Patent Publication Number: US-2017373210-A1

Title: Solar cell module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. continuation application of PCT International Patent Application Number PCT/JP2016/000752 filed on Feb. 15, 2016, claiming the benefit of priority of Japanese Patent Application Number 2015-072100 filed on Mar. 31, 2015, the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a solar cell module. 
     2. Description of the Related Art 
     In recent years, solar cell modules have been progressively developed as photoelectric conversion devices which convert light energy into electric energy. Solar cell modules can directly convert inexhaustible sunlight into electricity, which has less environmental impact than power generation using fossil fuels. Accordingly, such solar cell modules generate power cleanly, and thus are expected to provide new energy sources. 
     For example, a solar cell module has a structure in which solar cells are sealed by a filler, between a front surface shield and a back surface shield. In the solar cell module, the solar cells are disposed in a matrix. Each pair of adjacent solar cells among solar cells linearly aligned in either the row direction or the column direction are connected by a tab line to form a string. 
     Japanese Unexamined Patent Application Publication No. 2008-135654 proposes a solar cell module in which a connection layer made of resin containing electrically conductive particles is disposed between a tab line which connects two solar cells and a bus bar electrode formed on the surface of a solar cell. 
     SUMMARY 
     However, in a conventional solar cell module, stress may be applied to a tab line between solar cells due to expansion and contraction of the solar cells and the tab line that are caused by temperature cycling. 
     In view of this, the present disclosure has been conceived in order to address the above problem, and an object thereof is to provide a solar cell module which can reduce stress applied to a tab line. 
     In order to address the above problem, a solar cell module according to the present disclosure includes: two solar cells adjacent to each other in a direction parallel to a light-receiving surface of the solar cell module; a tab line which is disposed on a front surface of a first solar cell among the two solar cells and a back surface of a second solar cell among the two solar cells, and electrically connects the two solar cells; and bonding members which bond the tab line to the two solar cells, wherein bonding strength between the tab line and at least one of the two solar cells in a first edge area on a side electrically connected with the other of the two solar cells by the tab line is lower than bonding strength between the tab line and the at least one of the two solar cells in a central area. 
     The solar cell module according to the present disclosure reduces stress applied to a tab line. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The figures depict one or more implementations in accordance with the present teaching, by way of examples only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1  is a schematic plan view of a solar cell module according to Embodiment 1; 
         FIG. 2  is a plan view of a solar cell according to Embodiment 1; 
         FIG. 3  is a cross-sectional view illustrating a stack structure of the solar cell according to Embodiment 1; 
         FIG. 4  is a cross-sectional view of a structure of the solar cell module according to Embodiment 1 in the column direction; 
         FIG. 5A  is a structural cross-sectional view illustrating a flow of electric charges from received light in the solar cell according to Embodiment 1; 
         FIG. 5B  is a structural cross-sectional view illustrating a flow of electric charges from received light in a conventional solar cell; 
         FIG. 6  shows plan views illustrating an electrode configuration of the solar cell according to Embodiment 1 on a front surface side and a back surface side; 
         FIG. 7  shows plan views illustrating an electrode configuration of a solar cell according to Variation 1 of Embodiment 1 on a front surface side and a back surface side; 
         FIG. 8  shows plan views illustrating an electrode configuration of a solar cell according to Variation 2 of Embodiment 1 on a front surface side and a back surface side; 
         FIG. 9  shows plan views illustrating an electrode configuration of a solar cell according to Variation 3 of Embodiment 1 on a front surface side and a back surface side; 
         FIG. 10  is an explanatory diagram of effects of resistance loss depending on the electrode configuration according to Embodiment 1; 
         FIG. 11  shows plan views and a cross-sectional view illustrating an electrode configuration of a solar cell according to Embodiment 2; 
         FIG. 12  shows a plan view and a cross-sectional view illustrating an electrode configuration of a solar cell according to Variation 1 of Embodiment 2; 
         FIG. 13  shows plan views illustrating an electrode configuration of a solar cell according to Variation 2 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 14  shows plan views illustrating an electrode configuration of a solar cell according to Variation 3 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 15  shows plan views illustrating an electrode configuration of a solar cell according to Variation 4 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 16  shows plan views illustrating an electrode configuration of a solar cell according to Variation 5 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 17  shows plan views illustrating an electrode configuration of a solar cell according to Variation 6 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 18  shows plan views illustrating an electrode configuration of a solar cell according to Variation 7 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 19  shows plan views illustrating an electrode configuration of a solar cell according to Variation 8 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 20  shows plan views illustrating an electrode configuration of a solar cell according to Variation 9 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 21  shows plan views illustrating an electrode configuration of a solar cell according to Variation 10 of Embodiment 2 on a front surface side and a back surface side; 
         FIG. 22A  is a plan view illustrating an electrode configuration of a solar cell according to Variation 11 of Embodiment 2; and 
         FIG. 22B  is a plan view illustrating an electrode configuration of a solar cell according to Variation 12 of Embodiment 2. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The following describes in detail a solar cell module according to embodiments of the present disclosure with reference to the drawings. The embodiments described below each illustrate a particular example of the present disclosure. Thus, the numerical values, shapes, materials, elements, the arrangement and connection of the elements, and others indicated in the following embodiments are mere examples, and are not intended to limit the present disclosure. Therefore, among the elements in the following embodiments, elements not recited in any of the independent claims defining the most generic part of the present disclosure are described as arbitrary elements. 
