JP2014116451A - Solar cell and manufacturing method therefor - Google Patents

Abstract

A solar cell capable of improving conversion efficiency is provided.
SOLUTION: A solar cell 1, a strip-shaped collector electrode 5 for collecting a first conductivity type carrier generated in the solar cell 1 by light irradiation, and a place other than on a light receiving surface of the solar cell 1. A connection electrode (for example, a metal foil electrode 2B) provided, and a part or the whole other than the end of the collector electrode 5 is provided on the light receiving surface of the solar cell 1, and both ends of the collector electrode 5 are directly or indirectly. The connection electrode 2B has a structure in which the thickness of the connection electrode 2B is smaller than the thickness of the solar battery cell.
[Selection] Figure 1

Description

  The present invention relates to a solar cell and a manufacturing method thereof.

  An electrode for collecting the first conductivity type carrier generated by light irradiation is provided on the light receiving surface side, and an electrode for collecting the second conductivity type carrier generated by light irradiation is provided on the side opposite to the light receiving surface. The solar cell having a structure that needs to be provided on the light receiving surface includes a main grid electrode and a subgrid electrode that is narrower than the main grid electrode and extends in a branch shape from the main grid electrode. Therefore, a structure for collecting the first conductivity type carrier is generally used (see, for example, Patent Document 1).

  The number of main grid electrodes and sub-grid electrodes depends on the size of the solar cell, but in recent solar cells, in order to reduce the resistance loss of the main grid electrode and sub-grid electrode, the normal size (for example, the planar shape is Generally, a structure in which 2 to 4 main grid electrodes and several tens of sub grid electrodes are formed for a solar cell having a 125 mm square.

JP 2011-3721 A JP 2005-536894 A

  However, in the general structure as described above, the area loss (shadow loss) of the light receiving surface due to the main grid electrode and the subgrid electrode is about 6 to 7%, which is a main factor for reducing the conversion efficiency of the solar cell. It has become.

  Note that the photovoltaic module (solar cell) proposed in Patent Document 2 includes a photovoltaic semiconductor structure, an antireflection transparent conductive coating covering the upper surface of the photovoltaic semiconductor structure, and the photovoltaic semiconductor structure. It is necessary to align the thickness of the unit (solar cell) composed of the conductive coating covering the lower surface of the body and the thickness of the terminal bar or terminal frame, and the thickness of the terminal bar or terminal frame increases. Yes. And since the width | variety of a terminal bar or a terminal frame is also large corresponding to the thickness of a terminal bar or a terminal frame, the ratio of the unit (solar cell) area which occupies for the photovoltaic module (solar cell) area is small. Thus, the conversion efficiency of the photovoltaic module (solar cell) is low.

  An object of this invention is to provide the solar cell which can implement | achieve the improvement of conversion efficiency, and its manufacturing method in view of said situation.

  In order to achieve the above object, a solar battery according to the present invention includes a solar battery cell, a strip-shaped collector electrode that collects a first conductivity type carrier generated in the solar battery cell by light irradiation, and the solar battery. A connection electrode provided at a location other than on the light receiving surface of the cell, a part or all of the collector electrode other than the end portion is provided on the light receiving surface of the solar cell, and both ends of the collector electrode are directly or Indirectly connected to the connection electrode, the thickness of the connection electrode is smaller than the thickness of the solar battery cell (first configuration). The solar battery according to the present invention may have a structure in which the solar battery cell is not sealed, or may be a structure in which the solar battery cell is sealed and modularized, that is, a solar battery module. Good.

  In the solar cell having the first configuration, it is preferable that a plurality of collector electrodes are provided for one solar cell (second configuration).

  In the solar cell having the first or second configuration, the connection electrode is a metal foil electrode and is configured on the opposite side of the light receiving surface of the solar cell (third configuration). Is desirable.

  In the solar battery of the third configuration, the solar battery cell has a back electrode that collects the second conductivity type carrier generated by the solar battery cell by light irradiation, and is opposite to the light receiving surface of the solar battery cell. And having an insulating layer interposed between the metal foil electrode and the portion of the back electrode overlapping the metal foil electrode in a plan view as viewed from the light receiving surface side of the solar battery cell (first 4).

