to form the first divided groove 105a and the second divided groove 105b, thereby forming the divided groove 105. Since the metal mask does not transmit laser light, the portion of the first electrode 102, the photoelectric conversion layer 103, and the second electrode 104 that are covered with the metal mask remain. As this metal mask, a metal sheet made of aluminum, stainless steel or the like having a thickness of about 1 to 3 mm can be used.
Accordingly, the first electrode 102 and the second electrode 104 of each unit cell Q2 on one end side in the first direction X of the plurality of divided strings 106a to 106d are connected in parallel by the common electrode, and the plurality of divided strings 106a. To 106d, the first electrode 102 and the second electrode 104 of each cell Q3 on the other end side in the first direction X are connected in parallel by a common electrode.

  Next, in S114, a portion located on the outer peripheral portion of the transparent insulating substrate 101 in the thin-film solar cell 200 is removed by irradiating with a laser beam, thereby forming a trimming region (not shown). This trimming region is an insulating region that imparts withstand voltage resistance necessary for the thin film solar cell.

Next, in S115, a reverse bias process is performed by applying a reverse bias voltage to each unit cell Q2 of the thin-film solar cell 200.
When there is a short-circuit portion in which the first electrode 102 and the second electrode 104 are in contact with each other through a pinhole formed in the photoelectric conversion layer 103 in the unit cell Q2, the reverse bias treatment removes the short-circuit portion, classifies the short-circuit portion, and The repair status can be determined.

FIG. 7 is a schematic diagram for explaining the reverse bias processing step and the reverse bias processing means used in this step in the first embodiment.
The reverse bias processing means 512 includes a power source 502 having an output terminal 501 that outputs a constant voltage, and a conductive member 505 that connects the output terminal 501 to each second electrode layer of the thin film solar cell 200.
The output terminal 501 includes a pair of output terminals 501a and 501b. In the first embodiment, a positive potential can be output to one output terminal 501a and a potential of 0 V can be output to the other output terminal 501b. The positive potential output to the output terminal 501a can be controlled to an arbitrary value. The conductive member 505 includes an electrode connection portion 505a and a wiring portion 505b.
A specific configuration of the reverse bias processing means that can be used in the reverse bias processing step in the first embodiment will be described later.

4 is a schematic cross-sectional view of the divided string 106d of the thin-film solar cell 200 according to Embodiment 1 cut in the first direction X, for example, and the first electrodes of the unit cells Q2 and the cells Q3 of the divided string 106d are 102f1˜ The reference numeral 102f5 is assigned, and the second electrodes are assigned reference numerals 104f1 to 104f6.
Hereinafter, the reverse bias processing step will be described with reference to FIGS.
In the reverse bias processing step, first, the pair of pin-shaped electrodes 505a1 and 505a2 of the reverse bias processing means is brought into contact with, for example, the adjacent second electrode layers 104f1 and 104f2 on the end side in the divided string 106f. The second electrode layer 104f1 of one unit cell Q2 is a back electrode on the n semiconductor layer side of the photoelectric conversion layer 103. The second electrode layer 104f2 of the other unit cell Q2 is connected to the first electrode layer 102f1 that is a transparent electrode layer on the p semiconductor layer side of the photoelectric conversion layer 103 in the one unit cell Q2. Therefore, if a positive potential is applied to one second electrode layer 104f1 and 0V is applied to the other second electrode layer 104f2, a reverse voltage is applied to the photoelectric conversion layer 103 of one unit cell Q2, and a reverse bias is applied. Processing is performed.

