HK1185720A - Solar cell module, and method of manufacturing solar cell module - Google Patents

Description

Solar cell module and method for manufacturing solar cell module

Technical Field

The present invention relates to a solar cell module including a plurality of solar cell units, each of which is electrically connected to a connection electrode via a TAB Line (TAB Line), and a method of manufacturing the solar cell module.

This application is a patent application that claims priority based on japanese patent application No. 2010-274844, which was filed in japan on 12, 9, 2010, and is incorporated herein by reference.

Background

In general, a solar cell is used as a solar cell module that realizes an output of 100W or more by connecting a plurality of solar cells in series.

In a silicon-type solar cell module, a plurality of adjacent solar cells are connected to each other by a TAB line made of a conductive material such as a solder-coated strip-shaped copper foil as an interconnector (interconnector). Each solar cell is connected in series by connecting one end of the TAB wire to the front surface electrode of one solar cell and the other end to the back surface electrode of the adjacent solar cell.

In recent years, as a TAB line, a TAB line having a concave-convex portion formed on one surface has been proposed. For example, as shown in fig. 11, the TAB line 100 is formed in an elongated shape, and has a surface 101a on the light receiving side formed with an uneven portion 102. As shown in fig. 12, the uneven portion 102 is formed by a plurality of convex portions 102a and concave portions 102b that are continuous in the longitudinal direction of the TAB line 100 and are alternately provided in the width direction.

Further, in the TAB line 100, the back surface 101b is connected to the front surface electrode 103a of the solar cell 103 via the conductive adhesive film 104. Thus, since the concave-convex portion 102 of the solar cell 103 faces the light receiving surface side, the incident light is scattered by the concave-convex portion 102. The scattered light is reflected by the surface of the cover glass and is incident again on the light receiving surface. This results in the finding that the light blocking effect of the solar cell module including the TAB line 100 improves the power generation efficiency, and as a result, the power generation efficiency can be improved.

Patent document 1 describes a structure of a solar cell module including a plurality of solar cells arranged in series by a TAB line having a concave-convex portion formed on the surface on the light receiving side.

On the other hand, patent document 2 describes a solar cell module including a TAB line having a concave-convex portion formed on a surface on a side facing a connection electrode. The TAB line disclosed in patent document 2 has a convex portion in contact with a connection electrode, and a conductive resin material is filled between the TAB line and the connection electrode. Further, by increasing the height of the uneven portion, the connection reliability (adhesive strength) of the TAB line can be improved.

(Prior art document)

Patent document

Patent document 1: japanese patent application laid-open No. 2010-16300;

patent document 2: japanese patent laid-open No. 2008-147567.

Disclosure of Invention

(problems to be solved by the invention)

In this way, in the solar cell including the TAB line having the uneven portion formed on one surface and the flat surface on the opposite side, a difference occurs in the pressure applied to the front surface and the back surface when the TAB line is bonded. For this reason, the solar cell becomes to generate stress deformation on the front surface electrode side and the back surface electrode side. When the solar battery unit generates stress deformation, the hidden danger of cracking and bending exists.

In the crystalline silicon solar cell, it is an object to economically and abundantly supply silicon as a raw material, and in recent years, silicon wafers are cut out from a crystalline silicon ingot in an extremely thin shape (for example, 200 μm to 150 μm) and are used in mass production. In such a thin solar cell, cracking and bending due to stress deformation are more likely to occur.

In addition, in the TAB wire, a planar surface facing each of the front surface electrode and the back surface electrode may not be connected to each of the front surface electrode and the back surface electrode with sufficient adhesive strength.

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide a solar cell module capable of obtaining sufficient connection reliability with a TAB line while maintaining a good shape state of a solar cell, and a method for manufacturing such a solar cell module.

(means for solving the problems)

In order to solve the above problems, the present invention relates to a solar cell module in which a front surface electrode of a predetermined solar cell among a plurality of solar cells and a rear surface electrode of another solar cell adjacent to the predetermined solar cell are connected by a TAB line, wherein the TAB line has a plurality of convex and concave portions formed on both the front and back surfaces, the convex and concave portions being continuous in the longitudinal direction and alternately arranged in the width direction, one end of the front electrode is connected to the front surface electrode, and the other end of the front electrode is connected to the back surface electrode via an adhesive resin material, and the concave-convex angle formed by a line segment connecting the vertex of the convex portion and the vertex of the concave portion adjacent to the convex portion and a line segment connecting the vertices of the concave portions adjacent to both sides of the convex portion is 10 ° to 50 °.

In order to solve the above problem, the present invention relates to a method for manufacturing a solar cell module in which a front surface electrode of a predetermined solar cell among a plurality of solar cells and a rear surface electrode of another solar cell adjacent to the predetermined solar cell are connected by a TAB line, the method including: and a pressure bonding step of pressure bonding a TAB line via an adhesive resin material to each of a front surface electrode and a back surface electrode of the solar cell, wherein the TAB line has a plurality of projections and recesses alternately arranged in a width direction and formed on both surfaces of the front surface and the back surface, the projections and recesses being continuous in a longitudinal direction, and a projection and recess angle formed by a line segment connecting a vertex of the projection and a vertex of the recess adjacent to the projection and a line segment connecting vertices of the recesses adjacent to both sides of the projection is 10 DEG to 50 DEG, and in the pressure bonding step, one end of the TAB line is connected to the front surface electrode, and the other end of the TAB line is connected to the back surface electrode via the adhesive resin material.