  The solar cell of the fourth configuration includes a metal foil electrode for a back electrode to which the back electrode is electrically connected, and a conductive layer interposed between the back electrode and the metal foil electrode for the back electrode. It is desirable that the metal foil electrode and the back electrode metal foil electrode be electrically separated and patterned with respect to the same solar battery cell (fifth configuration).

  In the solar cell having any one of the first to fifth configurations, the planar shape of the solar battery cell is substantially rectangular, and the collector electrode extends in a direction substantially parallel to a short side of the substantially rectangular shape. (Sixth configuration) is desirable.

  In the solar cell having any one of the first to sixth configurations, the collector electrode may be a metal wire (seventh configuration), and the collector electrode is a conductive resin electrode or a metal thin film electrode. (8th configuration).

  In the solar cell having the seventh configuration, it is desirable that the metal wire be covered with a conductive resin (9th configuration).

  In order to achieve the above object, a manufacturing method according to one aspect of the present invention is a method for manufacturing a solar cell having the seventh configuration, wherein a strip-shaped collector electrode that is a conductive resin electrode or a metal thin film electrode is used. A step of forming on the light receiving surface of the solar battery cell, a connection electrode provided at a place other than on the light receiving surface of the solar battery cell, and a thickness of the connection electrode smaller than the thickness of the solar battery cell, and both ends of the collector electrode And a step of indirectly connecting using a conductive member.

  In order to achieve the above object, a manufacturing method according to another aspect of the present invention is a method for manufacturing a solar cell having the above-described eighth configuration, and is a portion other than an end portion of a strip-shaped collector electrode that is a metal wire. Connecting to the light receiving surface of the solar cell, a connection electrode provided at a location other than on the light receiving surface of the solar cell, and having a thickness smaller than the thickness of the solar cell, and both ends of the collector electrode, Directly connecting the two.

  In the manufacturing method described above, it is desirable to include a step of dividing a cell having a substantially square planar shape into a plurality of the solar cells having a substantially rectangular planar shape.

  According to the present invention, instead of the main grid electrode, a connection electrode that is provided at a place other than the light receiving surface of the solar battery cell and has a thickness smaller than the thickness of the solar battery cell can be used. And the ratio of the photovoltaic cell area which occupies for a photovoltaic cell area can be enlarged, As a result, the improvement of conversion efficiency is realizable.

It is a fragmentary sectional view which shows the basic structure of the solar cell module which concerns on 1st Embodiment of this invention. It is a partial top view which shows the basic structure of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 1st process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 2nd process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 3rd process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is a top view for demonstrating the 3rd process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 4th process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 5th process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 6th process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the 7th process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is a top view which shows the pattern of the metal foil electrode currently formed in the wiring sheet. It is sectional drawing for demonstrating the 8th process of the manufacturing method of the solar cell module which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view which shows the basic structure of the solar cell module which concerns on 2nd Embodiment of this invention. It is a cross section of the metal wire which comprises a collector electrode. It is sectional drawing for demonstrating the 3rd process of the manufacturing method of the solar cell module which concerns on 2nd Embodiment of this invention. It is sectional drawing for demonstrating the 4th process of the manufacturing method of the solar cell module which concerns on 2nd Embodiment of this invention. It is sectional drawing for demonstrating the 5th process of the manufacturing method of the solar cell module which concerns on 2nd Embodiment of this invention. It is sectional drawing for demonstrating the 6th process of the manufacturing method of the solar cell module which concerns on 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
The basic structure of the solar cell module according to the first embodiment of the present invention is shown in FIGS. 1 is a cross-sectional view taken along line XX in FIG. In FIG. 2, the insulating base 2 </ b> A, the sealing material 7, and the transparent substrate 8 are not shown, and the outline of the metal foil electrode 2 </ b> B hidden by the solar battery cell 1 is illustrated by a dotted line. .

  The solar cell module according to this embodiment includes a solar cell 1, a wiring sheet 2, a conductive adhesive layer 3, an insulating adhesive layer 4, a collecting electrode 5, a metal wire 6, and a solar cell 1. A sealing material 7 to be sealed and a transparent substrate 8 provided on the surface of the sealing material 7 are provided.