Specifically, for example, a potential of + 3V is output to the output terminal 501a and a potential of 0V is output to the output terminal 501b, and a voltage of 3V is applied between the second electrode layers 104f1 and 104f2 for 1 second. Thereby, a reverse voltage (reverse bias voltage) of 3 V is applied to the photoelectric conversion layer 103 for 1 second.
When almost no current flows due to this voltage application, it is determined that there is no short-circuit portion in the unit cell Q2, and the reverse bias processing is terminated, and the pair of pin-shaped electrodes 505a1 and 505a2 are shifted by one position. The reverse bias process of the next unit cell Q2 is performed in contact with the second electrode layers 104f2 and 104f3.
On the other hand, when a current of a predetermined value or more flows when a voltage is applied and the current does not decrease within 1 second of the voltage application period, the potential of the output terminal 101a is changed to 5 V, and a reverse bias voltage is applied for 1 second. If the current still does not decrease, it is determined that the reverse bias process cannot be performed, the process is terminated, and the next unit cell Q2 is subjected to the reverse bias process. Here, if the potential output to the output terminal 501a is too large, the pin junction of the unit cell Q2 is destroyed, so the voltage applied to the unit cell Q2 needs to be equal to or lower than the withstand voltage.

By the above procedure, all the unit cells Q2 of the divided string 106d in one column are sequentially subjected to reverse bias processing. Note that the cell Q3 in the portion of the second electrode 104f6 that is finally brought into contact with the output terminal 505a2 is not used as a photoelectric conversion element, and thus the reverse bias processing of the cell Q3 is omitted.
When the reverse bias processing for all the unit cells Q2 of the divided string 106d in one column is completed, all the unit cells Q2 of the next adjacent divided string 106c are sequentially reverse-biased in the same procedure, In addition, all the unit cells Q2 in the thin-film solar cell 200 are subjected to reverse bias processing.
The degree of short circuit can be classified as described above based on the data acquired during the reverse bias processing of each unit cell Q2. In addition, since the defect in-plane distribution is examined in the previous defect inspection process, in addition to being able to analyze which part of the thin-film solar cell is likely to have defects, the reverse bias process can be used to confirm the location of the short-circuit occurrence. it can. By feeding back these analysis results, it can be used for improving the film forming process of the first electrode layer, the photoelectric conversion layer, and the second electrode layer, and it becomes easy to grasp the problems on the film forming apparatus side, Correspondence becomes possible.

In addition, in a general thin film solar cell, when some unit cells of a divided string stop generating power by projection, a voltage generated in another unit cell is applied in the reverse direction to the pn junction of the unit cell that has stopped generating power. Is done. If there is a short circuit in the unit cell to which voltage is applied in the reverse direction, current concentrates and flows in the short circuit, heat is generated due to Joule heat, and the temperature rises locally between the electrode and the photoelectric conversion layer. There is a possibility that a so-called “hot spot phenomenon” occurs in which film peeling occurs or the substrate is cracked.
According to the first embodiment, the split grooves 105 are formed so that many short-circuited portions (defects) are accommodated in the narrow split strings 106a and 106f where it is difficult for a relatively large current to flow during power generation. Hot spots due to resistance are less likely to occur, and in addition to this, the short-circuited part is removed by reverse bias processing, which reduces the occurrence of hot spots during projection, thereby generating hot spots more than conventional thin-film solar cells. Can be further suppressed.

  Thereafter, as is normally done in the field, an insulation test is performed in S116, a characteristic test is performed in S117, and a substrate carry-out process is performed in S118, whereby a completed thin-film solar cell is obtained.

FIG. 8 is another explanatory view showing a process for determining a groove forming position in the method for manufacturing the thin-film solar battery of the first embodiment. In FIG. 8, the same elements as those in FIG. 1 are denoted by the same reference numerals.
Here, a specific and easy method for determining the groove forming position will be described.
The upper diagram of FIG. 8 shows the thin film solar cell 100 obtained after S112. The thin film solar cell 100 has regions R1 and R2 where a large number of defects are gathered.

  In this case, the method for determining the groove formation position is the method (II) described above. As shown in the upper diagram of FIG. 8, first, a plurality of predetermined groove formations indicated by dotted lines arranged at equal intervals in the second direction Y are formed. A position L3 is set in advance. In FIG. 8, 17 planned groove forming positions L3 that are equally divided in the second direction Y are set. In this case, three planned groove formation positions L3 pass through the vicinity of each of the regions R1 and R2.