According to the present invention, it is possible to prevent deformation of the solar cell unit, maintain a good shape state, and obtain sufficient connection reliability with the TAB line.

Drawings

Fig. 1 is an exploded perspective view showing the structure of a solar cell module;

fig. 2 is a longitudinal sectional view of a battery strip of a solar cell unit;

fig. 3 is a perspective view showing a solar cell connected by a TAB line;

fig. 4 is a cross-sectional view of a solar cell unit;

FIG. 5 is a cross-sectional view in the width direction of the TAB line;

fig. 6 is a cross-sectional view in the width direction of the conductive adhesive film;

FIG. 7 is a schematic view showing an example of the shape of a conductive adhesive film;

FIG. 8 is a schematic view for explaining a temporary bonding process of a TAB wire;

FIG. 9 is a schematic view for explaining a main pressure bonding process of the TAB wire;

fig. 10 is a cross-sectional view of a solar cell unit;

fig. 11 is a perspective view showing a solar cell connected by a conventional TAB line;

fig. 12 is a cross-sectional view in the width direction of a conventional TAB line.

Detailed Description

Hereinafter, embodiments of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail with reference to the drawings.

[ solar cell Module ]

Fig. 1 is an exploded perspective view showing the structure of a solar cell module 1 having a TAB line applied to the present invention. The solar cell module 1 includes a cell bar 4 in which a plurality of solar cells 2 are connected in series by TAB lines 3 constituting interconnectors (interconnectors), and includes a matrix 5 in which a plurality of cell bars 4 are arranged.

The solar cell module 1 is formed by laminating a front cover 7 provided on the light receiving surface side and a back sheet 8 provided on the back side with a sheet 6 of sealing adhesive interposed therebetween, and attaching a metal frame 9 of aluminum or the like around the front cover and the back sheet.

As the sealing adhesive for the sheet 6, for example, a light-transmitting sealing material such as Ethylene Vinyl Acetate Resin (EVA) is used. As the front cover 7, for example, a light-transmitting material such as glass or light-transmitting plastic is used. As the back sheet 8, a laminate in which glass or aluminum foil is sandwiched by resin films, or the like is used.

Fig. 2 is a longitudinal sectional view of a battery string 4 in which solar battery cells 2 are connected in series. Each solar cell 2 includes a photoelectric conversion element 10. As the photoelectric conversion element 10, various photoelectric conversion elements 10 such as a crystalline silicon solar cell module using a single-crystal silicon photoelectric conversion element, a polycrystalline silicon photoelectric conversion element, or the like, a thin-film silicon solar cell using a photoelectric conversion element in which a unit made of amorphous silicon and a unit made of microcrystalline silicon or amorphous silicon germanium are stacked, or the like can be used.

On the light-receiving surface of the photoelectric conversion element 10, a bus bar electrode 11 and a finger electrode 12 as a collector electrode formed in a direction substantially orthogonal to the bus bar electrode 11 are provided as surface electrodes. A back surface electrode 13 made of aluminum, silver, or the like is provided on the surface opposite to the light receiving surface of the photoelectric conversion element 10.

Each solar cell 2 is electrically connected to a bus bar electrode 11 of a predetermined solar cell 2 and a back surface electrode 13 of an adjacent solar cell 2 by a TAB line 3, thereby constituting a battery string 4.

Specifically, one surface 30b of the TAB line 3 is connected to the bus bar electrode 11 of the solar cell 2 via the conductive adhesive film 15a at one end 3a of the TAB line 3. The other surface 30a of the TAB line 3 at the other end 3b of the TAB line 3 is connected to the rear surface electrode 13 of the solar cell 2 adjacent thereto via the conductive adhesive film 15 b.

The finger electrodes 12 are formed by applying Ag paste and heating. The finger electrodes 12 are formed over substantially the entire light-receiving surface of the solar cell 2. The finger electrodes 12 are formed, for example, as lines having a width of about 100 μm at predetermined intervals of, for example, 2 mm.

The bus bar electrodes 11 are formed by the same method as the finger electrodes 12. The bus bar electrodes 11 are formed linearly with a width of 1mm, for example, so as to intersect the bus bar electrodes 11 on the surface of the photoelectric conversion element 10 constituting the light receiving surface of the solar cell 2, in order to reduce the area for blocking incident light and to suppress shadow loss (shadow loss).

The number of the bus bar electrodes 11 is appropriately set in consideration of the size and the impedance of the solar battery cell 2. On the bus bar electrode 11, a conductive adhesive film 15a is provided, and an end portion 3a of the TAB line 3 is provided thereon. Thereby, the bus bar electrode 11 is connected to the surface 30b of the end 3a of the TAB line 3 via the conductive adhesive film 15 a.

The back electrode 13 is formed on the back surface of the photoelectric conversion element 10 by an electrode made of aluminum, silver, or the like, for example, screen printing, sputtering, or the like. The back electrode 13 is connected to the front surface 30a of the end 3b of the TAB line 3 via a conductive adhesive film 15 b.

In this way, the solar cell 2 included in the solar cell module 1 is mechanically connected to the TAB line 3 on both the front surface and the back surface, and is electrically connected to the adjacent solar cell 2 via the TAB line 3.