  The solar battery cell 1 is provided with an electrode for collecting the first conductivity type carrier generated by light irradiation on the light receiving surface side, and an electrode for collecting the second conductivity type carrier generated by light irradiation. The solar cell has a structure that needs to be provided on the side opposite to the light receiving surface. As an example of such a structure, the back electrode 1A, the second conductivity type semiconductor layer 1B, and the first conductivity type semiconductor layer 1C shown in FIG. A structure in which the surface transparent electrode 1D is sequentially laminated on the entire surface can be given. The solar battery cell 1 is not limited to the pn type shown in FIG. 1 and may be a pin type. Further, it may be a homozygous type or a heterozygous type. One of the first conductivity type and the second conductivity type may be p-type and the other n-type.

  An example of the material of the back electrode 1A is copper. Examples of the material of the surface transparent electrode 1D include ITO (Indium Tin Oxide) and GZO (Gallium Zinc Oxide). Since GZO has a higher light transmittance than ITO, when GZO is used as the material of the surface transparent electrode 1D, the resistance loss of the surface transparent electrode 1D is larger than when ITO is used as the material of the surface transparent electrode 1D. In order to reduce the decrease in the amount of generated carriers, the thickness of the surface transparent electrode 1D is increased.

  The wiring sheet 2 includes an insulating substrate 2A and a metal foil electrode 2B formed on the surface of the insulating substrate 2A, and is disposed on the opposite side of the light receiving surface of the solar battery cell 1. The thickness of the metal foil electrode 2B may be smaller than the thickness of the solar battery cell 1, specifically, for example, about several tens of μm. In the metal foil electrode 2B, the first region R1 of the metal foil electrode 2B to which the collector electrode 5 is electrically connected and the second region R2 of the metal foil electrode 2B to which the back electrode 1A is electrically connected are the same. The battery cells 1 are electrically separated and further patterned so that a plurality of solar cells 1 can be electrically connected. As a material of the metal foil electrode 2B, for example, copper can be used as in the case of the back electrode 1A. However, the metal foil electrode 2B and the back electrode 1A may not be the same material.

  The conductive adhesive layer 3 is interposed between the back electrode 1A and the first region R1 of the metal foil electrode 2B facing the back electrode 1A, and bonds and electrically connects the two. As the conductive adhesive layer 3, for example, an Ag paste in which a large number of silver particles are contained in an epoxy resin can be used.

  The insulating adhesive layer 4 is a portion of the back electrode 1A that overlaps the second region R2 of the metal foil electrode 2B and the second region R2 of the metal foil electrode 2B in a plan view as viewed from the light receiving surface side of the solar battery cell 1. The two are bonded together and are electrically separated from each other. As the insulating adhesive layer 4, for example, an epoxy resin can be used.

  The collector electrode 5 is provided on the light receiving surface of the solar battery cell 1. In the present embodiment, a conductive resin electrode (for example, an electrode obtained by low-temperature baking Ag paste) or a metal thin film electrode (for example, plating electrode) is used as the collecting electrode 5.

  The strip-shaped collector electrode 5 extends in a direction substantially parallel to the short side of the solar battery cell 1 having a substantially rectangular planar shape, and both ends of the collector electrode 5 reach the long side of the solar battery cell 1. It is extended to. As shown in FIG. 2, it is desirable to provide a plurality of collector electrodes 5 for one solar battery cell 1. The intervals between the collector electrodes 5 may be equal intervals as shown in FIG. 2 or may be different intervals depending on the arrangement location. The width of the collector electrode 5 may be about 100 μm, for example.

  Both ends of the collector electrode 5 are indirectly connected to the second region R2 of the metal foil electrode 2B by the metal wire 6. The material of the metal wire 6 can be copper, for example, as in the case of the back electrode 1A and the metal foil electrode 2B, but the metal wire 6 and the back electrode 1A and the metal foil electrode 2B are not the same material. It doesn't matter.

  Examples of the material of the sealing material 7 include a cross-linked olefin copolymer and EVA (Ethylene-Vinyl Acetate). Examples of the material of the transparent substrate 8 include glass.