     The drawings are schematic diagrams and do not necessarily give strict illustration. Throughout the drawings, the same sign is given to the same element. 
     In the written description, a “front surface” of a solar cell means a surface through which more light enters the solar cell than light that enters the solar cell through a “back surface” located on the opposite side of the front surface (more than 50% to 100% of light enters the solar cell through the front surface), and there is also a case where no light enters the solar cell from the “back surface” side. A “front surface” of a solar cell module means a surface located on a side facing the “front surface” of the solar cell and through which light enters, and the “back surface” means a surface located on the opposite side of the front surface. Furthermore, the statement such as “a second member is disposed on a first member” does not necessarily mean that the first member and the second member are in direct contact, unless specifically limited. Thus, this statement includes the case where another member is present between the first member and the second member. In addition, the statement “approximately XX” is intended to mean, when using “approximately the same” as an example, not only completely the same, but also something that can be recognized as substantially the same. 
     Embodiment 1 
     [1-1. Basic Configuration of Solar Cell Module] 
     An example of a basic configuration of a solar cell module according to the present embodiment is described with reference to  FIG. 1 . 
       FIG. 1  is a schematic plan view of solar cell module  1  according to Embodiment 1. Solar cell module  1  illustrated in  FIG. 1  includes solar cells  11 , tab lines  20 , connecting lines  30 , and frame  50 . 
     Solar cells  11  are disposed two dimensionally on a light receiving surface of solar cell module  1 , and are plate-like photovoltaic cells which generate power by being irradiated with light. 
     Tab line  20  is a wiring member which is disposed on the surfaces of solar cells  11 , and electrically connects solar cells  11  adjacent in the column direction. Note that tab line  20  may have a light diffusing shape on the light entering side. The light diffusing shape is a shape having a light diffusing function. The light diffusing shape diffuses, on the surface of tab line  20 , light which has fallen on tab line  20 , and causes the diffused light to be redistributed to solar cell  11 . 
     Connecting line  30  is a wiring member which connects solar cell strings. Note that a solar cell string is an aggregate of solar cells  11  disposed in the column direction and connected by tab lines  20 . Note that connecting line  30  may have the light diffusing shape on a surface on the light entering side. Accordingly, light which has entered between solar cell  11  and frame  50  can be diffused on the surface of connecting line  30 , and the diffused light can be redistributed to solar cell  11 . 
     Frame  50  is an outer frame member which covers a perimeter portion of a panel on which solar cells  11  are two-dimensionally disposed. 
     Although not illustrated, a light diffusing member may be disposed between adjacent solar cells  11 . Accordingly, light which has entered a space between solar cells  11  can be redistributed to solar cells  11 , and thus light concentrating efficiency of solar cells  11  improves. Accordingly, the photoelectric conversion efficiency of the entire solar cell module can be improved. 
     [1-2. Structure of Solar Cell] 
     A description of a structure of solar cell  11  which is a main component of solar cell module  1  is given. 
       FIG. 2  is a plan view of solar cell  11  according to Embodiment 1. As illustrated in  FIG. 2 , solar cell  11  is approximately square in the plan view. For example, solar cell  11  has a length of 125 mm, a width of 125 mm, and a thickness of 200 μm. On a surface of solar cell  11 , bus bar electrodes  112  in stripes are formed in parallel to one another, and finger electrodes  111  in stripes are formed in parallel to one another, perpendicularly to bus bar electrodes  112 . Bus bar electrodes  112  and finger electrodes  111  constitute collector electrode  110 . Collector electrode  110  is formed using an electrically conductive paste which contains electrically conductive particles such as Ag (silver), for example. Note that the line width of bus bar electrodes  112  is, for example, 150 μm, and the line width of finger electrodes  111  is, for example, 100 μm. The spacing between finger electrodes  111  is 2 mm, for example. Tab lines  20  are bonded onto bus bar electrodes  112 . 
       FIG. 3  is a cross-sectional view illustrating a stack structure of solar cell  11  according to Embodiment 1. Note that  FIG. 3  is a cross-sectional view of solar cell  11  taken along III-III in  FIG. 2 . As illustrated in  FIG. 3 , i-type amorphous silicon film  121  and p-type amorphous silicon film  122  are formed in the stated order on the principal surface of n-type monocrystalline silicon wafer  101 . N-type monocrystalline silicon wafer  101 , i-type amorphous silicon film  121 , and p-type amorphous silicon film  122  form a photoelectric conversion layer, and n-type monocrystalline silicon wafer  101  serves as a main power generation layer. Furthermore, light-receiving surface electrode  102  is formed on p-type amorphous silicon film  122 . As illustrated in  FIG. 2 , collector electrode  110  constituted by bus bar electrodes  112  and finger electrodes  111  is formed on light-receiving surface electrode  102 . Note that in  FIG. 3 , only finger electrodes  111  of collector electrode  110  are illustrated. 