[ TAB line ]

As shown in fig. 3, the TAB wire 3 is formed in a long shape using, for example, a strip-shaped copper foil 50 to 300 μm thick, and is plated with gold, silver, tin, solder, or the like as necessary. In the TAB line 3, the uneven portions 21 are formed in the longitudinal direction on the first surface 30a and the second surface 30b, respectively. In the TAB wire 3, one end portion 3a is fixedly connected to the bus bar electrode 11 of the solar cell 2, and the other end portion 3b is fixedly connected to the back surface electrode 13 of the adjacent solar cell.

Specifically, as shown in fig. 4, the TAB line 3 has a plurality of projections 31 and recesses 32 that are continuous in the longitudinal direction of the TAB line 3 and are alternately provided in the width direction on both the front and back surfaces, i.e., on both the front and back surfaces 30a and 30b, thereby forming the uneven portions 21. The uneven portion 21 is formed by extrusion molding or the like of the strip-shaped copper foil after the plating treatment.

In addition, the surface treatment may be performed by a known method in the concave-convex portion. The convex portion is not limited to the portion constituting an acute angle, and may be a somewhat dotted rounded angle within a range in which the concave-convex angle α can be measured.

The TAB line 3 has a center line m in a cross section in the width direction₁The boundary is a symmetric shape of the front surface and the back surface. Thus, the TAB lines 3 having the front and rear surfaces of symmetrical shapes are connected to the solar cells 2 of the bus bar electrodes 11 and the rear surface electrodes 13, and the occurrence of warpage due to stress deformation generated when the TAB lines 3 are connected can be prevented.

That is, since the TAB line 3 has a symmetrical shape in front and back surfaces, when the TAB line is connected to the bus bar electrode 11 and the back surface electrode 13 by heating and pressing, which will be described later, uniform stress is applied to the front surface side and the back surface side of the solar cell 2. Therefore, the solar battery cell 2 can minimize the difference in stress applied to the front surface and the back surface on the light receiving surface side. Thus, the solar cell 2 can minimize the stress strain caused by the shape of the TAB line 3 on both the front and back surfaces, and therefore, it is possible to prevent the occurrence of cracking or bending.

In the predetermined solar cell 2, the uneven portion 21 on the surface 30b of the end portion 3a of the TAB line 3 is connected to the bus bar electrode 11 of the solar cell 2 via the conductive adhesive film 15a, as shown in fig. 5. As will be described later, the conductive adhesive film 15a flows by heating the binder resin, and enters the concave portion 32 of the concave-convex portion 21. As a result, as will be described later, the TAB line 3 having a predetermined concave-convex angle can improve the connection strength with each of the bus bar electrode 11 and the back surface electrode 13 of the solar cell 2.

In the predetermined solar cell 2, on the light receiving surface side, the incident light entering the uneven portion 21 on the surface 30a of the end portion 3a of the TAB line 3 is scattered by the uneven portion 21, and the scattered light is reflected by the surface cover 7 made of glass or the like and enters the light receiving surface. This improves the power generation efficiency of the solar battery cell 2.

The uneven portions 21 on the surface 30a of the end portion 3b of the TAB wire 3 are connected to the rear surface electrodes 13 of the solar cells 2 adjacent to the predetermined solar cell 2 via the conductive adhesive film 15 b. In this connection, the conductive adhesive film 15b enters the concave portion 32 of the concave-convex portion 21 by the flow caused by the heating of the binder resin, and thereby the connection reliability (adhesive strength) with the rear surface electrode 13 can be improved.

In this way, the TAB line 3 included in the solar cell module 1 has the uneven portions 21 having a predetermined uneven angle formed on both the front and rear surfaces 30a and 30 b. Thus, in the solar cell module 1, the TAB line 3 and the bus bar electrode 11, and the TAB line 3 and the back surface electrode 13 are mechanically connected with high bonding strength in each of the predetermined solar cells 2, and the bus bar electrode 11 of the predetermined solar cell 2 and the back surface electrode 13 of the solar cell 2 adjacent to the predetermined solar cell 2 are electrically connected with high connection reliability.

Next, the concave-convex angle of the concave-convex portion 21 will be described. As shown in FIG. 4, the peak b of the convex portion 31 is formed on the cross section of the TAB line 3 in the width direction₁And a peak (lowest point) a of the concave portion 32 adjacent to both sides of the convex portion 31₁Line segment a formed by connection₁b₁And the apex a of the concave portion 32 to be adjacent to the convex portion 31₁Line segment a formed by inter-connection₁a₁The angle formed is defined as the concave-convex angle α of the TAB line 3. The TAB line 3 is formed so as to cross the center line m₁Becomes a symmetrical shape of the front and back as a boundary. Therefore, the same value of the concave-convex angle α can be obtained from the convex portion 31 and the concave portion 32 on the other surface 30 b.

The concave-convex angle α is preferably 10 ° to 50 °, and particularly preferably 20 ° to 40 °. By making the concave-convex angle α 10 ° or more and 50 ° or less, incident light can be scattered and reflected by the surface cover 7, and the solar cell module 1 can exhibit a light blocking effect, thereby improving power generation efficiency.

Further, by making the concave-convex angle α 10 ° or more, a sufficient amount of the conductive adhesive film 15 (conductive adhesive films 15a and 15 b) enters the concave portion 32 of the concave-convex portion 21 by the flow caused by heating, and thereby, the connection reliability between the TAB line 3 and the bus bar electrode 11, and between the TAB line 3 and the back surface electrode 13 can be improved.

