JP4585652B2 - Photovoltaic element and method for producing photovoltaic element - Google Patents

Description

【０１３１】
高温高湿試験に関しては、何れのモジュールにおいてもほとんど変化はなかったが、太陽電池モジュールＡだけが若干の低下を示しており、導電性接着剤の樹脂種の影響であると考えられる。
【０１３２】
また、動荷重試験に関しては、何れのモジュールにおいても変換効率の低下が全く無く良好であったが、その後、太陽電池モジュールＡ〜Ｄに対して導電性接着剤を顕微鏡で観察したところ、太陽電池モジュールＡ、Ｂ、Ｃにおいては導電性接着剤にひび割れが見られた。この結果は、使用している導電性接着剤の柔軟性に起因している現象と考えられる。
【０１３３】
以上の結果より、本発明の構成については、充分信頼性を有することが分かった。また、中でも、エポキシ樹脂やアクリル樹脂を使用した系については、とりわけ信頼性が良好であることが分かった。
【０１３４】
【発明の効果】
以上説明したように、本発明によって集電形態が改善され、従来課題であったバスバーとワイヤー部の抵抗ロスを非常に低減することが可能となった。また、それによって初期変換効率の非常に高い光起電力素子を得ることができた。さらには、これらの光起電力素子の製造方法において、生産性、コスト、容易性に優れた製造方法を提供できた。
【図面の簡単な説明】
【図１】本発明の実施態様例の光起電力素子の概略図である。
【図２】本発明の集電電極の模式的概略図である。
【図３】本発明の集電電極の模式的概略図である。
【図４】本発明に係るアモルファスシリコン系太陽電池の構成を模式的に示す断面図である。
【図５】本発明の光起電力素子の製造方法を説明する概略図である。
【図６】従来の光起電力素子の概略図である。
【符号の説明】
１０１、５０１、６０１ 光起電力素子
１０２、５０２、６０２ エッチングライン
１０３、４０７、５０４、６０３ 集電電極
１０４、２０１、３０１、６０４ 金属ワイヤー
１０５、２０２、６０５ 導電性被覆層
１０６、５０７、６０６ 金属バスバー
１０７、５０６ 導電材
１０８、５０３、６０７ 絶縁部材
３０２ 第１被覆層
３０３ 第２被覆層
４０１ 基板
４０２ 下部電極
４０３、４１３、４２３ ｎ型半導体層
４０４、４１４、４２４ ｉ型半導体層
４０５、４１５、４２５ ｐ型半導体層
４０６ 上部電極
５０５ 被覆層除去部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photovoltaic device. More specifically, the present invention relates to a photovoltaic element having a collecting electrode structure for obtaining higher efficiency than conventional ones.
[0002]
[Prior art]
Solar cells using photovoltaic elements are attracting attention as an alternative energy source for solving problems of existing power generation methods such as thermal power generation and hydropower generation.
[0003]
As solar cell types, various types of solar cells such as crystalline solar cells, amorphous solar cells, and compound semiconductor solar cells have been researched and developed. Among them, amorphous silicon solar cells have a conversion efficiency of crystalline solar cells. However, the solar cell has excellent features that are not found in crystalline solar cells, such as being easy to increase in area, having a large light absorption coefficient, and operating with a thin film. One.
[0004]
As a structure of an amorphous silicon solar cell, for example, a structure in which a back electrode, a semiconductor layer, and a light receiving surface electrode are sequentially laminated on the surface of a conductive substrate made of stainless steel or the like is known. This light receiving surface electrode is formed of, for example, a transparent conductive oxide.
[0005]
Furthermore, a current collecting electrode made of a thin metal for collecting current is disposed on the surface of the light receiving surface electrode. Since the current collecting electrode is provided on the light incident surface side of the solar cell, the area becomes a so-called shadow loss, and the effective area contributing to the power generation of the solar cell is reduced. For this reason, the current collecting electrode is often formed in a relatively thin comb shape. That is, since the current collecting electrode is usually thin and long, it is required to select a material and to design a cross-sectional shape with a small electric resistance.
[0006]
Furthermore, an electrode called a bus bar electrode is formed on the surface of the current collecting electrode in order to collect the current collected by the current collecting electrode. The bus bar electrode is made of a thicker metal than the current collecting electrode.
[0007]
As an example of the electrode, Japanese Patent Application Laid-Open No. 08-236796 discloses a collecting electrode using a metal wire. FIG. 6 shows a schematic diagram of an example thereof.
[0008]
In FIG. 6, reference numeral 601 denotes a photovoltaic element. For example, a back electrode layer, a semiconductor layer, and a transparent electrode layer are sequentially formed on a stainless steel substrate, and 602 avoids the influence of a short circuit at the edge of the photovoltaic element. For this purpose, the transparent electrode layer is removed. Reference numeral 603 denotes a current collecting electrode, and a metal wire 604 having a diameter of 50 to 300 μm coated with a conductive paste 605 or the like is pressure-bonded onto the transparent electrode layer. Here, the conductive paste has a specific resistance of 10 due to the absence of a short circuit that leads to a decrease in output even if it directly contacts a pinhole or the like on the surface of the photovoltaic element, and the fact that metal migration does not occur. ^-1 -10 ² A carbon paste of about Ωcm or a conductive oxide paste is essential. Reference numeral 606 denotes a bus bar electrode for further current collection, which is installed for the purpose of taking out the current collected by the wire electrode 603 out of the photovoltaic element. As a material, for example, a copper foil material is used. Yes. Note that the wire electrode 603 and the bus bar electrode 606 are bonded together using a conductive paste 605 around the wire.
[0009]
[Problems to be solved by the invention]
In the above-described conventional configuration, the conversion efficiency of the solar cell is about 8 to 10%, which is a practical level. However, in recent years, the conversion efficiency of the solar cell has been remarkably improved. In particular, among the parameters that determine efficiency, a short-circuit current (so-called Isc) is improved, and a semiconductor layer (semiconductor film) exceeding 10% has been developed. As a specific value of Isc, a conventional intrinsic value is 6 to 10 mA / cm. ² Recently, 10mA / cm ² The value exceeds. However, a major problem when the current is improved is that the power generation loss at the electrode portion through which the current passes increases in proportion to the square of the current amount. In other words, even if a highly efficient semiconductor layer (semiconductor film) is made, when the generated current is taken out, the power generation loss in the portion with the large resistance becomes large, and the actual conversion efficiency of the original semiconductor layer is increased. It is a point that goes down significantly. Therefore, in the solar cell, it is necessary to appropriately consider the current collecting form according to the amount of generated current.
