JP2014241335A - Solar battery cell and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery cell and a solar battery module which are arranged to be able to prevent the delamination of a tab line while sufficiently ensuring a current collection efficiency.SOLUTION: A solar battery cell 2 comprises a substrate 11 and a backside electrode 14 formed by an aluminum layer 21. The aluminum layer has a thin part S forming a region P to provide a tab line 3 in. With this arrangement, when connecting a tab line 3 to the backside electrode 14 through an adhesive layer 22, it is possible to allow an adhesive component of the adhesive layer 22 to intrude into the thin aluminum layer 21 sufficiently. The reinforcement of the bonding between the aluminum layer 21 and the adhesive layer 22 can increase the strength of delamination resistance of the tab line 3, and prevent the delamination of the tab line 3. In the solar battery cell 2, the backside 2b of the substrate 11 is never exposed in the wiring-line region P due to the formation of the thin part S. Therefore, compared to the case where the backside 2b of the substrate 11 is exposed, the current collection efficiency can be ensured sufficiently.

Description

  The present invention relates to a solar battery cell and a solar battery module.

  The solar cell module is a device that directly converts light energy into electric energy, and thus attracts attention as clean energy, and the market is expected to expand rapidly in the future. Such a solar cell module generally has a structure in which a plurality of solar cells are connected in series according to a required voltage value.

  A plurality of linear finger electrodes are formed in parallel to each other on the surface (light-receiving surface) of the solar battery cell. Moreover, the back surface electrode is formed in the back surface of the photovoltaic cell over substantially the whole surface. Adjacent solar cells are connected to each other by tab wires. The tab line intersects the finger electrode of one solar battery cell and is connected to the back electrode of the other solar battery cell.

  Conventionally, solder showing good conductivity has been used for connecting the tab wires. However, in recent years, a technique has been developed in which an adhesive is used for connecting tab wires instead of solder. For example, in the solar cell module described in Patent Document 1, a back electrode made of an aluminum layer is used, and an opening is formed at a connection portion between the back electrode and the tab wire. As a result, the surface area of the back electrode can be reduced, and the pressure required to connect the tab wire and the back electrode with an adhesive can be reduced.

International Publication No. 2011/132682

  In the conventional configuration described above, the semiconductor substrate is exposed at the opening. For this reason, there exists a possibility that the power collection efficiency of a photovoltaic cell cannot fully be ensured in the part without an aluminum layer. On the other hand, when the aluminum layer and the tab line are bonded with an adhesive, cohesive failure occurs in the aluminum layer after the tab line is connected, and the tab line may be peeled off. Therefore, establishment of a technique capable of ensuring both current collection efficiency and prevention of tab wire peeling is required.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a solar battery cell and a solar battery module that can sufficiently secure current collection efficiency and can prevent tab wires from peeling off.

  In order to solve the above problems, a solar cell according to the present invention includes a substrate, a front surface electrode provided on the light receiving surface side of the substrate, and a back surface electrode provided on the back surface side of the substrate. And the back surface electrode is formed of an aluminum layer, and on the back surface side of the substrate, there is an arrangement region in which tab wires connecting the back surface electrode to the surface electrode of another solar battery cell are disposed via the adhesive layer. It is set, and at least a part of the arrangement region is characterized in that a thin portion having a thickness of the back electrode smaller than that of the back electrode other than the arrangement region is formed.

  In this solar cell, the back electrode is formed of an aluminum layer and is thin in at least a part of the arrangement region. For this reason, when connecting a tab wire to a back surface electrode via an adhesive layer, it becomes possible to fully penetrate the adhesive component of the adhesive layer into the thin aluminum layer. By strengthening the bond between the aluminum layer and the adhesive layer, it is possible to improve the peeling strength of the tab wire and prevent the peeling of the tab wire. In this solar cell, the back side of the substrate is not exposed in the wiring region due to the formation of the thin portion. Therefore, the current collection efficiency can be sufficiently ensured as compared with the case where the back surface side of the substrate is exposed.