  Since the solar cell module according to the present embodiment has the above-described structure, the shadow loss can be reduced and the proportion of the solar cell area in the solar cell module area can be increased. As a result, the conversion efficiency can be improved by about 10% in comparison with a conventional solar cell module including a solar cell having a structure for collecting the first conductivity type carrier (see, for example, Patent Document 1).

  Here, an example of the manufacturing method of the solar cell module according to the present embodiment will be described with reference to FIGS.

  First, in the first step, the back electrode 1A, the second conductivity type semiconductor layer 1B, the first conductivity type semiconductor layer 1C, and the surface transparent electrode 1D are laminated in order on the entire surface, and the sun having a substantially square planar shape. The battery cell 10 is produced (see FIG. 3).

  In the next second step, the solar cell 10 is divided into two to obtain the solar cell 1 having a substantially rectangular planar shape (see FIG. 4). Unlike the example of the manufacturing method, the solar battery cell 10 may be divided into three or more. Further, unlike the present manufacturing method example, the solar cell may be used while the planar shape is substantially square, but in this case, the length of the collector electrode 5 is increased, and the resistance loss of the collector electrode 5 is increased. It is desirable that the solar battery cell is used with a substantially rectangular planar shape.

  In the next third step, the low-temperature fired Ag paste 9 is printed on the light receiving surface of the solar battery cell 1, that is, on the surface transparent electrode 1D (see FIG. 5). The printing pattern of the low-temperature fired Ag paste 9 is a pattern in which a plurality of strip shapes extending in a direction substantially parallel to the short side of the solar battery cell 1 are formed at equal intervals as shown in FIG.

  In the next fourth step, the low temperature fired Ag paste 9 is fired at a low temperature to obtain the collector electrode 5 (see FIG. 7).

  In the next fifth step, the insulating adhesive layer 4 is printed on the outer edge of the back electrode 1A (see FIG. 8). Thereby, the insulating adhesive layer 4 functions as a dam resin that prevents the conductive adhesive layer 3 from flowing out to the outer edge side of the back electrode 1A.

  In the next sixth step, the conductive adhesive layer 3 is printed on the central portion of the back electrode 1A (see FIG. 9).

  In the next seventh step, the solar cell 1 and the wiring sheet 2 are bonded together by the conductive adhesive layer 3 and the insulating adhesive layer 4 (see FIG. 10). The wiring sheet 2 is formed with a metal foil electrode 2B having a pattern as shown in FIG. With such a pattern of the metal foil electrode 2B, the solar battery cell 1 placed in the region R11 and the solar battery cell 1 placed in the region R12 can be connected in parallel and placed in the region R13. Solar cell 1 and solar cell 1 placed in region R14 can be connected in parallel, solar cell 1 placed in region R11 and solar cell 1 and region placed in region R12 The solar battery cell 1 placed on R13 and the solar battery cell 1 placed on the region R14 can be connected in series.

  In the next eighth step, both ends of the collector electrode 5 and the second region R2 of the metal foil electrode 2B are connected by the metal wire 6 (see FIG. 12).

  Finally, it is modularized by laminating with the sealing material 7 and the transparent substrate 8 to obtain a solar cell module having the structure shown in FIG.

Second Embodiment
The solar cell according to the second embodiment of the present invention is different from the solar cell according to the first embodiment of the present invention in that the collector electrode 5 is formed of a metal wire. Moreover, in this embodiment, as shown in FIG. 13, both ends of the collector electrode 5 are directly connected to the metal foil electrode 2B.

  The basic structure of the solar cell module according to this embodiment is shown in FIG. In the present embodiment, since the thickness of the collecting electrode 5 can be increased as compared with the first embodiment, the width of the collecting electrode 5 can be reduced. Therefore, the same effects as those of the first embodiment can be obtained, and the shadow loss can be further reduced.

  In addition, the diameter of the metal wire which comprises the collector electrode 5 is good to set it as about 50-150 micrometers, for example. Moreover, the metal wire which comprises the collector electrode 5 has a desirable structure where the metal wire 5A is coat | covered with the conductive resin 5B, for example, as shown in FIG. With such a structure, adhesion and electrical connection between the metal wire constituting the collector electrode 5 and the transparent electrode 1D can be easily performed by heating.