Next, the width of the divided string having a large number of defects in the second direction Y is reduced, and the width of the divided string having a small number of defects in the second direction Y is increased. One or more (six in this case) planned groove forming positions L3 are selected from the above, and as a result, final six groove forming positions L indicated by solid lines are determined as shown in the lower diagram of FIG. .
By forming the dividing grooves at these groove forming positions L, narrow divided strings (four) in which a large number of defects are accommodated and wide divided strings (three) in which a small number of defects are accommodated. It is formed.
This case is also effective when using a laser scribing device in which the pitch width of movement of the head portion in the second direction Y is limited.

According to the present invention, in the step (A) of forming a string, after forming at least one film of the first electrode layer, the photoelectric conversion layer, and the second electrode layer, on the surface of the insulating substrate A defect inspection process is performed to measure the defect in-plane distribution of the films laminated on the substrate.
By this defect inspection process, it is possible to know how many defects having a large resistance value and defects having a small resistance value are present in the surface of the formed string.
Then, in the step (B) of forming a plurality of divided strings, a division groove having a large resistance value is formed by forming a dividing groove in the first direction in the vicinity of a region having a relatively large number of defects having a large resistance value. The string can be formed with a narrow width in the second direction. That is, it is possible to partition so that many defects having a large resistance value are contained in a specific divided string having a narrow width, and defects having a small resistance value are not included in the specific divided string as much as possible.
As a result, at the time of power generation of the obtained thin film solar cell, the voltage of each divided string is uniform regardless of the width, but the current value of the narrow divided string is larger than the current value of the narrow divided string. Therefore, it is possible to suppress a problem that a large current flows through a defect having a large resistance value of a narrow divided string and a hot spot is generated.

(Embodiment 2)
FIG. 9 is a diagram illustrating a step of determining a groove forming position in the method for manufacturing a thin-film solar cell according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected about the element which is common in Embodiment 1, and description may be abbreviate | omitted about a common matter.
In the second embodiment, a method for specifically and easily determining the groove forming position in the step (B) of forming the divided string will be described.
The upper diagram of FIG. 9 shows the thin film solar cell 100 obtained after S112. This thin-film solar cell 100 has, for example, regions R1 and R2 (a large number of dot portions) where a large number of defects are gathered. This is the measurement data of the defect in-plane distribution obtained by the previous defect inspection process. I know. It should be noted that a small number of defects are dispersed or no defects are found in other regions.

The method for determining the groove forming position in the second embodiment is the method (I) described above. As shown in the upper diagram of FIG. 9, first, the fixed groove forming position L1 indicated by a one-dot chain line with the fixed groove forming position is An adjustment groove formation position L2 indicated by a two-dot chain line whose position is adjusted in parallel to the second direction Y with respect to the fixed groove formation position L1 is set in advance.
In FIG. 9, when six divided strings are formed, five groove forming positions equally divided in the second direction Y are set as an initial state, and among them, the center and both sides are adjustment groove forming positions. The case where it is set to L2 and the remainder is set to the fixed groove forming position L1 is illustrated. In this case, one fixed groove forming position L1 passes through one region R1, and the other fixed groove forming position L1 passes near the other region R2.

Next, an adjustment groove is formed so that the width in the second direction Y of the divided string including the regions R1 and R2 where a large number of defects are gathered among a plurality of (in this case, six) divided strings to be formed is narrowed. The position of the position L2 is adjusted.
For example, as shown in the lower diagram of FIG. 9, the adjustment groove forming positions L2 on both sides close to one area R1 are positioned so as to approach one area R1 while maintaining parallel to one fixing groove forming position L1. While adjusting, the position of the adjustment groove forming position L2 close to the other region R2 is adjusted so as to approach the other region R2 while maintaining parallelism with the other fixed groove forming position L1.