  The aluminum layer is preferably formed by baking an electrode paste containing aluminum. The aluminum layer formed by firing the electrode paste has a porous interior. Therefore, the adhesive layer can be further sufficiently penetrated into the aluminum layer, and the peel strength of the tab wire can be improved more reliably.

  The aluminum layer is preferably porous. In this case, the adhesive layer can be more sufficiently penetrated into the aluminum layer. Therefore, the peel strength of the tab wire can be improved more reliably.

  Moreover, it is preferable that the adhesive bond layer formed with the conductive adhesive is arrange | positioned along the arrangement | positioning area | region. By using a solar battery cell with an adhesive layer, the convenience of connecting tab wires can be improved.

  The aluminum layer has a first layer having a predetermined thickness and a second layer having a thickness smaller than that of the first layer. In the thin portion, only the second layer is located on the back surface of the substrate. Preferably it is. Such a combination of the first layer and the second layer makes it possible to easily form the thin portion.

  Moreover, it is preferable that the thickness of a thin part is 5 micrometers-15 micrometers. In this range, the adhesive layer can be more sufficiently penetrated into the aluminum layer.

  Moreover, the solar cell module according to the present invention is characterized in that a plurality of the above-mentioned solar cells are arranged and the front surface electrode and the back surface electrode of the adjacent solar cells are connected by a tab wire.

  In this solar cell module, the back electrode of the solar cell is formed of an aluminum layer and is thin in at least a part of the arrangement region. For this reason, when connecting a tab wire to a back surface electrode via an adhesive layer, it becomes possible to fully penetrate the adhesive component of the adhesive layer into the thin aluminum layer. By strengthening the bond between the aluminum layer and the adhesive layer, it is possible to improve the peeling strength of the tab wire and prevent the peeling of the tab wire. Moreover, in this solar cell module, the back side of the substrate is not exposed in the wiring region due to the formation of the thin portion in the back electrode. Therefore, the current collection efficiency can be sufficiently ensured as compared with the case where the back surface side of the substrate is exposed.

  According to the solar battery cell and the solar battery module according to the present invention, it is possible to sufficiently secure the current collection efficiency and prevent peeling of the tab wire.

It is a typical perspective view showing an example of a solar cell module constituted using a photovoltaic cell concerning a 1st embodiment of the present invention. It is the typical top view which looked at the photovoltaic cell shown in FIG. 1 from the light-receiving surface side. It is the typical top view which looked at the photovoltaic cell shown in FIG. 1 from the back surface side. FIG. 4 is a schematic cross-sectional view taken along the line IV-IV in FIG. 3, showing a tab line disposed on the adhesive layer. It is typical sectional drawing which shows the modification of the back surface electrode in the photovoltaic cell which concerns on 1st Embodiment. It is the typical top view which looked at the photovoltaic cell concerning a 2nd embodiment from the back side. It is a VII-VII line typical sectional view of Drawing 6 shown in the state where a tab line has been arranged on an adhesive layer. It is a VIII-VIII typical sectional view of Drawing 6 shown in the state where a tab line has been arranged on an adhesive layer. It is typical sectional drawing which shows the modification of the back surface electrode in the photovoltaic cell which concerns on 2nd Embodiment. It is a graph which shows the result of the effect confirmation test of this invention.

Hereinafter, preferred embodiments of a solar battery cell and a solar battery module according to the present invention will be described in detail with reference to the drawings.
[First Embodiment]

  FIG. 1 is a schematic perspective view illustrating an example of a solar battery module configured using the solar battery cells according to the first embodiment of the present invention. As shown in the figure, the solar cell module 1 is configured by electrically connecting a plurality of solar cells 2 to each other by tab wires 3.

  One side of the solar battery cell 2 is a light receiving surface 2a on which a surface electrode is formed, and the other side of the solar battery cell 2 is a back surface 2b on which a back electrode is formed. Between adjacent solar cells 2, 2, the surface electrode on the light receiving surface 2 a side and the back electrode on the back surface 2 b side are connected by the tab wire 3, thereby the strings in which the solar cells 2 are connected in series. Is formed.