     I-type amorphous silicon film  123  and n-type amorphous silicon film  124  are formed in this order on the back surface of n-type monocrystalline silicon wafer  101 . Furthermore, light-receiving surface electrode  103  is formed on n-type amorphous silicon film  124 , and collector electrode  110  constituted by bus bar electrodes  112  and finger electrodes  111  is formed on light-receiving surface electrode  103 . 
     Note that p-type amorphous silicon film  122  may be formed on the back surface side of n-type monocrystalline silicon wafer  101 , and n-type amorphous silicon film  124  may be formed on the light-receiving surface side of n-type monocrystalline silicon wafer  101 . 
     Collector electrode  110  may be formed by a printing method such as, for example, screen printing, using a thermosetting, electrically conductive resin paste obtained using a resin material as a binder and electrically conductive particles such as silver particles as filler. 
     Note that as illustrated in  FIG. 3 , the spacing between finger electrodes  111  on the back surface may be smaller than the spacing between finger electrodes  111  on the front surface. In other words, the number of finger electrodes  111  on the back surface may be greater than the number of finger electrodes on the front surface. Specifically, the surface area occupancy of the collector electrode formed on the back surface may be higher than the surface area occupancy of the collector electrode formed on the front surface. Here, the surface area occupancy of the collector electrode is a proportion of a total area of bus bar electrodes  112  and finger electrodes  111  in a plan view with respect to the area of solar cell  11  in the plan view. 
     In the case of the above arrangement of the electrodes on the back surface, the efficiency of collecting current on the back surface increases, while more light is prevented from entering through the back surface than light prevented from entering through the front surface. However, solar cell  11  according to the present embodiment is a mono-facial element whose light-receiving surface is a front surface, and thus an increase in the current collecting efficiency on the back surface has greater influence than an increase in the amount of light prevented from entering through the back surface. Accordingly, advantageous effects of collecting current achieved by solar cell  11  can be improved. 
     Solar cell  11  according to the present embodiment has a structure in which i-type amorphous silicon film  121  is included between n-type monocrystalline silicon wafer  101  and p-type amorphous silicon film  122 , and i-type amorphous silicon film  123  is included between n-type monocrystalline silicon wafer  101  and n-type amorphous silicon film  124 , in order to improve p-n junction properties. 
     Solar cell  11  according to the present embodiment is a mono-facial element, and light-receiving surface electrode  102  on the front surface side of n-type monocrystalline silicon wafer  101  serves as a light-receiving surface. Charge carriers generated in n-type monocrystalline silicon wafer  101  are diffused as photocurrent to light-receiving surface electrodes  102  and  103  on the front surface side and the back surface side, and collected by collector electrodes  110 . 
     Light-receiving surface electrodes  102  and  103  are, for example, transparent electrodes made of indium tin oxide (ITO), tin oxide (SnO 2 ), and zinc oxide (ZnO), for instance. Note that light-receiving surface electrode  103  on the back surface side may be a metal electrode which is not transparent. Further, an electrode formed on the entire surface on light-receiving surface electrode  103  may be used as a collector electrode on the back surface side, instead of collector electrode  110 . 
     Note that the solar cell according to the present embodiment may be a bifacial element. In this case, light-receiving surface electrode  102  on the front surface side of n-type monocrystalline silicon wafer  101  and light-receiving surface electrode  103  on the back surface side of n-type monocrystalline silicon wafer  101  both serve as light-receiving surfaces. Charge carriers generated in n-type monocrystalline silicon wafer  101  are diffused as photoelectric current to light-receiving surface electrodes  102  and  103  on the front surface side and the back surface side, and collected by collector electrodes  110 . Light-receiving surface electrodes  102  and  103  are transparent electrodes. 
     [1-3. Structure of Solar Cell Module] 
     The following describes a specific structure of solar cell module  1  according to the present embodiment. 
       FIG. 4  is a cross-sectional view of a structure of the solar cell module according to Embodiment 1 in the column direction. Specifically,  FIG. 4  is a cross-sectional view of solar cell module  1  taken along line IV-IV in  FIG. 1 . Solar cell module  1  illustrated in  FIG. 4  includes solar cells  11 , tab lines  20 , electrically conductive bonding members  40 A and  40 B, front surface filler  70 A, back surface filler  70 B, front surface shield  80 , and back surface shield  90 . 
     Tab lines  20  are electrically conductive elongated lines, and are ribbon-shaped metallic foil, for example. Tab lines  20  can be produced by cutting, for example, metallic foil, such as copper foil or silver foil having surfaces entirely covered with solder, silver, or the like into strips having a predetermined length. In two solar cells  11  adjacent in the column direction, tab line  20  disposed on the front surface of one of solar cells  11  is also disposed on the back surface of the other of solar cells  11 . More specifically, the undersurface of tab line  20  at an end portion is connected with bus bar electrode  112  (see  FIG. 2 ) on the front surface side of one of solar cells  11 . The upper surface of tab line  20  at the other end portion is connected with a bus bar electrode (not illustrated) on the back surface side of the other of solar cells  11 . Accordingly, a solar cell string made up of solar cells  11  disposed in the column direction has a configuration in which solar cells  11  are connected in series in the column direction. 