In this way, by adjusting the position of each adjustment groove forming position L2, the final five groove forming positions L indicated by solid lines are determined as shown in the lower diagram of FIG.
By forming the dividing grooves at these groove forming positions L, narrow divided strings (three) in which a large number of defects are accommodated and wide divided strings (three) in which a small number of defects are accommodated. It is formed.
Here, in Embodiment 2, two fixed groove formation positions L1 and three adjustment groove formation positions L2 have been described. However, the present invention is not limited to this, and the number of L1 and L2 is a thin film solar cell to be manufactured. Each can be arbitrarily set within the range of the number of dividing grooves determined by the specifications.
Further, since all the positions are set to the adjustment groove forming position L2, a more optimal groove forming position can be determined.
In addition, in the manufacturing method of the thin film solar cell of Embodiment 2, since others are the same as that of Embodiment 1, description is abbreviate | omitted.

(Embodiment 3)
FIG. 10 is a diagram for explaining a method for manufacturing a thin-film solar cell according to Embodiment 3 of the present invention, and is a schematic diagram for explaining a reverse bias treatment step and reverse bias treatment means used in this step. FIG. FIG. 12 is a schematic perspective view showing a reverse bias processing means that can be used in the reverse bias processing step in the third embodiment, and FIG. 12 is a conceptual diagram showing a power source of the reverse bias processing means in the third embodiment. In addition, the same code | symbol is attached | subjected about the element common to Embodiment 1-3, and description may be abbreviate | omitted about a common matter.
The third embodiment is applied when the reverse bias processing step is different from that of the first embodiment and the groove forming position is more limited than in the first and second embodiments. Hereinafter, the reverse bias process in the third embodiment will be mainly described. In the third embodiment, the case where the thin-film solar cell 200 </ b> A having six divided strings 106 a to 106 f and having a divided string narrower toward the outside in the second direction Y is illustrated.

In the third embodiment, the unit cells Q2 in each divided string are sequentially reverse-biased using different power sources 502a to 502f for each divided string. That is, the reverse bias processing means of the third embodiment includes a plurality of reverse bias processing means of the first embodiment described with reference to FIG.
Therefore, in the reverse bias processing step of Embodiment 3, the unit cells Q2 of each divided string can be simultaneously reverse biased, and the reverse bias processing time of the thin film solar cell 200 can be further shortened. Note that the procedure for sequentially reverse-biasing each unit cell of the divided string is the same as in the first embodiment.

In this case, the divided strings are electrically separated by the divided grooves 105 (see FIG. 1), and the divided strings are individually separated without being affected by the potential applied to the second electrodes of the other divided strings. Can be reverse-biased. Further, even if the divided strings are electrically connected in parallel, they are not affected by the potential applied to the second electrodes of the other divided strings.
Moreover, even if one of the positive and negative terminals (for example, the negative terminal) of the plurality of power supplies is short-circuited (using a common wiring) and the same potential is used, the other terminal (for example, the positive-side terminal) is not short-circuited. Each divided string can be individually reverse-biased without being affected by the voltage applied to the other divided strings.

  In addition to the plurality of power sources 502 (502a to 502f) having the output terminals 501a and 501b described in FIG. 7, the reverse bias processing means includes two thin film photoelectric conversion elements (unit cells Q2) in each divided string 106a to 106f. Are further provided with a plurality of voltage application units U1 for applying a potential to each other, and a moving mechanism T for moving each voltage application unit U1 in the first direction X.

  The voltage application unit U1 is in a state where the two pin-shaped electrodes 505a1 and 505a2 that can contact the second electrode layers of the two thin film photoelectric conversion elements in the divided string and the two electrodes 505a1 and 505a2 are electrically insulated from each other. It has the raising / lowering drive part 601 which raises / lowers each electrode 505a1, 505a2, and the holding | maintenance part 602 which hold | maintains the raising / lowering drive part 601.

  Specifically, the holding portion 602 is formed of a box having a lower opening, for example. The elevating drive unit 601 is made of, for example, an expandable / contractible air cylinder, and the air cylinder body is fixed to the inner surface of the box so that the rod part of the air cylinder can move vertically to the lower opening side of the box. Has been. In this case, the moving mechanism T1 includes an air supply source (not shown), a flexible air tube that connects the air supply source and each air cylinder, and supplies compressed air to each air cylinder.