  The solar cell module 1 as a product includes, for example, a matrix in which a plurality of strings are arranged. The solar cell module 1 is laminated together with the front cover on the light receiving surface 2a side for protection and the back sheet on the back surface 2b side in a state where the matrix is sandwiched between sealing adhesive sheets. It is completed by attaching a metal frame.

  As the sealing adhesive, a translucent adhesive such as ethylene vinyl alcohol (EVA) resin is used. For the front cover, for example, a light-transmitting material such as glass is used, and for the back sheet, for example, a laminated body in which glass or aluminum foil is sandwiched between resin films is used.

  Next, the solar battery cell 2 will be described. FIG. 2 is a schematic plan view of the solar battery cell viewed from the light receiving surface side, and FIG. 3 is a schematic plan view of the solar battery cell viewed from the back surface side. As shown in FIGS. 2 and 3, the solar battery cell 2 has a substrate 11.

  The substrate 11 is formed in a substantially square shape by at least one of, for example, Si single crystal, polycrystal, and non-crystal. The four corners of the substrate 11 are chamfered in an arc shape. One surface of the substrate 11 corresponds to the light receiving surface 2 a of the solar battery cell 2, and the other surface of the substrate 11 corresponds to the back surface 2 b of the solar battery cell 2. The substrate 11 is, for example, an n-type semiconductor on the light receiving surface 2a side and a p-type semiconductor on the back surface 2b side.

  On the light receiving surface 2a side of the substrate 11, as shown in FIG. 2, a plurality of finger electrodes 12 are provided as surface electrodes. The finger electrodes 12 are formed on a substantially entire surface of the light receiving surface 2a of the substrate 11 in a direction substantially orthogonal to the extending direction of the strings of the solar cell module 1, and are arranged at a predetermined interval along the extending direction of the strings. Yes.

  The finger electrode 12 is formed by applying and heating a metal paste, for example. The thickness of the finger electrode 12 is, for example, 10 μm to 30 μm, and the width of the finger electrode 12 is, for example, 5 μm to 90 μm. Moreover, the space | interval between adjacent finger electrodes 12 and 12 is about 2 mm, for example.

  As a forming material of the finger electrode 12, it is formed by a glass paste containing silver, a silver paste in which various conductive particles are dispersed in an adhesive resin, a gold paste, a carbon paste, a nickel paste, an aluminum paste, and baking / vapor deposition. ITO etc. are mentioned. Among these, it is preferable to use a glass paste containing silver from the viewpoint of heat resistance, conductivity, stability, and cost.

  On the light receiving surface 2a side, the arrangement regions P and P of the pair of tab wires 3 are set in a direction substantially orthogonal to the finger electrodes 12. In this embodiment, the bus bar electrode for connecting the finger electrode 12 is not provided, and the tab wire 3 is directly connected to the finger electrode 12 via an adhesive layer 22 described later. An electrode may be provided. The arrangement region P is linearly set so as to straddle all the finger electrodes 12 on the light receiving surface 2a from the viewpoint of sufficiently securing the current collection efficiency of the solar cell module 1. Further, it is preferable that the spacing between the arrangement regions P and P be set to about twice the width of the tab line 3 in consideration of the alignment accuracy of the tab line 3.

  As shown in FIG. 3, a back electrode 14 is provided on the back surface 2 b side of the substrate 11. The back electrode 14 is formed over substantially the entire surface of the substrate 11 on the back surface 2b side. On the back surface 2b side, similarly to the light receiving surface 2a, the arrangement regions P and P of the pair of tab wires 3 are set, and the tab wire 3 is connected to the back electrode 14 through the adhesive layer 22. The arrangement area P is set linearly so as to correspond to the positions of the arrangement areas P and P on the light receiving surface 2a side.