     Tab lines  20  and bus bar electrodes  112  (see  FIG. 2 ) are connected by electrically conductive bonding members  40 A and  40 B. Stated differently, tab line  20  is connected with solar cell  11  via an electrically conductive bonding member. 
     As electrically conductive bonding members  40 A and  40 B, an electrically conductive adhesive paste, an electrically conductive glue film, or an anisotropic electrically conductive film can be used, for example. Electrically conductive adhesive paste is a pasty adhesive obtained by dispersing electrically conductive particles into a thermosetting adhesive resin material such as an epoxy resin, an acrylic resin, or a urethane resin, for example. An electrically conductive glue film and an anisotropic electrically conductive film are obtained by dispersing electrically conductive particles into a thermosetting adhesive resin material and forming the material into films. 
     Note that electrically conductive bonding members  40 A and  40 B may be solder material, rather than the electrically conductive adhesive mentioned above as an example. Furthermore, a resin adhesive which does not include electrically conductive particles may be used, instead of the electrically conductive adhesive. In this case, by appropriately designing the thickness of an applied resin adhesive, a resin adhesive softens when pressure is applied for thermo compression bonding, and consequently the surface of bus bar electrode  112  and tab line  20  are brought into direct contact and electrically connected. 
     As illustrated in  FIG. 4 , front surface shield  80  is disposed on the front surface side of solar cells  11 , and back surface shield  90  is disposed on the back surface side. Front surface filler  70 A is included between a plane which includes solar cells  11  and front surface shield  80 , and back surface filler  70 B is included between a plane which includes solar cells  11  and back surface shield  90 . Front surface shield  80  and back surface shield  90  are fixed by front surface filler  70 A and back surface filler  70 B, respectively. 
     Front surface shield  80  is a shield disposed on the front surface side of solar cell  11 . Front surface shield  80  protects the inside of solar cell module  1  from rainstorm, external shock, fire, and so on, and is a member for securing long term reliability against outdoor exposure of solar cell module  1 . From this viewpoint, for example, light-transmitting waterproof glass, or a light-transmitting waterproof hard resin member having a film or plate shape, for instance, can be used for front surface shield  80 . 
     Back surface shield  90  is a shield disposed on the back surface side of solar cell  11 . Back surface shield  90  is a member which protects the back surface of solar cell module  1  from the outside environment, and for example, a laminated film which has a structure in which a resin film such as a polyethylene terephthalate film or an Al foil is sandwiched by resin films. 
     Front surface filler  70 A fills a space between front surface shield  80  and solar cells  11 . Back surface filler  70 B fills a space between back surface shield  90  and solar cells  11 . Front surface filler  70 A and back surface filler  70 B have a sealing function for separating solar cells  11  from the outside environment. Disposing front surface filler  70 A and back surface filler  70 B secures high heat resistance and high moisture resistance of solar cell module  1  which is assumed to be installed outside. 
     Front surface filler  70 A is made of a light-transmitting polymer material which has a sealing function. An example of the polymer material of front surface filler  70 A is a light-transmitting resin material such as ethylene vinyl acetate (EVA). 
     Back surface filler  70 B is made of a polymer material having a sealing function. Here, back surface filler  70 B is subjected to white processing. An example of the polymer material for back surface filler  70 B is a resin material which includes EVA that has been subjected to white processing. 
     Note that front surface filler  70 A and back surface filler  70 B may be based on the same material, in order to simplify a manufacturing process and the adhesion at the interface between front surface filler  70 A and back surface filler  70 B. Front surface filler  70 A and back surface filler  70 B are formed by performing lamination processing on (laminating) two resin sheets (light-transmitting EVA sheet and EVA sheet that has been subjected to white processing) between which solar cells  11  (cell strings) are disposed. 
     [1-4. Bonding Structure of Tab Line and Solar Cell] 
       FIG. 5A  is a structural cross-sectional view illustrating a flow of electric charges from received light in solar cell  11  according to Embodiment 1. More specifically,  FIG. 5A  is an enlarged cross-sectional view of a portion around the front surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . As illustrated in  FIG. 5A , bus bar electrode  112  and tab line  20  are bonded to each other by electrically conductive bonding member  40 A. 
       FIG. 5B  is a structural cross-sectional view illustrating a flow of electric charges from received light in a conventional solar cell. As illustrated in  FIG. 5B , in the conventional solar cell module, solar cell  11  and tab line  920  are uniformly bonded to each other on the entirety of solar cell  11  in the longitudinal direction of tab line  920 , via electrically conductive bonding member  940 A. Accordingly, stress may be applied to tab line  920  between solar cells by repeated expansion and contraction of solar cell  11  and tab line  920  due to temperature cycling. 