As shown in fig. 5, the TAB wire 3 is bonded to the conductive adhesive film 15a at the uneven portions 21 of the surface 30b with high adhesive strength, and is connected to the bus bar electrodes 11 of the solar battery cells 2. When incident light is incident on the concave-convex portion 21 of the surface 30a, it is scattered by the concave-convex portion 21. The scattered light is reflected by the surface cover 7, which is a protective glass surface, and enters the photoelectric conversion element 10 again.

As a result of the solar cell module 1 having the light blocking effect and the improved power generation efficiency, the power generation efficiency can be improved, and the reliability of connection between the TAB line 3 and the bus bar electrode 11 can be improved by inserting a sufficient amount of the conductive adhesive film 15a into the concave portion 32 of the uneven portion 21.

[ conductive adhesive film ]

As shown in fig. 6, for example, the conductive adhesive film 15 is formed by containing conductive particles 24 in a thermosetting adhesive resin layer 23 at a high density. In addition, from the viewpoint of extrudability, the conductive adhesive film 15 preferably has a minimum melt viscosity of 100 to 100000Pa seeds of the binder resin.

When the minimum melt viscosity is too low, the conductive adhesive film 15 is likely to cause poor connection due to the flow of the resin during the contact from low pressure to main curing, and to overflow to the cell light-receiving surface, which causes a decrease in light acceptance. Even if the minimum melt viscosity is too high, defects are likely to occur when the films are bonded, and the connection reliability may be adversely affected. The lowest melt viscosity can be measured by loading a sample in a predetermined amount of a rotary viscometer and raising the temperature at a predetermined rate.

The conductive particles 24 used in the conductive adhesive film 15 are not particularly limited, and examples thereof include metal particles such as nickel, gold, and copper, particles obtained by plating resin particles with gold, and particles obtained by insulating and covering the outermost layer of particles obtained by plating resin particles with gold. Further, by containing flat flake-like metal particles as the conductive particles 24, the number of the conductive particles 24 overlapping each other can be increased, and good conduction reliability can be secured.

The conductive adhesive film 15 preferably has a viscosity of 10 to 10000kPa for seeds and seeds, and more preferably 10 to 5000kPa for seeds and seeds, at around room temperature. When the conductive adhesive film 15 has a viscosity in the range of 10 to 10000kPa or more, for example, in the case where the conductive adhesive film 15 is formed into a magnetic tape-shaped reel body as described later, the so-called blooming can be prevented, and a predetermined viscous force can be maintained.

The composition of the adhesive resin layer of the conductive adhesive film 15 is not particularly limited as long as the above-described characteristics are not impaired, but more preferably contains a film-forming resin, a liquid epoxy resin, a latent curing agent, and a silane coupling agent.

The film-forming resin corresponds to a high molecular weight resin having an average molecular weight of 10000 or more, and preferably has an average molecular weight of approximately 10000 to 80000 from the viewpoint of thin film formability. As the film-forming resin, various resins such as an epoxy resin, a denatured epoxy resin, a urethane resin, and a phenoxy resin can be used, and among them, the phenoxy resin is more preferably used from the viewpoint of the film-forming state, connection reliability, and the like.

The liquid epoxy resin is not particularly limited as long as it has fluidity at room temperature, and all of the commercially available epoxy resins can be used. Specific examples of such epoxy resins include naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, bisphenol type epoxy resins, stilbene type epoxy resins, triphenylmethane type epoxy resins, aralkyl phenol type epoxy resins, naphthol type epoxy resins, dicyclopentadiene type epoxy resins, and triphenylmethane type epoxy resins. These can be used alone, or in combination of 2 or more. In addition, the resin composition may be used in combination with other organic resins such as acrylic resins as appropriate.

As the latent curing agent, various curing agents such as a heat curing type and a UV curing type can be used. The latent curing agent is usually not reacted and is activated by some trigger to start the reaction. The trigger may be selected and used according to the application, such as heat, light, and pressure. When a liquid epoxy resin is used, a latent curing agent composed of an imidazole, an amine, a sulfonium salt, an onium salt (onium salt), or the like can be used.

As the silane coupling agent, epoxy, amino, mercapto, sulfide, and ureide compounds can be used. Among these, an epoxy silane coupling agent is preferably used in the present embodiment. This improves the adhesion at the interface between the organic material and the inorganic material.

In addition, as another additive composition, it is preferable to contain an inorganic filler. By containing the inorganic filler, the fluidity of the resin layer at the time of pressure bonding can be adjusted, and the particle capture rate can be improved. As the inorganic filler, silica, talc, titanium oxide, calcium carbonate, magnesium oxide, and the like can be used, and the kind of the inorganic filler is not particularly limited.

Fig. 7 is a schematic diagram showing an example of the shape of the conductive adhesive film 15. The conductive adhesive film 15 is formed into a magnetic tape shape by providing a release substrate 25 on one surface thereof as a film laminate. The magnetic tape-shaped conductive adhesive film 15 is wound and laminated on the reel 26 so that the release substrate 25 is positioned on the outer peripheral side, thereby forming a reel body 27.

The release substrate 25 is not particularly limited, and PET (polyethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methyl-pentene-1: polymethylpentene), PTFE (Polytetrafluoroethylene), and the like can be used. The conductive adhesive film 15 may have a transparent cover film on the surface opposite to the surface on which the release substrate 25 is provided.