[0010]
Conventionally, in the current collecting form proposed in Japanese Patent Application Laid-Open No. 08-236696, the junction between the bus bar electrode and the wire electrode is formed of a material having a relatively high specific resistance such as carbon paste for the above-described reason. It was a part with high resistance. Therefore, with the improvement in the amount of current, there has been a problem that the resistance loss at the junction increases and the predetermined conversion efficiency is not achieved.
[0011]
Accordingly, an object of the present invention is to provide a photovoltaic device having a form in which the joint portion between the bus bar electrode and the wire electrode is improved in order to solve the above-described problems, and to provide a photovoltaic device with high conversion efficiency. There is. Moreover, it is providing the manufacturing method.
[0012]
[Means for Solving the Problems]
As a result of intensive research and development in order to solve the above-mentioned problems, the present inventor has found that the following photovoltaic element and its manufacturing method are optimal.
[0013]
That is, the photovoltaic element of the present invention is a photovoltaic element having a current collecting electrode made of a metal wire having a conductive coating layer and a metal bus bar connected to the current collecting electrode. The portion not covered with the conductive coating layer And the metal bus bar are formed of a conductive material having a specific resistance smaller than that of the conductive coating layer. According to such a configuration, the resistance value between the metal wire / metal bus bar can be made lower than before, the power generation loss can be reduced, and the conversion efficiency can be greatly improved as compared with the conventional electrode configuration.
[0014]
The specific resistance of the conductive material is 1/500 or less of the specific resistance of the conductive coating layer. According to such a configuration, it is possible to sufficiently suppress a decrease in conversion efficiency due to power generation loss.
[0015]
Further, the conductive material is a conductive adhesive. According to such a configuration, since it can be easily adapted to a complicated shape portion between the wire and the bus bar, stable joining is possible.
[0016]
In addition, the conductive filler constituting the conductive adhesive is mainly composed of silver, copper, or nickel. According to such a configuration, the above conditions can be easily cleared, and the resistance loss at the joint can be reduced to a negligible level.
[0017]
Moreover, the resin component which comprises the said conductive adhesive has an acrylic resin or an epoxy resin as a main component. According to this configuration, the moisture resistance stability of the joint is increased. In particular, in the case of an acrylic resin, since it has flexibility, it becomes resistant to mechanical repeated bending strength and can be used for a flexible solar cell.
[0018]
Further, the conductive material is a polymer film having conductivity in the thickness direction. According to such a configuration, it is possible to easily adapt to a complicated shape portion between the wire and the bus bar as in the case of the conductive adhesive, so that a stable joint can be formed.
[0019]
Further, the specific resistance of the conductive coating layer is from 0.1 Ωcm to 100 Ωcm. According to such a configuration, as in the conventional case, it has a sealing function against occurrence of a short circuit in the cell, and the electrical resistance loss between the transparent electrode layer provided on the surface of the photovoltaic element and the metal wire can be ignored. It can be a range.
[0020]
Further, the conductive filler constituting the conductive coating layer is carbon or graphite. According to such a configuration, the migration problem on the surface of the photovoltaic element can be suppressed as in the conventional case, and it can be used for a thin film type photovoltaic element.
[0021]
The method for producing a photovoltaic device of the present invention is the method for producing a photovoltaic device having a current collecting electrode made of a metal wire having a conductive coating layer, and a metal bus bar connected to the current collecting electrode. A step of exposing the metal wire by removing at least a part of the conductive coating layer of the collecting electrode; a step of arranging a conductive material having a specific resistance smaller than that of the conductive coating layer on the exposed portion; A step of disposing a metal bus bar at a position facing the metal wire through the conductive material; and a step of connecting the metal wire and the metal bus bar by heating or / and pressurizing the conductive material. It is characterized by having. According to this configuration, the metal wire is exposed by removing at least a part of the conductive coating layer, the conductive material having a specific resistance smaller than that of the conductive coating layer is disposed on the exposed portion, and the bus bar is further disposed on the exposed portion. Since the electrode is disposed, the resistance can be reliably and stably lowered.
[0022]
The conductive coating layer may be removed by irradiating with an energy beam. According to such a configuration, the removal of the conductive coating layer is simple, and the manufacturing method is suitable for mass production.
[0023]
Further, the conductive filler constituting the conductive coating layer is carbon or graphite. According to such a configuration, since the absorption efficiency at the time of light beam irradiation is increased, the conductive coating layer can be easily removed, and the metal wire can be reliably and efficiently exposed.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Next, exemplary embodiments of the present invention will be described in detail.
[0025]
First, the photovoltaic device of the present invention will be described in detail with reference to FIG.
[0026]
FIG. 1 is a schematic diagram showing an example of the relationship between the current collecting electrode and the bus bar electrode according to the present invention. FIG. 1 (a) is a front view of the photovoltaic element, and FIG. 1 (b) is a cross-sectional view along AA '. Yes.
[0027]
In the figure, 101 represents a photovoltaic element, and 102 represents an etching line for a transparent electrode layer provided on the surface of the photovoltaic element. Reference numeral 103 denotes a current collecting electrode. In the present invention, the metal wire 104 is coated around the conductive coating layer 105. Reference numeral 106 denotes a metal bus bar, and a conductive material 107 having a specific resistance smaller than that of the conductive coating layer 105 is disposed at a connection portion between the metal bus bar 106 and the metal wire 104. The presence of the conductive material 107 can reduce the resistance between the metal wire 104 and the metal bus bar 106. Reference numeral 108 denotes an insulating member for insulating the metal wire 104 and the photovoltaic device 101 in a region outside the etching line 102 of the transparent electrode layer.
[0028]
Below, explanation is added for each item.
[0029]
(Collector electrode)
Examples of the collecting electrode according to the present invention include those shown in FIGS. 2 and 3. The current collecting electrode in FIG. 2 is a case where the metal wire 201 is coated with one type of conductive coating layer 202. The current collecting electrode in FIG. 3 is a case where the metal wire 301 is coated with two types of conductive coating layers, that is, a first coating layer 302 and a second coating layer 303.