  The back electrode 14 is formed of an aluminum layer 21 obtained, for example, by baking an aluminum paste. The inside of the aluminum layer 21 has a porous shape due to voids formed when the aluminum paste is fired. The porosity of the aluminum layer 21 before connection of the tab wire 3 is preferably 10% or more, for example. In addition, the surface roughness of the aluminum layer 21 is preferably 2 μm or less, more preferably 1 μm or less, in terms of centerline average roughness. The surface roughness of the aluminum layer 21 is preferably, for example, 10 μm or less in terms of 10-point average roughness. These surface roughnesses are defined by JIS B 0601 (1994) and JIS B 0031 (1994).

  More specifically, the aluminum layer 21 includes a first layer 21A having a predetermined thickness and a second layer 21B having a thickness smaller than that of the first layer 21A. The thickness of the first layer 21A is, for example, about 20 μm to 30 μm. The first layer 21A is formed in a region excluding the wiring region P. On the other hand, the thickness of the second layer 21B is, for example, about 5 μm to 15 μm. The second layer 21B is formed corresponding to the wiring region P, and is exposed between the first layers 21A and 21A in the wiring region P.

  With such a configuration of the first layer 21A and the second layer 21B, a thin-walled portion S smaller than the thickness of the portion other than the placement region P is formed on the back electrode 14 over substantially the entire length of the placement region P. Yes. As described above, the width of the wiring region P is about twice the width of the tab line 3, and the width of the second layer 21B exposed between the first layers 21A and 21A is also the tab line 3. It is about twice the width of. Both end portions in the width direction of the second layer 21B may project outward from the wiring region P, and the first layer 21A may overlap the projecting portion (see FIG. 4).

  For example, a conductive adhesive is used to connect the tab wire 3 to the finger electrode 12 and the back electrode 14. Examples of the conductive adhesive include 25 parts by mass of a film-forming resin, 20 parts by mass of a thermosetting resin, 55 parts by mass of a curing agent for the thermosetting resin, 10 parts by mass of silicone particles, and 10 parts by mass of conductive particles. Parts contained respectively.

  As the film-forming resin, for example, a thermoplastic polymer such as a phenoxy resin, a polyester resin, and a polyamide resin is used from the viewpoint that good film formation can be performed. Among these resins, it is preferable to use a phenoxy resin. The weight average molecular weight of the thermoplastic polymer is preferably 10,000 to 10,000,000 in consideration of the fluidity of the adhesive layer 22.

  Examples of the thermosetting resin include epoxy resins, polyimide resins, unsaturated polyester resins, polyurethane resins, bismaleimide resins, triazine-bismaleimide resins, and phenol resins. Among these resins, it is preferable to use an epoxy resin in consideration of heat resistance.

  The curing agent for a thermosetting resin refers to a material that accelerates the curing of the thermosetting resin when heated together with the thermosetting resin. Examples of such curing agents include imidazole curing agents, hydrazide curing agents, amine curing agents, phenol curing agents, acid anhydride curing agents, boron trifluoride-amine complexes, sulfonium salts, iodonium salts, and polyamines. Salts, amine imides, and dicyandiamide are used. When an epoxy resin is used as the thermosetting resin, it is preferable to use, for example, an imidazole curing agent, a hydrazide curing agent, a boron trifluoride amine complex, a sulfonium salt, an amine imide, a polyamine salt, and dicyandiamide. .

Examples of the silicone particles include silicone rubber particles, silicone resin particles, and silicone composite particles. The silicone rubber particles are, for example, silicone rubber particles having a structure in which linear dimethylpolysiloxane is crosslinked. Silicone resin particles are, for example, particles of a polyorganosilsesquioxane cured product having a structure in which siloxane bonds are crosslinked in a three-dimensional network represented by (RSiO _3/2 ) n.

  Examples of the conductive particles include gold particles, silver particles, copper particles, nickel particles, gold plated nickel particles, gold / nickel plated plastic particles, copper plated particles, and nickel plated particles. From the viewpoint of ensuring conductivity, the average particle size of the conductive particles is preferably 1 μm to 20 μm, and more preferably 1 μm to 5 μm.