In this case, the TAB line 3 may be used as a cover film to be attached to the adhesive resin layer. The TAB wire 3 and the conductive adhesive film 15 are laminated and integrated in advance, and in actual use, the conductive adhesive film 15 is bonded to the bus bar electrode 11 and the back surface electrode 13 by peeling the peeling base 25, whereby the TAB wire 3 can be connected to the bus bar electrode 11 and the back surface electrode 13. The conductive adhesive film 15 is not limited to a reel shape, and may be, for example, a strip shape.

When the conductive adhesive film 15 is provided as the reel body 27, the viscosity of the conductive adhesive film 15 is set in the range of 10 to 10000kPa, seeds, etc., whereby the conductive adhesive film 15 can be prevented from being deformed and a predetermined size can be maintained. Further, as in the case of stacking 2 or more conductive adhesive films 15 in a long strip shape, deformation can be prevented and a predetermined size can be maintained.

For example, the conductive adhesive film 15 can be produced as follows. First, the conductive particles 24, the film-forming resin, the liquid epoxy resin, the latent curing agent, and the silane coupling agent are dissolved in a solvent. As the solvent, toluene, ethyl acetate, etc., or a mixed solvent thereof can be used. The dissolved resin forming solution is applied to a release sheet to volatilize the solvent. Thereby, the conductive adhesive film 15 was obtained.

[ production Process ]

Next, a process for manufacturing the solar cell module 1 will be described. The solar cell module 1 includes: the method for manufacturing the solar cell module includes a temporary bonding step of temporarily bonding a conductive adhesive film 15 to a bus bar electrode 11 and a back surface electrode 13, an arranging step of arranging the solar cells 2, a temporary pressure bonding step of thermally pressing the TAB wire 3 on the bus bar electrode 11 and the back surface electrode 13 at a low temperature and a low pressure on the conductive adhesive film 15, and a main pressure bonding step of thermally curing the conductive adhesive film 15 from the TAB wire 3 by thermal pressing to connect the TAB wire 3 to the bus bar electrode 11 and the back surface electrode 13.

First, the uncured conductive adhesive film 15 is temporarily attached to the bus bar electrode 11 and the back surface electrode 13 of each solar cell 2 (temporary attaching step). In the temporary bonding step of the conductive adhesive film 15, for example, the conductive adhesive film 15 wound around the reel body 27 is conveyed to a predetermined position on the front and back surfaces of the solar cell 2, and the conductive adhesive film 15 is temporarily bonded by being pressed by a temporary bonding head.

The conductive adhesive film 15 is heated by a temporary bonding head (not shown) for a predetermined time (for example, 1 to 5 seconds) at a temperature (for example, 40 to 60 ℃) at which the conductive adhesive film 15 is not solidified, thereby temporarily bonding the conductive adhesive film 15 to the solar battery cell 2. The solar battery cells 2 to which the conductive adhesive film 15 is temporarily attached are arranged in the order of series connection.

Next, the TAB wire 3 is temporarily bonded to the conductive adhesive film 15 for each solar cell 2 arranged at a predetermined position facing the pair of upper and lower temporary bonding heads 26 (temporary bonding step). At this time, as shown in fig. 2 and 8, one end 3a of the TAB wire 3 is temporarily pressure-bonded to the bus bar electrode 11 formed on the surface of one solar cell 2 previously performed, via the uncured conductive adhesive film 15 a. Further, the other end 3b of the TAB line 3 is temporarily pressure-bonded to the rear surface electrode 13 of another solar cell 2 which is continued later, via the uncured conductive adhesive film 15 b.

Similarly, one end 3a and the other end 3b of the TAB wire 3 are temporarily pressure-bonded to the bus bar electrode 11 formed on the front surface of the solar cell 2 and to the back surface electrode 13 of the solar cell 2 continuing from the solar cell 2 via an uncured conductive adhesive film 15. In this way, the adjacent solar cells 2 are connected in series by the TAB line 3.

As described above, in the TAB wire 3, the surface 30b on which the uneven portion 21 is formed is temporarily bonded to the bus bar electrode 11 at one end portion 3a, and the surface 20a on which the uneven portion 21 is formed is temporarily bonded to the rear surface electrode 13 at the other end portion 3 b.

In the temporary bonding step, the TAB wire 3 is temporarily bonded by the temporary bonding head 26. The temporary bonding head 26 is heated to a temperature (for example, about 70 to 100 ℃) at which the curing reaction of the conductive adhesive film 15 does not proceed, and the TAB line 3 is pressed against the pressing surface 26a for a predetermined time. Therefore, the conductive adhesive film 15 exhibits fluidity by the adhesive resin, and high adhesive strength is obtained, and the TAB line 3 is temporarily fixed to the bus bar electrode 11 and the back surface electrode 13.

Next, as shown in fig. 9, the plurality of solar battery cells 2 to which the TAB wire 3 is temporarily fixed are conveyed to a position directly below a pair of upper and lower heating and pressing heads 28, and after being supported, the TAB wire 3 is subjected to final pressure bonding to the bus bar electrode 11 and the rear surface electrode 13 of the solar battery cell 2 by the pressing surface 28a of the heating and pressing head 28, respectively, and the conductive adhesive film 15 is cured (final pressure bonding step).

At this time, among the plurality of solar cells 2, the solar cells 2 that are executed in advance are raised and lowered in synchronization by a pair of heating and pressing heads 28 provided above and below, and the TAB wire 3 is pressed at a predetermined pressure (for example, about 3MPa to 12 MPa). The heating and pressing head 28 is heated to a predetermined temperature (for example, about 180 to 220 ℃) at which the conductive adhesive film 15 is cured. Therefore, the adhesive resin is thermally cured in the conductive adhesive film 15, and the TAB line 3 is electrically and mechanically connected to the bus bar electrode 11 or the back surface electrode 13.