[0030]
It is preferable that the metal wires 201 and 301 are industrially stably supplied as wires. Further, the material of the metal wires 201 and 301 has a specific resistance of 10 ^-Four It is desirable to use a metal of Ωcm or less. For example, materials such as copper, silver, gold, platinum, aluminum, molybdenum, and tungsten are preferably used because of their low electric resistance. Of these, copper, silver, and gold are preferable because of their low electrical resistance. The metal wire may be an alloy of these.
[0031]
Furthermore, if desired, a thin metal layer may be formed on the surface of the metal wire for the purpose of preventing corrosion, preventing oxidation, improving adhesion with a conductive resin, improving electrical conduction, and the like. Examples of the metal layer provided on the surface of the metal wire include silver, palladium, alloys of silver and palladium, noble metals that are not easily corroded such as gold, and metals having good corrosion resistance such as nickel and tin. Among them, gold, silver, and tin are less susceptible to humidity and the like, and thus are preferably used as a metal layer. As a method for forming the metal layer provided on the surface of the metal wire, for example, a plating method or a cladding method is preferably used.
[0032]
The cross-sectional shape of the metal wire may be circular or rectangular, and is appropriately selected as desired. The diameter of the metal wire is a value selected by designing so that the sum of the electrical resistance loss and the shadow loss is minimized. Specifically, for example, a copper wire having a diameter of 25 μm to 1 mm for an enameled wire shown in JIS-C-3202 is preferably used. More preferably, a photovoltaic element with good photoelectric conversion efficiency can be obtained by setting the diameter to 25 μm to 200 μm. If the thickness is smaller than 25 μm, the wire is easily cut and difficult to manufacture, and the electrical loss increases. In the case of 200 μm or more, the shadow loss increases, or the unevenness of the surface of the photovoltaic element increases, and the filler such as EVA (ethylene vinyl acetate) used for the surface coating layer must be thickened. Disappear.
[0033]
The metal wire is formed by molding to a desired diameter using a known wire drawing machine. The metal wire that has passed through the wire drawing machine is hard, but the easiness of elongation, the easiness of bending, etc. may be annealed by a known method according to desired characteristics and used soft.
[0034]
A conductive coating layer 202 shown in FIG. 2 is a single-layer coating layer, and is formed of a thermosetting conductive adhesive or a thermoplastic conductive adhesive. These have a function of mechanically and electrically connecting the collector electrode body and the photovoltaic element substrate by a thermocompression bonding process.
[0035]
On the other hand, the conductive coating layer shown in FIG. 3 is a two-layer coating layer, and includes a first coating layer 302 and a second coating layer 303. The first covering layer 302 is formed of a thermosetting conductive adhesive, and protects the metal wire 301 and performs mechanical and electrical connection. Further, it has a function of preventing migration due to the metal wire 301 and suppressing a current flowing from the current collecting electrode to a defective portion of the photovoltaic element. The second covering layer 303 is also formed of a thermosetting conductive adhesive, and has a function of mechanically and electrically connecting the collector electrode body and the photovoltaic element substrate by a thermocompression bonding process. It is preferable that the conductive adhesive constituting the second coating layer 303 is left in an uncured state after coating, and is subjected to a curing treatment after an adhesion process.
[0036]
The conductive coating layers 202, 302, and 303 are made of a conductive adhesive, and are obtained by dispersing conductive particles and a polymer resin. The specific resistance of these conductive adhesives is a resistance that can be ignored to collect the current generated by the photovoltaic element, and it is necessary to have an appropriate resistance value so that no shunt is generated. Specifically, about 0.1 Ωcm or more and 100 Ωcm or less is preferable. This is because the shunt prevention function decreases when the resistance is less than 0.1 Ωcm, and the electrical resistance loss increases when the resistance is greater than 100 Ωcm.
[0037]
The conductive particles are pigments for imparting conductivity, and examples of the material include carbon black, graphite and In ₂ O _Three , TiO ₂ , SnO ₂ , ITO, ZnO, and oxide semiconductor materials obtained by adding appropriate dopants to the above materials are preferably used. Since these materials have low migration properties, they can be used, for example, in solar cells having a thin film semiconductor layer. In particular, when carbon black and graphite are used as the conductive particles, the adhesive itself is blackened, so that the absorption of the light beam in the manufacturing process described later is improved, and the exposure of the metal wire is facilitated. Is preferred.
[0038]
The particle size of the conductive particles needs to be smaller than the thickness of the coating layer to be formed. However, if the particle size is too small, the resistance at the contact point between the particles increases, and a desired specific resistance cannot be obtained. From such circumstances, the average particle size of the conductive particles is preferably 0.02 μm or more and 15 μm or less. Further, two or more different kinds of conductive particles may be mixed to adjust the specific resistance and the degree of dispersion in the conductive resin.
[0039]
The conductive particles and the polymer resin are mixed at a suitable ratio in order to obtain a desired specific resistance. However, when the conductive particles are increased, the specific resistance is lowered, but the ratio of the resin is reduced, so that the coating film is reduced. The stability of becomes worse. Further, when the polymer resin is increased, the contact between the conductive particles becomes poor and the resistance is increased. Therefore, a good ratio is appropriately selected depending on the polymer resin to be used, conductive particles, and desired physical property values. Specifically, a favorable specific resistance can be obtained by setting the conductive particles to about 5% to 95% by volume.
[0040]
As the polymer resin, a resin that is easy to form a coating on a metal wire, has excellent workability, has flexibility, and has excellent weather resistance is preferable. Examples of the polymer resin having such characteristics include a thermosetting resin and a thermoplastic resin.
[0041]
As the thermosetting resin, for example, urethane, epoxy, phenol, polyvinyl formal, alkyd resin, or a resin obtained by modifying these may be used as a suitable material. In particular, urethane resins, epoxy resins, and phenol resins are used as insulating coating materials for enameled wires, and are excellent materials in terms of flexibility and productivity. Moreover, it is also suitably used as a current collecting electrode material for photovoltaic elements in terms of moisture resistance and adhesiveness.
[0042]
Examples of suitable thermoplastic resins include butyral, phenoxy, polyamide, polyamideimide, melamine, acrylic, styrene, polyester, and fluorine. In particular, butyral resin, phenoxy resin, polyamide resin, and polyamideimide resin are excellent materials in terms of flexibility, moisture resistance, and adhesiveness, and are preferably used as a material for a collecting electrode of a photovoltaic element.