Further, for example, a flat plate 603 is horizontally attached to the lower end of the rod portion of the air cylinder, and two conductive plate members 604 are attached to the lower surface of the flat plate 603 with an interval therebetween, and the lower surface of each conductive plate member 604 is attached. The electrodes 505a1 and 505a2 are integrated. The two conductive plate members 604 are electrically connected to the output terminals 501a and 501b of the power source 502 via the wiring portions 505b and 505b.
Further, for example, the flat plate 603 is made of an insulating material so that the electrical insulation of the two conductive plates 604 and the electrical insulation of the two electrodes 505a1 and 505a2 are ensured, and each of the conductive plates 604 is formed. Are connected to the flat plate 603 by bolts and nuts.

  The wiring portions 505b and 505b and the above-described air tube are disposed on the lower surface side of the base 701 of the moving mechanism T1 so as not to prevent the movement of each voltage applying unit U1 in the X direction. Alternatively, slits extending in the first direction X are formed at a plurality of locations on the base 701, and the members of the moving mechanism T are placed in the space on the lower surface side of the base 701 by drawing the slits to the outside through the wiring portions 505b and 505b and the air tube. You may arrange only.

FIG. 13 shows a moving mechanism T1 that employs a ball screw mechanism to link a plurality of voltage application units U1.
The moving mechanism T1 is pivotally attached to the base 701 (see FIG. 11), a pair of parallel fixed pieces 702 fixed to both sides of the lower surface of the base 701 in the first direction X, and the pair of fixed pieces 702. The plurality of screw shafts 703, nut portions 704 screwed to the screw shafts 703, first bevel gears 705 attached to the rear ends of the screw shafts 703, and a pair of fixed pieces 702 A plurality of guide shafts 706, a main screw shaft 707 disposed on the rear end side of each screw shaft 703 and rotatably attached to the lower surface of the base 701, a motor M for rotating the main screw shaft 707, and a main screw shaft A plurality of second bevel gears 708 that are attached to 707 and mesh with the respective first bevel gears 705.

The plurality of screw shafts 703 and the plurality of guide shafts 706 are arranged alternately and in parallel, and one set of one screw shaft 703 and one guide shaft 706 corresponds to one voltage application unit U1. Yes.
The voltage application unit U1 has an upper wall of a box as a holding portion thereof fixed to a nut portion 704 of the moving mechanism T1 via an attachment member (not shown) and slidably attached to the guide shaft 706.

Since each voltage application unit U1 is attached to the moving mechanism T1 configured as described above, when each second bevel gear 708 is rotated together with the main screw shaft 707 by the motor M of the moving mechanism T1, The screw shafts 703 rotate together with the first bevel gear 705, whereby the voltage application units U1 move together with the nut portions in the first direction X at the same time.
According to the reverse bias processing means provided with the moving mechanism T1, when the electrode connection portion 501a1 of the voltage application unit U1 is moved onto the unit cell Q2 to be reverse biased of the divided string, 505a1 and 505a2 are lowered and brought into contact with the second electrode layers of the two unit cells Q2, and the reverse bias process described in the first embodiment is performed. After the processing, the electrodes 505a1 and 505a2 are raised, and similarly, the movement, the descent, the reverse bias process, and the rise are repeated to perform the reverse bias process for all the unit cells Q2.

  According to this reverse bias processing means, such reverse bias processing can be performed in parallel for a plurality of divided strings 106a to 106f. The plurality of power sources 502a to 502f corresponding to each voltage application unit U1 can be independently turned on / off, and each voltage application unit U1 can be moved up and down independently. When there is a difference in the reverse bias processing time depending on the unit cells Q2 to 106f, the power supply corresponding to the processed unit cell Q2 may be sequentially turned off and the voltage application unit U1 may be raised. In this way, it is possible to save power and to wait for the next unit cell Q2 to be reverse-biased.