By such main pressure bonding, the conductive adhesive film 15 enters the concave portion 32 of the uneven portion 21 having the unevenness angle α of 10 to 50 °, and thereby the connection reliability between the bus bar electrode 11 and the back surface electrode 13 can be improved. Further, by increasing the particle trapping rate in the concave portion 32, high conduction reliability can be obtained.

When the TAB wire 3 is permanently pressed against the solar cell 2 that has been previously operated by the heat and pressure head 28, the pair of heat and pressure heads 28 are separated from each other by the TAB wire 3, and the solar cell 2 that continues thereafter is conveyed directly below the pair of heat and pressure heads 28. In this way, the solar cells 2 are conveyed one by one directly under the heat pressing head 28, and the TAB line 3 is bonded to the bus bar electrode 11 and the rear surface electrode 13 in this order and connected in series to the adjacent solar cells 2.

In this way, in the manufacturing process of the solar cell module 1, in order to connect the TAB line 3 to each of the bus bar electrodes 11 and the back surface electrodes 13 via the conductive adhesive film 15, although either Al or Ag can be used as the back surface electrodes 13 of the solar cells 2, since the use of the back surface Al collector electrodes as the back surface electrodes 13 makes it unnecessary to provide Ag electrodes for conventional solder connection, the manufacturing process of the solar cells is shortened, and there is an advantage in terms of production technology.

In the manufacturing process of the solar cell module 1, the TAB line 3 having the uneven portions 21 on both surfaces thereof is connected to the bus bar electrodes 11 and the rear surface electrodes 13 via a thermosetting resin. By applying the same pressure to the TAB line 3 having the same shape on both sides from both sides of the TAB line 3, the stress strain in the solar cell 2 can be minimized, and the cracking and bending of the solar cell 2 can be suppressed.

In the solar cell module 1, since the TAB line 3 having the symmetrical shape of the front surface and the back surface on which the uneven portions 21 are provided is provided, when the front surface and the back surface of the solar cell 2 are connected at the same time, stress strain generated on the front surface and the back surface of the solar cell 2 can be minimized, and therefore, the solar cell 2 can be prevented from being cracked or bent. For example, even when the solar battery cell 2 is very thin, the effect of suppressing the stress strain can be obtained.

In the solar cell module 1, by making the concave-convex angle α of the concave-convex portion 21 of the TAB line 3 10 to 50 °, it was found that the light blocking effect by the scattered light improves the power generation efficiency, and stable conduction reliability and connection reliability can be achieved on the front surface electrode side and the back surface electrode side.

Although the present embodiment has been described above, it is obvious that the present invention is not limited to the above-described embodiment, and various modifications are possible within a range not departing from the gist of the present invention.

In the above-described embodiment, the TAB line 3 is connected to each of the bus bar electrodes 11 and the back surface electrodes 13 by using the conductive adhesive film 15 as the adhesive resin material, but another adhesive resin material may be used. When a nonconductive adhesive film is used as the adhesive resin material, conduction can be achieved by bringing the convex portions 31 of the uneven portions 21 of the TAB wire 3 into direct contact with the bus bar electrodes 11 and the rear surface electrodes 13. Instead of providing these adhesive films, a paste adhesive such as a conductive paste or a non-conductive paste may be applied in an appropriate thickness. By applying the conductive paste or the non-conductive paste in an appropriate thickness, the same effects as those of the conductive adhesive film 15 and the non-conductive adhesive film can be obtained.

In the above-described embodiment, the solar cell module 1 including the single-sided light-receiving solar cell 2 has been described, but the present invention is not limited to this, and may be a solar cell module including a double-sided light-receiving solar cell 2A as shown in fig. 10, for example. The solar cell 2A includes finger electrodes 12 and bus bars 11 instead of the back surface electrode 13. The solar cell module including the solar cell 2A includes a front cover 7 instead of the back sheet 8.

In this way, in the solar cell module including the solar cell 2A of the both-side light receiving type, by using the TAB line 3 of the symmetrical shape of the front surface and the back surface, when both the front surface and the back surface of each solar cell 2A are simultaneously connected to the TAB line 3, stress strain generated on the front surface side and the back surface side of the solar cell 2 is suppressed to the minimum, and the occurrence of cracking or bending of the solar cell 2 can be prevented. Further, stable conduction reliability and connection reliability can be achieved on the front surface electrode (bus bar electrode 11, finger electrode 12) side and the back surface electrode 13 side. Further, by providing the TAB line 3 having the uneven portions 21 formed on both surfaces, it is possible to further improve the power generation efficiency.

Examples

[ examples ]

Next, specific examples of the present invention will be explained. The scope of the present invention is not limited to the following examples. In the present embodiment, as shown in fig. 2, TAB lines shown in examples 1 to 5 and comparative examples 1 to 5 below were connected to the solar cell 2.