[0043]
In the conductive adhesive, for example, an additive such as a coupling agent may be mixed for the purpose of improving adhesion to a metal.
[0044]
The thickness of the conductive coating layer may be selected as appropriate, but is preferably in the range of 5 μm to 30 μm. When the thickness is less than 5 μm, it is difficult to coat uniformly and pinholes are likely to occur, and at the same time, the function as an adhesive layer may be insufficient. On the other hand, when the thickness is 30 μm or more, the shadow loss becomes extremely large. Therefore, about 5 to 30 μm is preferable.
[0045]
(Metal bus bar)
The metal bus bar 106 according to the present invention is a current collector for collecting current flowing through the current collecting electrode 103 at one end. From this point of view, the material used for the metal bus bar is preferably a material having a low specific resistance and being supplied industrially stably.
[0046]
As such a material, workable and inexpensive copper is preferably used. When copper is used, a thin metal layer may be provided on the surface for the purpose of preventing corrosion, preventing oxidation, and the like. As the surface metal layer, for example, silver, palladium, an alloy of palladium and silver, or a precious metal that is not easily corroded such as gold, or a metal having good corrosion resistance such as nickel, solder, or tin is preferably used. As a method for forming the surface metal layer, for example, a vapor deposition method, a plating method, and a cladding method, which are relatively easy to create, are preferably used.
[0047]
The thickness of the metal bus bar is preferably 50 μm or more and 200 μm or less. By setting the thickness to 50 μm or more, it is possible to ensure a sufficient cross-sectional area that can sufficiently correspond to the generated current density of the photovoltaic element, and it can be used substantially as a mechanical coupling member. On the other hand, the thicker the metal bus bar, the smaller the resistance loss. However, when the metal bus bar is 200 μm or less, the surface coating material can be smoothly coated.
[0048]
Any number of metal bus bars may be provided depending on the form of the photovoltaic element, and the number is not particularly limited to one. The metal bus bar used here preferably has a length approximately the same as the size of the photovoltaic element to be provided. There is no restriction | limiting in particular also about a shape, A foil shape, a column shape, etc. can be used.
[0049]
(Conductive material)
The conductive material 107 is disposed between the metal wire 104 and the metal bus bar 106 and functions as a path for a current flowing from the metal wire into the metal bus bar, and at the same time has a mechanical bonding function. Therefore, it is preferable that the resistance is very low and the adhesion to metal is good.
[0050]
The specific resistance of the conductive material must be such that the power loss is negligible when current flows from the wire, and is required to be lower than the conductive coating layer. . In order to make the power loss negligible, an effect can be obtained by setting the specific resistance of the conductive material to 1/500 or less of the specific resistance of the conductive coating layer. The specific specific resistance of the conductive material is 1 × 10 ^-Five Ωcm or more 1 × 10 ^-3 It is preferably about Ωcm or less.
[0051]
The conductive material 107 is preferably provided in all regions connecting the metal wire and the metal bus bar, because it has the lowest resistance. However, even if it is provided only in a part of the region, the effect is produced.
[0052]
Various materials can be used as the conductive material satisfying the above conditions, and a conductive adhesive or a polymer film having conductivity in the thickness direction (so-called anisotropic conductive film) is particularly desirable. When these materials are used, they can be arranged well in a complicated shape portion between the metal wire and the metal bus bar, so that stable low-resistance bonding is possible.
[0053]
When the conductive material 107 is a conductive adhesive, it can be obtained by dispersing conductive particles and a polymer resin in a desired ratio, like the conductive coating layer.
[0054]
The conductive particle is not particularly limited as long as it can realize the above specific resistance, and a normal metal filler mainly composed of gold, silver, copper, nickel or the like can be used. Of these, silver, copper, and nickel are preferred as the main component for the purpose of reducing the specific resistance as much as possible and cost.
[0055]
Further, as the resin component, as described above, it is preferable to use, for example, urethane, epoxy, phenol, butyral, acrylic, polyester, etc., as a resin having excellent adhesion to metal as described above and excellent weather resistance and moisture resistance. As a material. In particular, an epoxy resin and an acrylic resin are preferable from the experimental results regarding the moisture resistance of the present inventor, but an acrylic resin is a more preferable material from the viewpoint of flexibility.
[0056]
In the conductive adhesive, for example, an additive such as a coupling agent may be mixed for the purpose of improving adhesion to a metal.
[0057]
In addition, even when the conductive material 107 is an anisotropic conductive film, it is possible to provide a joint having excellent stability, like the conductive adhesive.
[0058]
(Photovoltaic element)
Since the present invention is an invention relating to the joining form of the current collecting electrode and the bus bar portion, the photovoltaic device in the present invention is not particularly limited, and is a single crystal, a thin film single crystal, a polycrystal, a thin film polycrystal, an amorphous In addition to being applicable to silicon solar cells, the present invention can also be applied to solar cells using semiconductors other than silicon and Schottky solar cells.
[0059]
From the viewpoint of current, the solar cell having any current density has a considerable effect. In particular, the intrinsic Isc is 10 mA / cm. ² The effect is large with respect to the above solar cell.
[0060]
Here, as a representative example, an amorphous silicon solar cell in which a metal wire is often used as a collecting electrode will be described in detail. A cross-sectional view thereof is shown in FIG.
[0061]
FIG. 4 is a schematic cross-sectional view of an amorphous silicon solar cell of a type in which light is incident from the surface opposite to the substrate. In the figure, 401 is a substrate, 402 is a lower electrode, 403, 413 and 423 are n-type semiconductor layers, 404, 414 and 424 are i-type semiconductor layers, 405, 415 and 425 are p-type semiconductor layers, and 406 is a transparent conductive film. An upper electrode 407 is a grid electrode for which a collecting electrode is used.
[0062]
In the case of a thin-film solar cell such as amorphous silicon, the substrate 401 is a member that mechanically supports the semiconductor layer and is also used as an electrode. Therefore, the substrate 401 is required to have heat resistance that can withstand the heating temperature when the semiconductor layer is formed, but may be conductive or electrically insulating.