     On the other hand, a feature of solar cell module  1  according to the present embodiment is that the bonding strength between solar cell  11  and tab line  20  in edge region Ap on a side where tab line  20  is formed of solar cell  11  is lower than the bonding strength between solar cell  11  and tab line  20  in central area Ac of solar cell  11 . Since the bonding strength is set as stated above, even if solar cell  11  and tab line  20  repeatedly expand and contract due to temperature cycling, stress applied to tab line  20  between solar cells can be reduced. Here, edge area Ap is a first edge area of a perimeter area of solar cell  11 , which is on a side where solar cell  11  is electrically connected with another solar cell  11  by tab line  20 . 
     The above description is focused on edge area Ap of the front surface of solar cell  11  on a side where tab line  20  is formed, yet the bonding strength of tab line  20  on the back surface in edge area Ap on a side where tab line  20  is formed may be lower than the bonding strength in central area Ac. On only the front surface side, or on only the back surface side, or even on both sides, the bonding strength in edge area Ap on a side where tab line  20  is formed may be lower than the bonding strength in central area Ac. Furthermore, the bonding strength also in an edge area on a side where tab line  20  is not formed in addition to the side where tab line  20  is formed may be lower than central area Ac. In this case, for example, even when a solar cell is disposed upside down, advantageous effects of the present disclosure can be achieved, and thus yield when creating modules is expected to improve. Hereinafter, edge area Ap indicates an edge area of a front surface or a back surface on a side where tab line  20  is formed. 
     Note that due to a relation of the bonding strength in edge area Ap and  20  central area Ac, solar cell  11  and tab line  20  in central area Ac are bonded to each other in an electrically conductive state via bonding portion  40 P, whereas solar cell  11  and tab line  20  in edge area Ap are bonded to each other in an electrically nonconductive state via bonding portion  40 N. Accordingly, electric charges from received light which are collected by finger electrodes  111   p  formed  25  in edge area Ap are not transferred to tab line  20  via bonding portion  40 N immediately above. However, solar cell module  1  according to the present embodiment has a configuration of efficiently collecting electric charges from received light which are collected in edge area Ap, via bus bar electrode  112  and bonding portion  40 P in central area Ac. 
     The following describes in detail a configuration of improving efficiency of collecting current by collector electrode  110  while reducing stress applied to tab line  20 . 
     [1-5. Configuration of Collector Electrode According to Embodiment 1] 
       FIG. 6  shows plan views illustrating an electrode configuration of solar cell  11  according to Embodiment 1 on a front surface side and a back surface side. More specifically,  FIG. 6  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . 
     As illustrated in  FIG. 6 , bus bar electrode  112 S and finger electrodes  111 C perpendicular to bus bar electrode  112 S and parallel to one another are disposed in central area Ac on the front surface of solar cell  11 . Electrically conductive bonding member  40 A which bonds tab line  20  to bus bar electrode  112 S is disposed in central area Ac on the front surface of solar cell  11 . Note that short electrode groups for securing the bonding strength between tab line  20  and solar cell  11  are disposed between finger electrodes  111 C. Bus bar electrode  112 S and finger electrodes  111 P perpendicular to bus bar electrode  112 S and parallel to one another are disposed in edge area Ap on the front surface of solar cell  11 . 
     On the back surface of solar cell  11 , bus bar electrode  112 R and finger electrodes  111 C perpendicular to bus bar electrode  112 R and parallel to one another are disposed in central area Ac. Electrically conductive bonding member  40 A which bonds tab line  20  to bus bar electrode  112 R is disposed in central area Ac on the back surface of solar cell  11 . Bus bar electrode  112 R and finger electrodes  111 P and finger electrode  111 PR which are perpendicular to bus bar electrode  112 R and parallel to one another are disposed in edge area Ap on the back surface of solar cell  11 . Finger electrode  111 PR is formed closest to the edge among finger electrodes  111 P disposed in edge area Ap on the back surface. Note that a plurality of finger electrodes  111 PR may be disposed. The spacing between finger electrodes  111 PR and the spacing between finger electrode  111 PR and another finger electrode may be different from the spacing between finger electrodes  111 C and the spacing between finger electrodes  111 P. 
     Note that in the present embodiment and the variations described below, finger electrodes cross a bus bar electrode in a plan view, and disposed approximately parallel to one another. Accordingly, the finger electrodes have a function of transferring electric charges from received light generated by solar cell  11  to the bus bar electrode. 
     In the present embodiment and the variations described below, a bus bar electrode is disposed in central area Ac, crossing finger electrodes, and bonded to tab line  20  via electrically conductive bonding member  40 A in central area Ac. Accordingly, the bus bar electrode has a function of transferring electric charges from received light which are collected by the finger electrodes to tab line  20 . The bus bar electrode is defined to include an electrode which is directly connected with the bus bar electrode disposed in central area Ac and crosses a finger electrode in edge area Ap, and exclude an electrode in edge area Ap connected with the bus bar electrode disposed in central area Ac via a line extending in a direction in which a finger electrode is formed. 