  In addition, although the movement mechanism T in this embodiment illustrated the form which used the ball screw mechanism, it is connected with the holding | maintenance part 602 of several voltage application unit U1, and each holding | maintenance part 602 is interlock | cooperated or independently. In the present invention, the specific mechanism is not limited to the above as long as it is configured to be movable in one direction X. For example, a belt wheel mechanism (pulley mechanism), a chain / sprocket mechanism, or the like can be employed.

In the moving mechanism T of the various reverse bias processing means, each voltage applying unit U1 can move in the first direction X but cannot move in the second direction Y. In other words, the interval in the second direction Y between adjacent units having different electrodes 505a1 and 505a2 of each voltage application unit U1 is fixed.
Therefore, it is necessary to consider the following points in the process of forming the divided string before the reverse bias process.
FIG. 14 is a diagram for explaining the formation of divided strings in the third embodiment. More specifically, FIG. 14A shows the positional relationship between each divided string and the electrodes 505a1 and 505a2 of each voltage application unit U1 in the comparative example in which a plurality of divided strings are formed with the same width. ) Shows the positional relationship between each divided string and the electrodes 505a1 and 505a2 of each voltage application unit U1 in the case of Embodiment 3 of the present invention in which a plurality of divided strings are formed with different widths. 14A and 14B, a large number of dot regions indicate regions R1 and R2 where a large number of defects are gathered.

The left diagram in FIG. 14A and the left diagram in FIG. 14B show the string A before division.
In the case of the comparative example, as shown in the right diagram of FIG. 14A, since the string A is divided by the same width, the electrodes 505a1 and 505a2 of each voltage application unit U1 fixed at equal intervals are divided. It can contact the middle in the width direction of two adjacent cells QB1 of the string B1. At this time, since the divided string B1 is formed without considering the widths of the regions R1 and R2, hot spots are likely to occur.

Further, as shown in FIG. 15, when the split strings are formed so as to narrow the widths of the regions R1 and R2 without considering the reverse bias processing apparatus, all the voltage application units are collectively applied to all the split strings. The U1 electrodes 505a1 and 505a2 cannot be lowered. In this case, a part of the electrodes 505a1 and 505a2 is lowered to reversely bias only a part of the unit cells, and then the substrate or the entire moving mechanism T is shifted in the second direction Y so that the electrodes can be lowered to the untreated unit cells. In addition, it is necessary to carry out reverse bias processing by again lowering the electrodes 505a1 and 505a2 to an unprocessed unit cell. For this reason, the processing capability of the reverse bias processing device decreases as the number of movements increases.
In addition, when the position of the substrate or the moving mechanism T cannot be arbitrarily controlled and moved in the second direction Y, the reverse bias processing itself cannot be performed, and the reverse bias processing apparatus is temporarily stopped and the position of the electrode or the substrate is manually set. It is necessary to match them, and the operating rate of the apparatus decreases.
FIG. 15 is a diagram for explaining the formation of a divided string as a comparative example. In FIG. 15, reference numeral B3 indicates a divided string, QB3 indicates a cell, and elements similar to those in FIGS. Are given the same reference numerals.

  Therefore, in the third embodiment, as shown in the right diagram of FIG. 14B, the electrodes 505a1 and 505a2 of each voltage application unit U1 are adjacent to each divided string B2 in consideration of the widths of the regions R1 and R2. It is preferable to divide the string A so that it can come into contact with the two cells QB2. For this reason, the width of the divided string B1 having the regions R1 and R2 is as narrow as the widths of the regions R1 and R2, and as a result, the processing capability and operating rate of the reverse bias processing apparatus are not reduced. The thin film solar cell in which the hot spot is less likely to be generated can be manufactured as compared with the right figure of FIG. Note that the electrodes 505a1 and 505a2 of the voltage application unit U1 are in contact with two adjacent cells SB2 of the divided string B2 and are not in contact with the adjacent divided string B2, and the contact position is closer to the end than the middle in the width direction. But you can.