[0063]
Examples of conductive materials include metals such as Fe, Ni, Cr, Al, Mo, Au, Nb, Ta, V, Ti, Pt, and Pb, or alloys thereof such as thin plates such as brass and stainless steel, and composites thereof. Examples include bodies, carbon sheets, and galvanized steel sheets. In addition, as an electrically insulating material, a heat-resistant synthetic resin film or sheet such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, epoxy or the like and glass fiber , Carbon fibers, boron fibers, composites with metal fibers, etc., and metal thin films and / or SiO of different materials on the surfaces of these metal thin plates, resin sheets, etc. ₂ , Si _Three N _Four , Al ₂ O _Three , AlN and other insulating thin films subjected to surface coating treatment by sputtering, vapor deposition, plating, etc., and glass, ceramics and the like.
[0064]
The lower electrode 402 is one electrode for taking out the electric power generated in the semiconductor layers 403, 404, 405, 413, 414, 415, 423, 424, and 425, and works to be in ohmic contact with the semiconductor layer 403. It is required to have a function. Examples of the material include Al, Ag, Pt, Au, Ni, Ti, Mo, W, Fe, V, Cr, Cu, Nichrome, SnO. ₂ , In ₂ O _Three So-called metal bodies or alloys such as ZnO and ITO, and transparent conductive oxide (TCO) are used. The surface of the lower electrode is preferably smooth, but may be textured when causing irregular reflection of light. Further, when the substrate 401 is conductive, the lower electrode 402 is not necessarily provided. The lower electrode 402 can be formed by a known method such as plating, vapor deposition, or sputtering.
[0065]
The amorphous silicon semiconductor layer is not only a single configuration (FIG. 4A) having a set of n layer 403, i layer 404, and p layer 405, but also a double configuration in which two or three pin junctions or pn junctions are stacked. (FIG. 4B) and triple configuration (FIG. 4C) are also preferably used. In particular, as a semiconductor material constituting the i layer 404, 414, 424, in addition to a-Si, so-called group IV and group IV alloy amorphous semiconductors such as a-SiGe and a-SiC can be cited. As a method for forming the amorphous silicon semiconductor layer, for example, a known method such as an evaporation method, a sputtering method, a high-frequency plasma CVD method, a microplasma CVD method, an ECR method, a thermal CVD method, or an LPCVD method is used as desired. As the film forming apparatus, a batch type apparatus or a continuous film forming apparatus can be used as desired.
[0066]
The transparent conductive film 406 is necessary when the sheet resistance is high like amorphous silicon, and needs to be transparent because it is located on the light incident side. As a material of the transparent conductive film 406, for example, SnO ₂ , In ₂ O _Three , ZnO, CdO, CdSnO _Four , And metal oxides such as ITO.
[0067]
(Production method)
Next, a manufacturing method of an example of the photovoltaic element will be described with reference to FIGS.
FIGS. 5A to 5F are front views when the photovoltaic element is viewed from the light incident side.
[0068]
(A) The above-described photovoltaic element 501 is prepared in an arbitrary size.
[0069]
(B) A line (so-called etching line) 502 from which the transparent conductive film located on the outermost surface is removed is formed. This is a process to prevent the short circuit area around the photovoltaic element from affecting the element efficiency, and when there is no short circuit area or the degree of short circuit can be ignored. Need not be provided.
[0070]
In addition, an insulating member 503 such as a double-sided adhesive tape is disposed at the end of the photovoltaic element 501. The insulating member 503 is disposed for the purpose of preventing the current collecting electrode or the metal bus bar from coming into contact with the short-circuit portion of the photovoltaic element 501 and short-circuiting, and there is no danger of short-circuiting. It is not necessary to provide the same as the etching line.
[0071]
(C) Next, current collecting electrodes 504 made of a metal wire having a conductive coating layer are placed on the transparent conductive layer at an appropriate pitch interval. At this time, the current collecting electrode 504 is fixed only on the insulating member 504 at the end of the photovoltaic element.
[0072]
(D) The conductive coating layer at a position where the metal bus bar is placed in a subsequent process is removed, and the metal wire is exposed (505 parts). The removal method is not particularly limited, for example, the conductive coating layer may be mechanically scraped off or may be removed by chemical treatment. However, a method of irradiating the removal part with an energy beam is preferable as a method for obtaining a good production yield and obtaining a tact. That is, this is a method of removing the coating layer by irradiating the coating layer with an energy beam to raise the temperature of the coating layer and evaporating it by heating. Here, the energy beam is an electron beam, an ion beam, a laser, or the like, and a laser is preferable from the viewpoint of simplifying the apparatus. In the case of using a laser, if the conductive filler constituting the conductive coating layer is carbon or graphite, the laser is well absorbed and can be removed easily and reliably. Among them, the conductive filler is carbon or graphite, and the laser is preferably a YAG laser.
[0073]
The removal step can be performed on the photovoltaic element as shown in FIG. 5, but it is also possible to attach the wire previously removed at another place on the photovoltaic element.
[0074]
(E) The conductive material 506 is placed on the portion 505 where the metal wire is exposed. When the conductive material is a conductive adhesive, it can be placed using a known method such as a dispenser, stamp, or screen printing. The conductive adhesive may be placed in the form of dots, or may be placed in a line that intersects with the collecting electrode 505.
As for the amount of conductive adhesive, if it is small, the adhesive strength is insufficient and it becomes very unstable, and if it is large, it will protrude to the active area of the cell when the metal bus bar is placed Although it selects suitably from balance, when arrange | positioning at dotted | punctate form, about 0.1 mg-10 mg per point are suitable.
[0075]
When the conductive material is an anisotropic conductive film, the conductive material can be placed so as to intersect the exposed portion 505.
[0076]
(F) A metal bus bar 507 is disposed at a position where the conductive material 506 is disposed, and heat curing is performed at a desired temperature. At this time, the entire surface of the photovoltaic element may be heated, and the conductive coating layer is cured to fix the metal wire on the transparent conductive layer. At the same time, the conductive material 506 is also cured, so that the metal bus bar 507 and the metal wire are bonded. Adhere and fix.
[0077]
Moreover, it is desirable to pressurize the entire surface of the photovoltaic element simultaneously with the heating step. By applying pressure, the adhesive force of the metal wire on the transparent conductive layer is improved and the reliability is improved, and at the same time, the distance between the metal wire and the metal bus bar is reduced by pressing the conductive material, The resistance value can be further reduced.
The pressure is preferably a pressure at which the conductive material 506 and the conductive coating layer are appropriately deformed, and should be a pressure that does not destroy the photovoltaic element. Specifically, for example, 1.1 × 10 ^Five Pa to 6.0 × 10 ^Five A degree of Pa is preferred.