     Here, bus bar electrodes  112 S and  112 R are formed in both edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A are disposed only in central area Ac among edge area Ap and central area Ac. Specifically, the lengths of electrically conductive bonding members  40 A in the longitudinal direction of tab lines  20  are shorter than the lengths of bus bar electrodes  112 S and  112 R in the longitudinal direction of tab lines  20 . 
     Accordingly, tab lines  20  are bonded to solar cell  11  only in central area Ac, and thus stress applied to tab lines  20  between solar cells  11  can be reduced even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling. 
     Bus bar electrode  112 R formed on the back surface is longer toward the edge of solar cell  11  than bus bar electrode  112 S formed on the front surface is. Finger electrode  111 PR formed on the back surface is closer to the edge of solar cell  11  than outermost finger electrode  111 P among finger electrodes formed on the front surface. In the case of the above electrode arrangement on the back surface, the current collecting efficiency on the back surface increases, but more light is prevented from entering through the back surface than light prevented from entering through the front surface. However, solar cell  11  according to the present embodiment is a mono-facial element whose front surface is the light-receiving surface, and thus an increase in the current collecting efficiency on the back surface gives more influence than the influence of an increase in the amount of light prevented from entering through the back surface. This allows solar cell  11  to yield more advantageous effects of collecting current. Note that a plurality of finger electrodes  111 PR may be disposed. The spacing between finger electrodes  111 PR and the spacing between finger electrode  111 PR and another finger electrode may be different from the spacing between finger electrodes  111 C and the spacing between finger electrodes  111 P. 
     [1-6. Configuration of Collector Electrode According to Variation 1 of Embodiment 1] 
       FIG. 7  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 1 of Embodiment 1 on a front surface side and a back surface side. More specifically,  FIG. 7  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  illustrated in  FIG. 6 , only in the configuration of bus bar electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 6  while a description of the same points is omitted. 
     As illustrated in  FIG. 7 , bus bar electrode  112 S according to this variation includes two electrodes parallel to each other in edge area Ap. The widths of the two electrodes are each approximately the same as the width of bus bar electrode  112 S in central area Ac. Specifically, a resistance per unit length of bus bar electrode  112 S in edge area Ap is lower than the resistance per unit length of bus bar electrode  112 S in central area Ap. The same applies to bus bar electrode  112 R according to this variation, and a resistance per unit length of bus bar electrode  112 R in edge area Ap is lower than a resistance per unit length of bus bar electrode  112 R in central area Ap. 
     As illustrated in  FIG. 7 , bus bar electrodes  112 S and  112 R are not bonded to tab lines  20  in edge area Ap. Electric charges from received light collected by all finger electrodes  111 P disposed in edge area Ap are transferred to tab lines  20  via the bus bar electrodes in edge area Ap. According to the electrode configuration described above, the electric charges from received light collected in edge area Ap are transferred to tab lines  20  via the bus bar electrodes in edge area Ap where resistance loss is relatively low, and thus the current collecting efficiency of solar cell  11  can be increased. 
     Note that in this variation, a resistance per unit length of bus bar electrodes  112 S and  112 R in edge area Ap is each decreased by disposing two parallel electrodes in edge area Ap, yet the present disclosure is not limited to this. For example, the bus bar electrodes in edge area Ap may be each achieved by using one electrode wider than the bus bar electrode in central area Ac, rather than by using two parallel electrodes. The thickness of a bus bar electrode in edge area Ap may be greater than the thickness of the bus bar electrode in central area Ac. 
     [1-7. Configuration of Collector Electrode According to Variation 2 of Embodiment 1] 
       FIG. 8  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 2 of Embodiment 1 on a front surface side and a back surface side. More specifically,  FIG. 8  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  illustrated in  FIG. 6 , only in the configuration of bus bar electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 6  while a description of the same points is omitted. 
     As illustrated in  FIG. 8 , bus bar electrode  112 S according to this variation has a greater width in edge area Ap than the width in central area Ac. In edge area Ap, width W 112P1  of bus bar electrode  112 S in an area closer to central area Ac is greater than width W 112P2  of bus bar electrode  112 S in an area farther from central area Ac than the area closer to central area Ac is. The same applies to bus bar electrode  112 R on the back surface, and in edge area Ap, the width of bus bar electrode  112 R in an area closer to central area Ac is greater than the width of bus bar electrode  112 R in an area farther from central area Ac than the area closer to central area Ac is. Stated differently, in edge area Ap, resistances per unit length of portions of bus bar electrodes  112 S and  112 R closer to central area Ac are lower than resistances per unit length of portions of bus bar electrodes  112 S and  112 R farther from central area Ac. 
     As illustrated in  FIG. 8 , bus bar electrodes  112 S and  112 R are not bonded to tab lines  20  in edge area Ap. Thus, electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap are transferred to tab lines  20  via the bus bar electrodes in edge area Ap. According to the electrode configuration described above, the electric charges from received light collected in edge area Ap are transferred to tab lines  20  via the bus bar electrodes in edge area Ap where resistance loss is relatively low. Thus, the current collecting efficiency of solar cell  11  can be improved. Furthermore, with regard to the bus bar electrodes in edge area Ap, the amount of electric charges from received light collected in edge area Ap increases toward central area Ac. In view of this, in edge area Ap, resistances per unit length of portions of the bus bar electrodes closer to central area Ac are lower than resistances per unit length of portions of the bus bar electrodes farther from central area Ac. Accordingly, the resistance loss in edge area Ap can be decreased, and the current collecting efficiency of solar cell  11  is further improved. 