  Further, the conductive adhesive may contain a coupling agent for improving the adhesion and wettability with the adherend. Examples of the coupling agent include silane coupling agents and titanate coupling agents.

  Subsequently, the connection between the back electrode 14 and the tab wire 3 will be described. 4 is a schematic cross-sectional view taken along the line IV-IV in FIG. 3 showing a state in which the tab line is disposed on the adhesive layer. As shown in the figure, when connecting the tab wire 3, an adhesive film formed using the conductive adhesive is pasted along the arrangement region P, and an adhesive layer is formed on the second layer 21B. 22 is formed. The adhesive layer 22 may be formed on the second layer 21B in advance as a configuration on the solar battery cell 2 side. Next, the tab wire 3 is temporarily fixed on the adhesive layer 22. As the tab wire 3, for example, a copper ribbon having a width of about 1 mm to 2 mm in which the surface of the copper ribbon is coated with solder is used. The tab wire 3 is not particularly limited, but may be one that does not cover the surface with solder. Moreover, it is preferable that the opposing surface which opposes the adhesive bond layer 22, and the opposite surface become flat surfaces. The flat surface height variation (difference in unevenness) is, for example, preferably 5 μm, and more preferably 2 μm or less, within a range of 500 μm in the width direction of the tab wire 3.

  After the tab wire 3 is temporarily fixed, the tab wire 3 and the back electrode 14 are thermocompression bonded using, for example, a thermocompression bonding machine. The temperature at the time of thermocompression bonding is, for example, about 80 ° C to 320 ° C. The pressure at the time of thermocompression bonding is, for example, 1.0 MPa or more, preferably 3.0 MPa or more. The pressure application time is, for example, about 1 second to 30 seconds. By thermocompression bonding, the adhesive component of the adhesive layer 22 enters the aluminum layer 21 and the tab wire 3 is fixed to the back electrode 14.

  In the solar battery cell 2, as described above, the back electrode 14 is formed by the porous aluminum layer 21. The aluminum layer 21 is composed of a first layer 21A and a second layer 21B having different thicknesses. In the placement region P, a thin portion S smaller than the thickness of a portion other than the placement region P is formed. . For this reason, when the tab wire 3 is connected to the back electrode 14 by thermocompression bonding, the adhesive component of the adhesive layer 22 can sufficiently penetrate into the thin second layer 21B. When the adhesive component sufficiently penetrates into the second layer 21B, the bonding between the aluminum layer 21 and the adhesive layer 22 is strengthened, and the peel strength of the tab wire 3 can be improved. Separation can be prevented.

  Further, in the solar battery cell 2, the back surface 2 b side of the substrate 11 is not exposed in the wiring region P due to the formation of the thin portion S, and is covered with the second layer 21 </ b> B of the aluminum layer 21. Therefore, compared with the case where the back surface 2b side of the substrate 11 is exposed, aluminum diffuses into the substrate 11 and a P-type semiconductor layer is sufficiently formed on the back surface 2b of the substrate 11, so that sufficient current collection efficiency can be secured. .

In the example shown in FIG. 4, the second layer 21B is formed corresponding to the wiring region P. However, as shown in FIG. 21B may be formed, and the first layer 21A may be formed so as to overlap the second layer 21B in a portion other than the wiring region P. Even in such an aspect, since the thin portion S smaller than the thickness of the portion other than the placement region P is formed in the placement region P, the same effect as the above embodiment can be obtained.
[Second Embodiment]

  FIG. 6 is a schematic plan view of the solar battery cell according to the second embodiment viewed from the back side. As shown in the figure, the photovoltaic cell 32 according to the second embodiment is different from the first embodiment in the pattern of the thin portion S. More specifically, in the solar battery 32, the second layer 21B and the first layer 21A of the aluminum layer 21 are formed over substantially the entire surface on the back surface 2b side in order from the back surface 2b side of the substrate 11. And in the arrangement | positioning area | region P, the thin layer S is formed because the 1st layer 21A opens in a rectangular pattern at equal intervals, and the 2nd layer 21B is exposed.