[0078]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples.
[0079]
(Create current collecting electrode)
Below, the current collection electrode used by the Example and the comparative example is demonstrated.
[0080]
First, a current collecting electrode was prepared in which two conductive coating layers were coated around a metal wire as shown in FIG.
[0081]
As the metal wire 301, a silver clad copper wire having a diameter of 100 μm (a silver clad with a thickness of 2 μm around a diameter of 98 μm) was prepared.
[0082]
Next, as the first coating layer 302, a carbon-containing urethane resin paste (manufactured in-house, specific resistance at curing 0.5 Ωcm) was applied around the wire in a thickness of 5 μm ± 1 μm. About the 1st coating layer, the perfect cured film was created by passing the history of 280 ° C for 1 minute which is standard hardening conditions in IR oven after application.
[0083]
Next, the second coating layer 303 was formed using the same carbon-containing urethane resin paste. The second coating layer was applied at a thickness of 20 μm ± 1 μm and dried under the condition of 120 ° C. for 1 minute.
[0084]
This condition is equal to or lower than the dissociation temperature of the curing agent present in the paste, and the second coating layer is simply in a state where the solvent is volatilized and tack is eliminated.
[0085]
In this way, a current collecting electrode having a diameter of about 150 μm was prepared.
[0086]
Example 1
In this example, an amorphous solar cell A having a pin junction type triple configuration with a layer configuration shown in FIG.
[0087]
First, a sufficiently degreased and cleaned SUS430BA substrate 401 was placed in a DC sputtering apparatus (not shown) to deposit 450 nm of Ag, and then 1000 nm of ZnO was deposited to form the lower electrode 402. The substrate was taken out and placed in a microwave plasma CVD film forming apparatus (not shown), and a bottom layer was formed in this order: a silicon layer as the n layer 403, a silicon germanium layer as the i layer 404, and a silicon layer as the p layer 405. Next, in the same manner, a middle layer is sequentially formed in the order of a silicon layer on the n layer 413, a silicon germanium layer on the i layer 414, and a silicon layer on the p layer 415. Further, an n layer 423, an i layer 424, and a p layer 425 are formed. In this order, the top layer of the silicon layer was formed, and the semiconductor layer was deposited. Thereafter, ITO was deposited to a thickness of 70 nm as a transparent conductive film 406 having a function also serving as an antireflection effect by placing in a sputtering apparatus (not shown).
[0088]
Next, the solar cell substrate 401 has a size of 30 × 30 cm and an effective cell area of 900 cm. ² Then, an unnecessary portion of the transparent conductive film was removed using an etching paste mainly composed of ferric chloride and a commercially available printing machine.
[0089]
Next, an insulating member 503 as shown in FIG. 5B was provided outside the effective area and at the two opposing sides. The insulating member 503 was formed by applying a polyimide base double-sided adhesive tape having a thickness of 100 μm.
[0090]
Next, the current collecting electrode wire was cut into a length of about 30 cm and placed as shown in FIG. The collector electrode wires were placed at intervals of 5 mm, and both end portions thereof were fixed by the adhesive force of the adhesive tape.
[0091]
Then, as shown in FIG.5 (d), a laser beam is irradiated from right above the collector electrode wire 504 which exists on the insulating member 503, the coating layer of a wire is removed only 2 mm long, and a silver clad copper wire is exposed. It was. At this time, a Q-switched YAG laser was used as the laser.
[0092]
Next, a fluororesin paste containing carbon (manufactured by our company, specific resistance at curing 0.1 Ωcm) was applied with a dispenser to the portion 505 where the silver clad copper wire was exposed. The dotting amount was adjusted by adjusting the conditions of the dispenser so as to be about 1 mg per place.
[0093]
Further, a metal bus bar 507 was placed in parallel with the double-sided pressure-sensitive adhesive tape from above the part subjected to the dotting as shown in FIG. As the metal bus bar, silver-plated copper having a thickness of 100 μm was used. In this state, by heat-pressing the whole with a heating device (not shown), the collector electrode wire is adhered and fixed on the ITO within the effective area, and the carbon paste that has been deposited in the metal bus bar portion is cured, The bus bar and the wire could be bonded and fixed. The heating condition is 200 ° C., 45 seconds, and the pressure is about 2 × 10 ^Five Performed at Pa. Five solar cells A were completed through the above steps.
[0094]
The completed solar cell A is 100mW / cm in the AM1.5 global solar spectrum. ² When the solar cell characteristics were measured using a pseudo solar light source (hereinafter referred to as a simulator) with a light quantity of 2 and the effective conversion efficiency was determined, the average was 12.9%, which was a good characteristic and there was little variation.
[0095]
Furthermore, when the resistance between the metal wire / metal bus bar of the produced solar cell A was measured with a four-terminal resistance measuring device (not shown) and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency was 0. It was equivalent to 94%.
[0096]
(Comparative Example 1)
In Comparative Example 1, an amorphous solar cell A ′ having a pin junction type triple configuration with the layer configuration shown in FIG. Comparative Example 1 is different from Example 1 only in that there is no step of removing the covering layer of the collecting electrode with a laser and a step of placing the conductive paste, and the connection between the metal wire and the metal bus bar is different. Is performed with a conductive coating around the metal wire. The procedure is described below.
[0097]
First, a sufficiently degreased and cleaned SUS430BA substrate 401 was placed in a DC sputtering apparatus (not shown) to deposit 450 nm of Ag, and then 1000 nm of ZnO was deposited to form the lower electrode 402. The substrate was taken out and placed in a microwave plasma CVD film forming apparatus (not shown), and a bottom layer was formed in this order: a silicon layer as the n layer 403, a silicon germanium layer as the i layer 404, and a silicon layer as the p layer 405. Next, in the same manner, a middle layer is sequentially formed in the order of a silicon layer on the n layer 413, a silicon germanium layer on the i layer 414, and a silicon layer on the p layer 415. Further, an n layer 423, an i layer 424, and a p layer 425 are formed. In this order, the top layer of the silicon layer was formed, and the semiconductor layer was deposited. Thereafter, ITO was deposited to a thickness of 70 nm as a transparent conductive film 406 having a function also serving as an antireflection effect by placing in a sputtering apparatus (not shown). Next, the solar cell substrate 401 has a size of 30 × 30 cm and an effective cell area of 900 cm. ² Then, an unnecessary portion of the transparent conductive film was removed using an etching paste mainly composed of ferric chloride and a commercially available printing machine.