(example 1)

First, a single-sided light-receiving solar battery cell is prepared. An uncured conductive adhesive film (trade name: SP100 series, manufactured by Sony chemical & information devices Co., Ltd.) was temporarily bonded to each of the bus bar electrode and the back surface electrode provided in the solar cell by heating and pressurizing the resultant with a temporary bonding head at a heating temperature of 180 ℃ and a pressure of 2MPa for 15 seconds. Next, a TAB line having concave and convex portions with a concave and convex angle α of 10 ° formed on both surfaces thereof was pressure-bonded to each of the conductive adhesive film temporarily attached to the bus bar electrode of the solar cell and the conductive adhesive film temporarily attached to the back surface electrode of the solar cell. In the pressure bonding, the pressure bonding head was heated and pressed at 180 ℃ and a pressure of 2MPa for 15 seconds.

(example 2)

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 20 ° formed on both surfaces was used instead of the TAB line in example 1.

(example 3)

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 30 ° formed on both surfaces was used instead of the TAB line in example 1.

(example 4)

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 40 ° formed on both surfaces was used instead of the TAB line in example 1.

(example 5)

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 50 ° formed on both surfaces was used instead of the TAB line in example 1.

Comparative example 1

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 5 ° formed on both surfaces was used instead of the TAB line in example 1.

Comparative example 2

The same process as in example 1 was performed except that a TAB line having concave and convex portions with a concave and convex angle α of 60 ° formed on both surfaces was used instead of the TAB line in example 1.

Comparative example 3

Instead of the TAB line of example 1, a TAB line having a concave-convex portion with a concave-convex angle α of 30 ° formed on one surface thereof was used. The surface of the TAB line connected to the bus bar electrode on which the uneven portion is formed is set as the light receiving surface side, and the surface of the TAB line connected to the back surface electrode on which the uneven portion is formed is opposed to the back surface electrode ("one surface (1)" in table 1). Except for this, the same treatment as in example 1 was performed.

Comparative example 4

Instead of the TAB line of example 1, a TAB line having a concave-convex portion with a concave-convex angle α of 30 ° formed on one surface thereof was used. The surface of the TAB line connected to the bus bar electrode on which the uneven portion is formed is opposed to the bus bar electrode, and the surface of the TAB line connected to the back surface electrode on the opposite side of the surface on which the uneven portion is formed is opposed to the back surface electrode ("one surface (2)" in table 1). Except for this, the same treatment as in example 1 was performed.

Comparative example 5

The same process as in example 1 was performed except that a TAB line having a planar shape with no uneven portions formed on both surfaces was used instead of the TAB line of example 1.

< evaluation of Power Generation efficiency >

The average power generation efficiency (%) of the solar cell after the TAB wire was connected was measured by a solar simulator (model PVS1116i-M (JIS C8913) manufactured by nippon electronics and electronics). The power generation efficiency was evaluated as ^ 16% or more, as ^ 15.75 to 16%, as ^ 15.6 to 15.75%, and as ^ 15.6% or less, as ^ x. The evaluation results are shown in [ Table 1 ].

< evaluation of connection reliability >

A 90 ° peel test (JIS K6854-1) was performed in which the TAB line was peeled in a 90 ° direction from the conductive adhesive film adhered to each of the bus bar electrode and the back surface electrode, and the peel strength (N/cm) was measured. Based on the measured peel strength, the connection reliability of each of the TAB line and the bus bar electrode and the TAB line and the back surface electrode was evaluated. The connection reliability was evaluated as "excellent" when the peel strength was 10N/cm or more, as "good" when 8 to 10N/cm, as "delta" when 6 to 8N/cm, and as "poor" when 6N/cm or less. The evaluation results are shown in [ Table 1 ].

< evaluation of bending amount >

In a state in which the solar cell was placed on a plane (a convex surface due to bending was placed on the lower side), the maximum value of the height (mm) from the plane among the four corners of the solar cell was measured as the bending amount (mm). The bending amount was evaluated as ∘ at 1mm or less, Δ at 1mm to 2.5mm, and × at 2.5mm or more. The evaluation results are shown in [ Table 1 ].

< comprehensive evaluation >

As the comprehensive evaluation, the examples that did not have the evaluation result of x and could be used without any problem in practice among the evaluation items of the power generation efficiency, the connection reliability, and the bending amount were evaluated as x. The evaluation results of the comprehensive evaluation are shown in [ Table 1 ].

TABLE 1

Example 1

Example 2

Example 3

Example 4

Example 5

Comparative example 1

Comparative example 2

Comparative example 3

Comparative example 4

Comparative example 5

Arrangement of bumps in TAB line

Two sides of the bag

Two sides of the bag

Two sides of the bag

Two sides of the bag

Two sides of the bag

Two sides of the bag

Two sides of the bag

Single side (1)

Single side (2)

Is free of

Angle of concavity and convexity alpha (°)

10

20

30

40

50

5

60

30

30

－

Efficiency of power generation

△

○

◎

○

△

×

×

◎

×

×

Connection reliability

△

○

○

◎

◎

×

◎

Light receiving surface

Back face is available

×

Amount of bending

○

○

○

○

○

○

○

×

×

○

Comprehensive evaluation

○

○

○

○

○

×

×

×

×

×

As shown in table 1, in examples 1 to 5 in which the concave-convex angle α is 10 ° to 50 °, the incident light is incident on the concave-convex portion of the concave-convex angle α, whereby the scattered light at a good scattering angle can be obtained, and the light blocking effect by the scattered light is found, and a high value can be obtained in the power generation efficiency. In particular, in example 3 in which the concave-convex angle α was 30 °, the best light blocking effect was found and the highest power generation efficiency was obtained.