  As a material for the metal wire 5A, for example, copper can be used as in the case of the back electrode 1A and the metal foil electrode 2B, but the metal wire 5A and the back electrode 1A and the metal foil electrode 2B are not the same material. It doesn't matter. As the conductive resin 5B, for example, an Ag paste in which a large number of silver particles are contained in an epoxy resin can be used.

  Here, an example of the manufacturing method of the solar cell module according to the present embodiment will be described with reference to FIGS.

  The first step and the second step are the same as in the first embodiment.

  In the next third step, the insulating adhesive layer 4 is printed on the outer edge of the back electrode 1A (see FIG. 15). Thereby, the insulating adhesive layer 4 functions as a dam resin that prevents the conductive adhesive layer 3 from flowing out to the outer edge side of the back electrode 1A.

  In the next fourth step, the conductive adhesive layer 3 is printed on the central portion of the back electrode 1A (see FIG. 16).

  In the next fifth step, the solar battery cell 1 and the wiring sheet 2 are bonded by the conductive adhesive layer 3 and the insulating adhesive layer 4 (see FIG. 17). The pattern of the metal foil electrode 2B is the same as that in the first embodiment.

  In the next sixth step, the collecting electrode 5 is connected to the surface transparent electrode 1D and the second region R of the metal foil electrode 2B (see FIG. 18).

  Finally, it is modularized by laminating with the sealing material 7 and the transparent substrate 8 to obtain a solar cell module having the structure shown in FIG.

<Summary>
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention. For example, instead of the metal foil electrode 2B, a bar-shaped conductive member may be used as the connection electrode. Moreover, in embodiment mentioned above, although the wiring sheet 2 serves as the back sheet which protects the back surface of a solar cell module, you may comprise a wiring sheet and a back sheet by a separate member.

  The solar cell described above includes a solar cell (1), a strip-shaped collector electrode (5) that collects the first conductivity type carrier generated in the solar cell by light irradiation, and the solar cell. A connection electrode (R2) provided at a place other than on the light receiving surface, and a part or the whole other than the end of the collector electrode is provided on the light receiving surface of the solar cell, and both ends of the collector electrode are directly Alternatively, it is indirectly connected to the connection electrode, and the thickness of the connection electrode is smaller than the thickness of the solar battery cell (first configuration).

  According to such a configuration, since the shadow loss can be reduced and the ratio of the solar battery cell area to the solar battery module area can be increased, the conversion efficiency can be improved.

  In the solar cell having the first configuration, it is preferable that the solar cell has a configuration in which a plurality of the collecting electrodes are provided (second configuration).

  According to such a configuration, the current collection efficiency of the first conductivity type carrier is improved.

  In the solar cell having the first or second configuration, the connection electrode is a metal foil electrode and is configured on the opposite side of the light receiving surface of the solar cell (third configuration). Is desirable.

  According to such a configuration, it becomes easy to form the connection electrode on the sheet-like substrate.

  In the solar battery having the third configuration, the solar battery cell has a back electrode (1A) that collects a second conductivity type carrier generated by the solar battery cell by light irradiation, and the light receiving surface of the solar battery cell. And an insulating layer (4) interposed between the metal foil electrode and the portion of the back electrode overlapping the metal foil electrode in a plan view as viewed from the light receiving surface side of the solar battery cell. ) (A fourth configuration).

  According to such a structure, since a part of said connection electrode is a structure located directly under the said photovoltaic cell, the ratio of the photovoltaic cell area to a photovoltaic cell area can be made still larger.

  In the solar cell having the fourth configuration, the back-surface electrode metal foil electrode (R1) to which the back-surface electrode is electrically connected, and the conductive layer interposed between the back-surface electrode and the back-surface electrode metal foil electrode. (3), and the metal foil electrode and the back electrode metal foil electrode are preferably electrically separated and patterned with respect to the same solar cell (fifth configuration). .

  According to such a configuration, it becomes easy to form the connection electrode and the metal foil electrode for the back electrode on the same sheet-like substrate.