[0098]
Next, an insulating member 503 as shown in FIG. 5B was provided outside the effective area and at the two opposing sides. The insulating member 503 was formed by applying a polyimide base double-sided adhesive tape having a thickness of 100 μm.
[0099]
Next, the current collecting electrode wire was cut into a length of about 30 cm and placed as shown in FIG. The collector electrode wires were placed at intervals of 5 mm, and both end portions thereof were fixed by the adhesive force of the adhesive tape.
[0100]
Further, a metal bus bar was placed on the fixed wire in parallel with the double-sided adhesive tape as shown in FIG. As the metal bus bar, silver-plated copper having a thickness of 100 μm was used. In this state, the entire electrode is heat-pressed with a heating device (not shown) to adhere and fix the current collecting electrode wire on the ITO within the effective area, and the second coating layer is cured even in the metal bus bar portion. The bus bar and the wire could be bonded and fixed. The heating conditions are 200 ° C. and 45 seconds, and the pressure is about 2.0 × 10 ^Five Performed at Pa. Five solar cells A ′ were completed through the above steps.
[0101]
When the solar cell characteristics of the completed solar cell A ′ were measured using a simulator and the effective conversion efficiency was determined, the average was 12.4%.
[0102]
Furthermore, when the resistance between the metal wire / metal bus bar of the created solar cell A ′ was measured with a four-terminal resistance measuring device (not shown), and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency was It was equivalent to 4.69%.
[0103]
Comparing Example 1 and Comparative Example 1, it is clear that Example 1 has an effective conversion efficiency improved by 0.5%, and the cause is due to the loss between the wires / bus bars. Therefore, it was found that the electrode configuration of the present invention has very good initial efficiency characteristics.
[0104]
(Example 2)
In Example 2, five amorphous solar cells B having a pin junction type triple structure having the layer structure shown in FIG.
[0105]
The solar cell B was prepared in the same manner as in Example 1 except that it was prepared using an epoxy-based copper paste (specific resistance at curing 0.001 Ωcm) as a conductive adhesive to be coated.
[0106]
The solar cell characteristics of the completed solar cell B were measured using a simulator, and the effective conversion efficiency was determined. As a result, the average of 13.0% was a good characteristic and there was little variation.
[0107]
Furthermore, when the resistance between the metal wire / metal bus bar of the produced solar cell B was measured with a four-terminal resistance measuring device (not shown) and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency of 0 was obtained. It was equivalent to 0.01%. It became clear that the power generation loss was almost negligible by using a conductive adhesive having a specific resistance of about 0.001Ω.
[0108]
(Example 3)
In Example 3, five amorphous solar cells C having a pin junction triple structure having the layer structure shown in FIG.
[0109]
The solar cell C was prepared in exactly the same manner as in Example 1 except that it was prepared using an epoxy-based silver paste (specific resistance at curing 0.0001 Ωcm) as a conductive adhesive to be applied.
[0110]
When the solar cell characteristics of the completed solar cell C were measured using a simulator and the effective conversion efficiency was determined, the average was 13.0%, which was a good characteristic and there was little variation.
[0111]
Furthermore, when the resistance between the metal wire / metal bus bar of the produced solar cell C was measured with a four-terminal resistance measuring device (not shown), and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency was 0. .01% or less.
[0112]
In this example, a conductive adhesive having an resistivity one digit lower than that in Example 2 was used, but the effective conversion efficiency was the same. That is, it was revealed that sufficient conversion efficiency can be achieved in a region where the specific resistance of the conductive adhesive does not contribute.
[0113]
Example 4
In Example 4, five amorphous solar cells D having a pin junction triple structure with the layer structure shown in FIG.
[0114]
The solar cell D was prepared in the same manner as in Example 1 except that it was prepared using an acrylic silver paste (specific resistance at curing 0.0001 Ωcm) as a conductive adhesive to be coated.
[0115]
When the solar cell characteristics of the completed solar cell D were measured using a simulator and the effective conversion efficiency was obtained, the average was 13.0%, which was a good characteristic and there was little variation.
[0116]
Furthermore, when the resistance between the metal wire / metal bus bar of the produced solar cell D was measured with a four-terminal resistance measuring device (not shown), and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency was 0. .01% or less.
[0117]
In this example, a conductive adhesive having a specific resistance lower by one digit than that of Example 2 was used as in Example 3, but the effective conversion efficiency was the same. That is, it was revealed that sufficient conversion efficiency can be achieved in a region where the specific resistance of the conductive adhesive does not contribute.
[0118]
(Example 5)
The fifth embodiment is different from the other embodiments in that an anisotropic conductive film is used as a conductive material, and the amorphous solar cell E having a pin junction type triple structure in the layer structure shown in FIG. Created.
[0119]
Up to the step of removing the wire covering layer shown in FIG. Thereafter, an anisotropic conductive film (thickness 25 μm, specific resistance at crimping 0.001Ω (calculated value)) is cut into an appropriate size and placed on the exposed portion of the silver-clad copper wire. A metal bus bar was placed as shown in FIG. As the metal bus bar, silver-plated copper having a thickness of 100 μm was used. In this state, first, only the top of the metal bus bar is attached by a thermocompression bonding apparatus shown in the figure at 180 ° C. for 20 seconds and a pressure of about 4.1 × 10. ⁶ Thermocompression bonding was performed under Pa conditions. After that, further 200 ° C 45 seconds, pressure about 2.0 × 10 ^Five The entire collector electrode wire was bonded and fixed on ITO by thermocompression bonding under the conditions of Pa.
[0120]
Five solar cells E were completed by the above process.
[0121]
When the solar cell characteristics of the completed solar cell E were measured using a simulator and the effective conversion efficiency was determined, the average efficiency was 13.0%, and there was little variation.
[0122]
Furthermore, when the resistance between the metal wire and the metal bus bar of the produced solar cell E was measured with a four-terminal resistance measuring device (not shown), and the amount of power generation loss at the connection portion was simulated from the measured value, the intrinsic conversion efficiency was 0. It was equivalent to 0.01%.
[0123]
In this example, the case where an anisotropic conductive film is used as the conductive material has been described in detail, but it has become clear that the same conversion efficiency as that of the conductive adhesive can be achieved.