(Embodiment 4)
FIG. 16 is a schematic perspective view showing the reverse bias processing means of the fourth embodiment. In FIG. 16, the same components as those in FIG. 11 are denoted by the same reference numerals.
The reverse bias processing apparatus of the third embodiment shown in FIG. 11 includes a moving mechanism in which each voltage application unit U1 cannot move in the second direction Y (width direction of the divided string). However, the embodiment shown in FIG. 4 includes a moving mechanism that allows each voltage application unit U1 to move in the second direction Y.
Hereinafter, the points of the fourth embodiment different from the third embodiment will be mainly described.

  The bias processing means of the fourth embodiment includes a base 900 having four legs 901 and a top plate 902, and a plurality of first direction moving mechanisms that individually move a plurality of voltage application units U1 in the first direction X. XM and a plurality of second direction moving mechanisms YM that individually move each first direction moving mechanism XM in the second direction Y.

The first direction moving mechanism XM includes a ball screw mechanism or a belt wheel mechanism, and a downward opening rectangular parallelepiped case 920 that houses and holds the ball screw mechanism or the belt wheel mechanism.
The second direction moving mechanism YM is fixed to two places on the upper surface of the pair of guide shafts 911 that respectively connect the two pairs of legs 901 arranged in the second direction of the base 900 and the case 920 of each first direction moving mechanism XM. And a pair of cylinders 912 through which the pair of guide shafts 911 are inserted, a slit 913 formed in the second direction on the top plate 902 of the base 900, and a slit 913 fixed to one place on the upper surface of each case 920. A projecting piece 914 projecting upward through, a motor 915 capable of rotating forward and backward corresponding to each projecting piece 914 fixed in the vicinity of the slit 913 on the upper surface of the top plate 902 of the base 900, and each projecting piece 914 And a power transmission mechanism 916 provided between the motors 915.

The power transmission mechanism 916 includes, for example, a rack member 916a fixed to the upper surface of the protruding piece 914 and a pinion member 916b fixed to the tip of the drive shaft of the motor 915 and meshing with the rack member 916a.
According to the second-direction moving mechanism YM, the pinion member 916b rotates in the forward direction or the reverse direction together with the drive shaft of the motor 915, so that each cylindrical body 912 slides on each guide shaft 911, together with the rack member 916a. The case 920 moves in the second direction, and the voltage application unit U1 moves in the second direction. That is, the electrodes 505a1 and 505a2 of the voltage application unit U1 move in the second direction. At this time, the range in which the voltage application unit U1 can move in the second direction is a distance slightly shorter than the length of the rack member 916a in the second direction.

According to the fourth embodiment, since the electrodes 505a1 and 505a2 of each voltage application unit U1 can also move in the second direction, as in the third embodiment (FIG. 14B), the electrodes 505a1 and 505a1 of each voltage application unit U1. The adjustment range of the formation position of the dividing groove 105 is further expanded from the form in which the position in the second direction of 505a2 is fixed.
Therefore, compared with the third embodiment, the present embodiment can form the dividing groove 105 at a position more suitable for the defect distribution of the string formed on the substrate, and more effectively suppress hot spots. Is possible.

(Other embodiments)
1. In the present invention, one voltage application unit U2 may be configured to reverse-bias two divided strings, or one voltage application unit U2 may be configured to reverse-bias three to all divided strings. May be. That is, the voltage application unit can be extended in the first direction X to further increase the number of electrodes. In this way, the number of lifting operations during reverse bias application can be further reduced, and the process time for reverse bias processing can be further shortened. Moreover, the voltage application unit and the components of the moving mechanism can be further reduced, and the manufacturing cost can be further reduced. In this case, the number of lifting drive units, the number of power sources, the connection form between the power source and the voltage application unit, and the like can be selected as appropriate.
2. In the thin film solar cell, the number of divided strings and the number of unit cells in one divided string can be arbitrarily set according to the specifications of the solar cell to be manufactured. Correspondingly, it is preferable that the processing apparatuses including the laser scribing apparatus and the reverse bias processing apparatus are appropriately set and changed.