  In the solar cell having any one of the first to fifth configurations, the planar shape of the solar battery cell is substantially rectangular, and the collector electrode extends in a direction substantially parallel to a short side of the substantially rectangular shape. (Sixth configuration) is desirable.

  According to such a configuration, since the length of the collector electrode can be shortened, the resistance loss of the collector electrode can be reduced.

  In the solar cell having any one of the first to sixth configurations, the collector electrode may be a metal wire (seventh configuration), and the collector electrode is a conductive resin electrode or a metal thin film electrode. (8th configuration).

  When the collector electrode is a metal wire (5A), the collector electrode can be made smaller in width than the collector electrode is a conductive resin electrode or a metal thin film electrode. Can be reduced.

  In the solar cell having the seventh structure, it is preferable that the metal wire is covered with a conductive resin (5B) (a ninth structure).

  According to such a configuration, the collector electrode and the solar battery cell can be easily connected.

  The example of the solar cell manufacturing method described above is a method of manufacturing the solar cell having the above-described seventh configuration, in which a strip-shaped collector electrode that is a conductive resin electrode or a metal thin film electrode is provided on the light receiving surface of the solar cell. A step of forming, a connection electrode provided at a place other than on the light receiving surface of the solar battery cell, and having a thickness smaller than the thickness of the solar battery cell, and both ends of the collector electrode indirectly using a conductive member And a step of connecting to the device.

  Another example of the manufacturing method of the solar cell described above is a method of manufacturing the solar cell having the above-described eighth configuration, in which a portion other than the end portion of the strip-shaped collector electrode which is a metal wire is received by the solar cell. A step of connecting to a surface, and a connection electrode provided at a place other than on the light receiving surface of the solar cell, and having a thickness smaller than the thickness of the solar cell, and both ends of the collector electrode are directly connected Process.

  In the manufacturing method described above, it is desirable to include a step of dividing a cell having a substantially square planar shape into a plurality of the solar cells having a substantially rectangular planar shape.

DESCRIPTION OF SYMBOLS 1 Solar cell 1A Back surface electrode 1B 2nd conductivity type semiconductor layer 1C 1st conductivity type semiconductor layer 1D Surface transparent electrode 2 Wiring sheet 2A Insulating base material 2B Metal foil electrode (an example of a connection electrode)
3 Conductive adhesive layer (an example of a conductive layer)
4 Insulating adhesive layer (an example of an insulating layer)
5 collector electrode 5A metal wire 5B conductive resin 6 metal wire (an example of conductive member)
7 Sealing Material 8 Transparent Substrate 9 Low Temperature Firing Ag Paste 10 Solar Cell whose Planar Shape is Substantially Square

Claims (5)

Solar cells,
A strip-shaped collector electrode for collecting the first conductivity type carrier generated in the solar cell by light irradiation;
A connection electrode provided at a place other than the light receiving surface of the solar battery cell,
A part or all other than the end of the collector electrode is provided on the light receiving surface of the solar cell,
Both ends of the collector electrode are directly or indirectly connected to the connection electrode,
The solar battery, wherein the thickness of the connection electrode is smaller than the thickness of the solar battery cell.   The solar cell according to claim 1, wherein a plurality of the collecting electrodes are provided for one solar cell.   The solar cell according to claim 1, wherein the connection electrode is a metal foil electrode, and is disposed on a surface opposite to a light receiving surface of the solar battery cell. The solar battery cell has a back electrode for collecting the second conductivity type carrier generated in the solar battery cell by light irradiation, on the opposite surface of the light receiving surface of the solar battery cell,
4. The sun according to claim 3, further comprising an insulating layer interposed between the metal foil electrode and the portion of the back electrode overlapping the metal foil electrode in a plan view as viewed from the light receiving surface side of the solar battery cell. battery. A metal foil electrode for a back electrode to which the back electrode is electrically connected;
A conductive layer interposed between the back electrode and the metal foil electrode for the back electrode;
The solar cell according to claim 4, wherein the metal foil electrode and the metal foil electrode for back electrode are electrically separated and patterned with respect to the same solar cell.

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