[0124]
(Comparative Experiment 1)
Resin coating (lamination) was performed on the solar cells A to E created in the above examples in order to perform an evaluation test described later. The procedure is shown below.
[0125]
Solar cell, EVA (ethylene-vinyl acetate copolymer) sheet (thickness 460 μm), unstretched ETFE (polyethylene tetrafluoroethylene) film (thickness 50 μm), polyethylene terephthalate (PET) film 50 μm thick), organic nonwoven fabric, and galvalume steel plate (thickness 0.4 mm) were stacked in the order of ETFE / EVA / organic nonwoven fabric / solar cell / EVA / PET / EVA / steel plate to form a solar cell module laminate. Next, a stainless steel mesh (40 × 40 mesh, wire diameter 0.15 mm) is placed outside the ETFE via a Teflon film for release (thickness 50 μm), and the laminate is pressed using a vacuum laminator. A solar cell was completed by thermocompression bonding at 150 ° C. for 30 minutes while degassing.
[0126]
On the surface of the surface covering material, irregularities with a height difference of up to 30 μm were formed by a mesh.
[0127]
The output terminal was previously turned to the back side of the photovoltaic element, and after lamination, the output could be taken out from the terminal outlet that had been opened in advance in the Galvalume steel plate.
[0128]
The following comparative experiments were performed on the solar cell modules A to E thus created, assuming actual outdoor environmental conditions. Test {circle around (1)} is a test assuming the intrusion of moisture outdoors, and Test {circle around (2)} is a test assuming the influence of bending due to wind outdoors. Of the five solar cells prepared, three were used for test (1) and two for test (2).
(1) High temperature and high humidity (HH) test
A high-temperature and high-humidity test (85 ° C. and 85%) based on IEEE standard draft 9 was conducted for 1000 hours. After the test, the conversion efficiency was measured again.
(2) Dynamic load test
A dynamic load test based on IEEE standard draft 9 was performed for 10,000 cycles. After the test, the conversion efficiency was measured again. Moreover, regarding the solar cell modules A to D, after the measurement, the surface covering material and the metal bus bar were carefully removed, and the state of the conductive adhesive was observed with a microscope.
[0129]
The test results are shown in Table 1.
[0130]
[Table 1]

[0131]
Regarding the high-temperature and high-humidity test, there was almost no change in any of the modules, but only the solar cell module A showed a slight decrease, which is considered to be an influence of the resin type of the conductive adhesive.
[0132]
In addition, regarding the dynamic load test, the conversion efficiency was not deteriorated at all in any module, and it was good. In modules A, B, and C, the conductive adhesive was cracked. This result is considered to be a phenomenon caused by the flexibility of the conductive adhesive used.
[0133]
From the above results, it was found that the configuration of the present invention has sufficient reliability. In particular, it has been found that the system using an epoxy resin or an acrylic resin is particularly reliable.
[0134]
【The invention's effect】
As described above, the current collecting mode has been improved by the present invention, and it has become possible to greatly reduce the resistance loss between the bus bar and the wire part, which has been a conventional problem. In addition, it was possible to obtain a photovoltaic device with very high initial conversion efficiency. Furthermore, in the manufacturing method of these photovoltaic elements, the manufacturing method excellent in productivity, cost, and ease was able to be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of a photovoltaic device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a current collecting electrode according to the present invention.
FIG. 3 is a schematic schematic view of a current collecting electrode according to the present invention.
FIG. 4 is a cross-sectional view schematically showing a configuration of an amorphous silicon solar cell according to the present invention.
FIG. 5 is a schematic view for explaining a method for producing a photovoltaic element of the present invention.
FIG. 6 is a schematic view of a conventional photovoltaic device.
[Explanation of symbols]
101, 501, 601 Photovoltaic element
102, 502, 602 Etching line
103, 407, 504, 603 Current collecting electrode
104, 201, 301, 604 Metal wire
105, 202, 605 conductive coating layer
106, 507, 606 metal bus bar
107,506 Conductive material
108, 503, 607 Insulating member
302 1st coating layer
303 Second coating layer
401 substrate
402 Lower electrode
403, 413, 423 n-type semiconductor layer
404, 414, 424 i-type semiconductor layer
405, 415, 425 p-type semiconductor layer
406 Upper electrode
505 Covering layer removal section

Claims (11)

In a photovoltaic device having a current collecting electrode made of a metal wire having a conductive coating layer, and a metal bus bar connected to the current collecting electrode,
The connection part between the part which is not covered with the said conductive coating layer of the said metal wire , and the said metal bus bar is formed with the electrically conductive material whose specific resistance is smaller than the said conductive coating layer, The light characterized by the above-mentioned. Electromotive force element. 2. The photovoltaic element according to claim 1, wherein a specific resistance of the conductive material is 1/500 or less of a specific resistance of the conductive coating layer. The photovoltaic element according to claim 1, wherein the conductive material is a conductive adhesive. The photovoltaic element according to claim 3, wherein the conductive filler constituting the conductive adhesive contains silver, copper, or nickel as a main component. The photovoltaic element according to claim 3 or 4, wherein the resin component constituting the conductive adhesive is mainly composed of an acrylic resin or an epoxy resin. The photovoltaic element according to claim 1, wherein the conductive material is a polymer film having conductivity in a thickness direction. 7. The photovoltaic element according to claim 1, wherein a specific resistance of the conductive coating layer is 0.1 Ωcm or more and 100 Ωcm or less. The photovoltaic element according to any one of claims 1 to 7, wherein the conductive filler constituting the conductive coating layer is carbon or graphite. In the method of manufacturing a photovoltaic device having a current collecting electrode made of a metal wire having a conductive coating layer and a metal bus bar connected to the current collecting electrode, at least one of the conductive coating layers of the current collecting electrode. A step of exposing the metal wire by removing a portion, a step of disposing a conductive material having a specific resistance smaller than that of the conductive coating layer on the exposed portion, and facing the metal wire through the conductive material And a step of arranging a metal bus bar at a position and a step of connecting the metal wire and the metal bus bar by heating or / and pressurizing the conductive material. Method. The method for manufacturing a photovoltaic element according to claim 9, wherein the conductive coating layer is removed by irradiation with an energy beam. The method for manufacturing a photovoltaic element according to claim 9 or 10, wherein the conductive filler constituting the conductive coating layer is carbon or graphite.

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