  The length in the longitudinal direction of the arrangement region P in the opening pattern is set in a range of about 1 mm to 30 mm, for example. The length in the width direction of the arrangement region P in the opening pattern is set to, for example, about twice the width of the tab line 3 as in the first embodiment. The interval between the opening patterns is, for example, about 0.2 to 0.3 times the length of the arrangement region P in the opening pattern in the longitudinal direction. In the position where the thin portion S is not formed, the tab wire 3 is disposed on the first layer 21A and the second layer 21B via the adhesive layer 22, as shown in FIG. It is fixed to the first layer 21A and the second layer 21B via the layer 22. On the other hand, at the position where the thin portion S is formed, the tab wire 3 is disposed on the second layer 21B via the adhesive layer 22 and then the adhesive layer 22 as shown in FIG. To be fixed to the second layer 21B.

  Also in such a solar battery cell 32, the aluminum layer 21 is constituted by the first layer 21A and the second layer 21B having different thicknesses, and the arrangement region P is smaller than the thickness of the portion other than the arrangement region P. A thin portion S is formed. For this reason, when the tab wire 3 is connected to the back electrode 14 by thermocompression bonding, the adhesive component of the adhesive layer 22 can sufficiently penetrate into the thin second layer 21B. When the adhesive component sufficiently penetrates into the second layer 21B, the bonding between the aluminum layer 21 and the adhesive layer 22 is strengthened, and the peel strength of the tab wire 3 can be improved. Separation can be prevented.

  Also in the solar battery 32, the formation of the thin portion S prevents the back surface 2 b side of the substrate 11 from being exposed in the wiring region P and is covered with the second layer 21 </ b> B of the aluminum layer 21. Therefore, compared with the case where the back surface 2b side of the substrate 11 is exposed, aluminum diffuses into the substrate 11 and a P-type semiconductor layer is sufficiently formed on the back surface 2b of the substrate 11, so that sufficient current collection efficiency can be secured. .

As shown in FIG. 9, the first layer 21A having the opening pattern formed on the back surface 2b side of the substrate 11, and the substrate 11 exposed from the opening patterns of the first layer 21A and the first layer 21A. The second layer 21B may be formed so as to cover the back surface 2b side. Even in such an aspect, since the thin portion S smaller than the thickness of the portion other than the placement region P is formed in the placement region P, the same effect as the above embodiment can be obtained. The shape of the opening pattern is not limited to a rectangle, and may be another shape such as a polygon or a circle.
[Effectiveness confirmation test]

  The effect confirmation test of the present invention will be described. In this test, the peel strength of the tab wire having a width of 1.5 mm fixed to the aluminum layer via the adhesive layer (the tensile force per tab wire) while changing the thickness of the aluminum layer in the tab wire arrangement region. ). For measurement of peel strength, Tensilon (STA-1150) manufactured by Orientec Co., Ltd. is used, the tab wire is pulled up at a speed of 50 mm / min in the normal direction of the solar cell, and the force required for pulling is recorded and measured. It was.

  In this test, first, a 125 mm square blue cell with textured and SiN film formed was prepared. Next, an aluminum paste was screen-printed on the Si surface on the back surface of the substrate to form a precursor pattern of the second layer, and dried at 150 ° C. for 1 minute. Further, an aluminum paste was screen printed on the Si surface on the back surface of the substrate to form a precursor pattern of the first layer, and dried at 150 ° C. for 1 minute. After forming the first layer and the second layer, a glass paste containing silver is screen-printed on the Si surface of the substrate to form a finger electrode precursor pattern, and dried at 150 ° C. for 1 minute. It was. Next, the solar cell on which the precursor was printed was continuously heated at 350 ° C., 800 ° C., and 550 ° C. for 30 seconds to form a desired electrode pattern.