     [1-8. Configuration of Collector Electrode According to Variation 3 of Embodiment 1] 
       FIG. 9  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 3 of Embodiment 1 on a front surface side and a back surface side. More specifically,  FIG. 9  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 8 , only in the configuration of bus bar electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 6  while a description of the same points is omitted. 
     As illustrated in  FIG. 9 , bus bar electrode  112 S according to this variation has a greater width in edge area Ap than the width in central area Ac. In edge area Ap, width W 112P1  of bus bar electrode  112 S in an area closer to central area Ac is greater than width W 12P2  of bus bar electrode  112 S in an area farther from central area Ac than the area closer to central area Ac is. Bus bar electrode  112 S in edge area Ap has an inversely tapered shape gradually wider toward central area Ac in the plan view. Furthermore, the same applies to bus bar electrode  112 R on the back surface, and bus bar electrode  112 R in edge area Ap has an inversely tapered shape gradually wider toward central area Ac in the plan view. 
     According to this, similarly to solar cell  11  according to Variation 2, electric charges from received light collected in edge area Ap are transferred to tab lines  20  via the bus bar electrodes in edge area Ap where resistance loss is relatively small, and thus current collecting efficiency of solar cell  11  is improved. Furthermore, resistances per unit length of the bus bar electrodes in edge area Ap are gradually decreased toward central area Ac, and thus resistance loss in edge area Ap can be more effectively decreased. Accordingly, the current collecting efficiency of solar cell  11  is further improved. 
     [1-9. Resistance Loss Depending on Configuration of Collector Electrode According to Embodiment 1] 
       FIG. 10  illustrates effects of resistance loss depending on an electrode configuration according to Embodiment 1. More specifically,  FIG. 10  illustrates, on the left, an enlarged plan view showing an electrode configuration on the front surface of solar cell  11  and, on the right, a graph showing a relation between the width of a bus bar electrode and resistance loss. 
     In the plan view in  FIG. 10 , bus bar electrode  112  is formed on both edge area Ap and central area Ac. Electrically conductive bonding member  40 A is, however, disposed only in central area Ac, among edge area Ap and central area Ac. Specifically, the longitudinal length of electrically conductive bonding member  40 A is shorter than the length of bus bar electrode  112 . Here, the width of bus bar electrode  112  in edge area Ap is W 112P , and the length of bus bar electrode  112  in edge area Ap is L 112P . 
     The graph in  FIG. 10  shows a relation between resistance loss that occurs in bus bar electrode  112  and length L 112P  of bus bar electrode  112  when electrode width W 112P  is changed. Note that a rate of increase in resistance loss of bus bar electrode  112  indicated by the vertical axis is a proportion to resistance loss when the width of bus bar electrode  112  is uniform along the longitudinal direction. As illustrated in the graph in  FIG. 10 , the longer length L 112P  of bus bar electrode  112  in edge area Ap not connected with tab line  20  is, the greater the resistance loss that occurs in bus bar electrode  112  is. In contrast, the greater width W 112P  of bus bar electrode  112  in edge area Ap not connected with tab line  20  is, the less the resistance loss that occurs in bus bar electrode  112  is. 
     In the present embodiment, in order to reduce stress applied to tab line  20  due to temperature cycling, the longitudinal length of electrically conductive bonding member  40 A is shorter than the length of bus bar electrode  112 . Instead, length L 112P  of bus bar electrode  112  not connected to tab line  20  is increased, and thus the resistance loss that occurs in bus bar electrode  112  increases. In contrast, resistance loss that occurs in bus bar electrode  112  can be reduced by making width W 112P  of bus bar electrode  112  in edge area Ap, which is not connected with tab line  20 , greater than the width of bus bar electrode  112  in central area Ac. Thus, current collecting efficiency can be improved while reducing stress applied to tab line  20  between solar cells  11 . 
     Embodiment 2 
     A solar cell module according to the present embodiment has a feature that the bonding strength between solar cell  11  and tab line  20  in edge area Ap of solar cell  11  is lower than the bonding strength between solar cell  11  and tab line  20  in central area Ac of solar cell  11 , similarly to the solar cell module according to the above embodiment. In order to achieve this, the longitudinal length of electrically conductive bonding member  40 A is made shorter than the length of bus bar electrode  112  in Embodiment 1, whereas in the present embodiment, in the longitudinal direction of tab line  20 , the shortest distance between the edge of solar cell  11  and a finger electrode closest to the edge of solar cell  11  on a side where tab line  20  is formed is made shorter than the distance between the edge of solar cell  11  and an end of the bus bar electrode on the side where tab line  20  is formed. Accordingly, even if electrically conductive bonding member  40 A is present in edge area Ap, an area where electrically conductive bonding member  40 A and an electrode are bonded to each other is decreased, and thus the bonding strength in edge area Ap can be decreased. Thus, the bonding strength between solar cell  11  and tab line  20  can be decreased irrespective of the length of electrically conductive bonding member  40 A in the longitudinal direction. In the following embodiments, a bonding length in the longitudinal direction of tab line  20  along which bus bar electrode  112  and tab line  20  are bonded together is shorter than the length of electrically conductive bonding member  40 A in the longitudinal direction. 