In examples 1 to 5, the concave-convex angle α was set to 10 ° or more and 50 ° or less, so that the filling amount of the adhesive resin of the conductive adhesive film that flowed by heating and entered the recessed portion was sufficient, and the connection reliability between the TAB line and the bus bar electrode and between the TAB line and the back surface electrode was good. In particular, in examples 4 and 5 in which the concave-convex angle α was 40 ° or more, high connection reliability was obtained by obtaining a larger amount of adhesive filling in the concave portion.

In examples 1 to 5, since TAB lines having symmetrical shapes of the front and back surfaces were provided, the occurrence of warpage was minimized.

Thus, in examples 1 to 5, from the evaluation results of the power generation efficiency, the connection reliability, and the bending amount, a total evaluation result usable without practical problems was obtained.

In particular, in examples 2 to 4, since the concave-convex angle α is set to 20 ° or more and 40 ° or less, the scattering angle of the incident light can be set to a better value, and thus a higher value can be obtained in the power generation efficiency. Further, when the concave-convex angle is 20 °, the filling amount of the binder resin of the conductive adhesive film which flows by heating and enters the concave portion can be increased, and high connection reliability can be obtained.

On the other hand, in comparative examples 1, 2, 4, and 5, the power generation efficiency became a low value. This is considered because the concave-convex angle α of the concave-convex portions formed on both surfaces of the TAB line is excessively small in comparative example 1, the concave-convex angle α of the concave-convex portions formed on both surfaces of the TAB line is excessively large in comparative example 2, the surface of the planar shape of the TAB line is set to the light receiving surface side in comparative example 4, and the surface of the TAB line is set to the planar shape (the concave-convex angle α is 0 °) in comparative example 5, and thus the light blocking effect by the scattered light cannot be sufficiently found.

In comparative examples 1, 3 to 5, the connection reliability between the TAB line and the bus bar electrode and between the TAB line and the back surface electrode was not good. This is considered because, in comparative example 1, since the concave-convex angle α is too small, the filling amount of the binder resin of the conductive adhesive film flowing by heating and entering the concave portion is insufficient, and the connection reliability is not good.

In comparative example 3, since the surface of the TAB line surface in the planar shape is a planar surface, the amount of the adhesive resin applied cannot be obtained at all, and the reliability of connection between the TAB line on the light receiving surface side and the bus bar electrode is not good. In comparative example 4, since the surface of the side of the back electrode connected to the TAB line on the back surface side was a planar shape, the amount of the adhesive resin filled in the TAB line surface having the planar shape could not be obtained at all, and the connection reliability between the TAB line on the back surface side and the back electrode was not good.

In comparative example 5, since both surfaces of the TAB line have a planar shape, the amount of the adhesive resin filled in the TAB line surface having the planar shape cannot be obtained at all, and thus the connection reliability is not good at either of the bus electrode side and the back electrode side.

In comparative examples 3 and 4, it is considered that since TAB lines having asymmetric shapes on the front and back surfaces are connected, stress strain occurs on the bus bar electrode side and the back surface electrode side of the solar cell during TAB line connection, and the amount of bending is excessively large.

Description of the reference numerals

1a solar cell module comprising a plurality of solar cells,

2a solar cell unit, and a solar cell unit,

3a TAB line, a first electrode, a second electrode,

4, the battery strip is arranged in the groove,

5, the matrix is formed by the following steps,

10 a photoelectric conversion element for a semiconductor device,

11 a bus-bar electrode, wherein,

12 a pair of finger-shaped electrodes,

13 a back-side electrode, wherein the back-side electrode,

15a conductive adhesive film which is formed by laminating a plurality of films,

21 uneven portion.

Claims (4)

1. A solar cell module in which a front surface electrode of a predetermined solar cell among a plurality of solar cells and a rear surface electrode of another solar cell adjacent to the predetermined solar cell are connected by a TAB line,

the TAB line

Uneven portions formed on both the front and back surfaces, each of the uneven portions being formed by a plurality of projections and recesses alternately arranged in the width direction and continuing in the longitudinal direction,

one end of the electrode is connected to the front surface electrode, the other end of the electrode is connected to the back surface electrode via an adhesive resin material,

the concave-convex angle formed by a line segment connecting the vertex of the convex portion and the vertex of the concave portion adjacent to the convex portion and a line segment connecting the vertices of the concave portion adjacent to both sides of the convex portion is 10 DEG to 50 deg.

2. The solar cell module of claim 1,

the concave-convex angle is more than 20 degrees and less than 40 degrees.

3. The solar cell module of claim 2,

the adhesive resin material is a conductive adhesive film containing conductive particles or a non-conductive adhesive film containing no conductive particles.

4. A method for manufacturing a solar cell module in which a front surface electrode of a predetermined solar cell among a plurality of solar cells and a rear surface electrode of another solar cell adjacent to the predetermined solar cell are connected by a TAB line,

comprising: a pressure bonding step of pressure bonding the TAB line via an adhesive resin material to each of the front surface electrode and the back surface electrode of the solar cell,

wherein the TAB line has a plurality of convex and concave portions alternately arranged in the width direction and formed continuously in the longitudinal direction on both the front and back surfaces, and a convex-concave angle formed by a line segment connecting the apex of the convex portion and the apex of the concave portion adjacent to the convex portion and a line segment connecting the apexes of the concave portion adjacent to both sides of the convex portion is 10 DEG to 50 DEG,

in the pressure bonding step, one end of the TAB wire is connected to the front surface electrode, and the other end of the TAB wire is connected to the back surface electrode via an adhesive resin material.