  In addition, the thickness adjustment of the aluminum layer for forming a 2nd layer was performed by adding and diluting commercially available alpha-terpineol (organic solvent) to an aluminum paste. To form an aluminum layer having a thickness of 10 μm, 50 g of α-terpineol was added to 100 g of aluminum paste and stirred. To form an aluminum layer having a thickness of 23 μm, 10 g of α-terpineol was added to 100 g of aluminum paste and stirred. In addition, α-Terpineol was not added to form an aluminum layer having a thickness of 35 μm.

  After the formation of the electrode pattern, the conductive film was temporarily fixed in four arrangement regions under the conditions of a temperature of 90 ° C., a pressure of 1 Mpa, and a time of 1 second. As the conductive adhesive film, a conductive film (CF-205, width 1.2 mm) manufactured by Hitachi Chemical Co., Ltd. composed of two layers of a separator and a conductive adhesive layer was used. Next, the separator of the conductive film was peeled off to form an adhesive layer made of a conductive adhesive. Subsequently, a tab wire was laminated on the adhesive layer at 70 ° C. to obtain a solar battery cell. Tab wires (SSA-TPS-0.2 × 1.5 (20)) manufactured by Hitachi Cable, Ltd. were used for the tab wires. Further, TAB Stringer ATS-200 manufactured by Shibaura Mechatronics Co., Ltd. was used for connection of the tab wires. The tab wire connection conditions were a temperature of 190 ° C., a pressure of 2 MPa, and a time of 5 seconds.

  FIG. 10 is a graph showing the results of the effect confirmation test of the present invention. As shown in the figure, when the thickness of the aluminum layer was 35 μm, the peel strength of the tab wire was 0.23 N / TAB. On the other hand, when the aluminum layer thickness is 23 μm, the tab wire peel strength is 0.95 N / TAB, and when the aluminum layer thickness is 10 μm, the tab wire peel strength is 2.32 N / TAB. TAB. From this result, it was confirmed that the peeling strength of the tab wire can be improved by forming the thin portion of the aluminum layer in the arrangement region.

  DESCRIPTION OF SYMBOLS 1 ... Solar cell module, 2, 32 ... Solar cell, 2a ... Light-receiving surface, 2b ... Back surface, 3 ... Tab wire, 11 ... Substrate, 12 ... Finger electrode (front surface electrode), 14 ... Back electrode, 21 ... Aluminum layer 21A ... first layer, 21B ... second layer, 22 ... adhesive layer, P ... arrangement region, S ... thin portion.

Claims (7)

A solar cell comprising: a substrate; a surface electrode provided on a light receiving surface side of the substrate; and a back electrode provided on a back surface side of the substrate,
The back electrode is formed of an aluminum layer,
On the back side of the substrate, an arrangement region is set in which tab wires for connecting the back electrode to the surface electrodes of other solar cells are arranged via an adhesive layer,
In at least a part of the arrangement region, a thin-walled portion in which the thickness of the back electrode is smaller than the thickness of the back electrode other than the arrangement region is formed.   The solar cell according to claim 1, wherein the aluminum layer is formed by firing an electrode paste containing aluminum.   The solar cell according to claim 1, wherein the aluminum layer has a porous shape.   The photovoltaic cell according to any one of claims 1 to 3, wherein the adhesive layer formed of a conductive adhesive is arranged along the arrangement region. The aluminum layer has a first layer having a predetermined thickness and a second layer having a thickness smaller than that of the first layer,
5. The solar cell according to claim 1, wherein in the thin portion, only the second layer is located on the back surface of the substrate.   The thickness of the said thin part is 5 micrometers-15 micrometers, The solar cell as described in any one of Claims 1-5 characterized by the above-mentioned. A plurality of solar cells according to any one of claims 1 to 6 are arranged,
A solar cell module, wherein the front surface electrode and the back surface electrode of adjacent solar cells are connected by the tab wire.

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