101 Insulating substrate (transparent insulating substrate)
102 1st electrode layer (transparent electrode layer)
103 Photoelectric conversion layer 104 Second electrode layer (back electrode layer)
100 Thin film solar cell (string)
105 Divided grooves 106a to 106f Divided strings 200 Thin film solar cells before formation of divided strings 512, 1512, 2512 Reverse bias processing means Q1 Band-shaped cell (thin film photoelectric conversion element)
Q2 unit cell Q3 cell T, T1 moving mechanism U1, U2 voltage application unit YM second direction moving mechanism XM first direction moving mechanism

Claims (7)

A step (A) of forming a string in which a plurality of thin film photoelectric conversion elements in which a first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially laminated on a surface of an insulating substrate are electrically connected in series; ,
By partially removing the string to form a dividing groove extending in the first direction, which is the direction of the series connection, a plurality of lines that are insulated and separated from each other in a second direction orthogonal to the first direction Forming a split string (B),
The step (A) includes a defect inspection process for measuring a defect in-plane distribution of at least one of the first electrode layer, the photoelectric conversion layer, and the second electrode layer,
The step (B) includes a process of determining groove forming positions of the plurality of divided grooves based on the measurement result of the defect in-plane distribution, and a process of forming the plurality of divided grooves at each groove forming position. The manufacturing method of the thin film solar cell characterized by including these.   In the step (B), based on the defect in-plane distribution, the second width of the divided string including a region where a small number of defects are present is reduced by narrowing the width in the second direction of the divided string including a region where a large number of defects are present. The method for manufacturing a thin-film solar cell according to claim 1, wherein the groove forming position is determined so as to widen the width in the direction.   In the step (B), a fixed groove forming position where the groove forming position is fixed and an adjustment groove forming position whose position can be adjusted in a second direction parallel to the fixed groove forming position are set, and the defect surface The manufacturing of the thin-film solar cell according to claim 2, further comprising: adjusting the position of the adjustment groove formation position based on an internal distribution and forming the divided grooves at the adjusted adjustment groove formation position and the fixed groove formation position. Method.   In the step (B), a plurality of groove formation scheduled positions arranged at equal intervals in the second direction are set, and divided grooves formed from the plurality of groove formation scheduled positions based on the defect in-plane distribution The manufacturing method of the thin film solar cell of Claim 2 including the process which selects a groove formation scheduled position according to number, and forms the said division | segmentation groove | channel in the selected groove formation scheduled position. Further comprising a step (C) of applying a reverse bias voltage to each thin film photoelectric conversion element in the divided string by using a reverse bias processing means to perform a reverse bias process,
The reverse bias processing means has a plurality of voltage application units corresponding to a plurality of divided strings,
The voltage application unit has two pin-shaped electrodes that can contact the second electrode layers of two adjacent thin film photoelectric conversion elements in the divided string,
5. The plurality of groove forming positions are determined at positions at which pin-shaped electrodes of each voltage applying unit can contact a plurality of divided strings formed thereafter. 6. Manufacturing method of thin film solar cell.   The step (A) includes a first defect inspection process for measuring a defect in-plane distribution of the first electrode layer, a second defect inspection process for measuring a defect in-plane distribution of the photoelectric conversion layer, and the second electrode. The manufacturing method of the thin film solar cell as described in any one of Claims 1-5 including the 3rd defect inspection process which measures the defect in-plane distribution of a layer.   A divided string in which thin-film photoelectric conversion elements in which a first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially stacked on the surface of an insulating substrate are electrically connected in series to each other is connected in a series connection direction via a division groove. The width of the divided string with a large number of defects is narrow in the direction perpendicular to the series connection direction, and the width of the divided string with a small number of defects is wide in the direction perpendicular to the series connection direction. A thin film solar cell formed.

Images