     The basic configuration, a cross-sectional configuration, and others of the solar cell module according to the present embodiment are the same as those in Embodiment 1, and thus a description thereof is omitted. The following gives a description focusing on an electrode configuration of solar cell  11  different from the electrode configuration in Embodiment 1. 
     [2-1. Configuration of Collector Electrode According to Embodiment 2] 
       FIG. 11  shows plan views and a cross-sectional view illustrating an electrode configuration of solar cell  11  according to Embodiment 2. More specifically,  FIG. 11  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 , and an enlarged cross-sectional view of a portion around the front  10  surface of solar cell  11 . 
     As illustrated in the cross-sectional view in  FIG. 11 , electrically conductive bonding members  40 A bond tab lines  20  to solar cell  11  by bonding tab lines  20  to bus bar electrodes  112 . As illustrated in the plan view on the front surface side and the plan view on the back surface side in  FIG. 11 , bus bar electrode  112  and finger electrodes  111 C perpendicular to bus bar electrodes  112  and parallel to one another are disposed in central area Ac of solar cell  11 . Note that short electrode groups for securing the bonding strength between solar cell  11  and tab lines  20  are disposed between finger electrodes  111 C. 
     Note that in the present embodiment the variations thereof described later, finger electrodes are disposed approximately parallel to one another in a direction crossing a bus bar electrode in a plan view. Accordingly, the finger electrodes have a function of transferring, to the bus bar electrode, electric charges from received light which are generated by solar cell  11 . 
     In the present embodiment and the variations described later, a bus bar electrode crosses finger electrodes at least in central area Ac, and bonded to tab line  20  in central area Ac. Accordingly, the bus bar electrode have a function of transferring electric charges from received light collected by the finger electrodes to tab line  20 . The bus bar electrode is defined to include an electrode which is directly connected with the bus bar electrode disposed in central area Ac and crosses a finger electrode in edge area Ap, and exclude an electrode in edge area Ap connected with the bus bar electrode disposed in central area Ac via a line extending in a direction in which a finger electrode is formed. 
     Here, bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In this case, in edge area Ap, shortest distance Xf between the edge of solar cell  11  and outermost finger electrode  111 P is shorter than distance Xb between the edge of solar cell  11  and bus bar electrode  112 , in the longitudinal direction of tab line  20 . Electrically conductive bonding members  40 A are, however, disposed in both edge area Ap and central area Ac. Specifically, bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together is shorter than the lengths of electrically conductive bonding members  40 A in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A in the longitudinal direction. Accordingly, even if electrically conductive bonding members  40 A are present in edge area Ap, and also even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in an edge area on a side opposite the edge area Ap. Even in this case, the same advantageous effects as those in the above are achieved. 
     As illustrated in the plan views in  FIG. 11 , finger electrodes  111 P not directly connected with bus bar electrodes  112  and connection electrodes  113 A which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . Here, connection electrodes  113 A are not in contact with electrically conductive bonding members  40 A. Such an arrangement of connection electrodes  113 A allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. Connection electrodes  113 A are not in contact with electrically conductive bonding members  40 A, and thus the bonding strength between tab lines  20  and solar cell  11  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     With regard to finger electrodes  111 C connected with connection electrodes  113 A, width W 111B  of electrode portions  111 B between bus bar electrodes  112  and connecting points with connection electrodes  113 A is greater than width W 111C  of other finger electrodes  111 C. Electrode portions  111 B each transfer electric charges from received light collected by two or more finger electrodes, and thus resistance loss will be high if electrode portions  111 B have normal electrode width W 111C . To address this, electrode portions  111 B have width W 111B  that is greater than width W 111C , and thus current collecting efficiency in and in the vicinity of edge area Ap can be improved. 
     Furthermore, as illustrated in the plan views in  FIG. 11 , in edge area Ap of solar cell  11 , support electrodes  114 A which support tab lines  20  are formed in the endmost portions where electrically conductive bonding members  40 A are not disposed, in the longitudinal direction of tab line  20 . Here, as illustrated in the cross-sectional view in  FIG. 11 , the thickness (height) of support electrode  114 A may be greater than the thickness of electrically conductive bonding member  40 A. Accordingly, as illustrated in the cross-sectional view in  FIG. 11 , a space is present between electrically conductive bonding member  40 A and tab line  20  in edge area Ap, and thus electrically conductive bonding member  40 A and tab line  20  are prevented from being in contact. Therefore, deterioration of the shape of tab lines  20  in the edge portion of solar cell  11  can be prevented. 
     Finger electrodes  111 PR are disposed in edge area Ap on the back surface of solar cell  11 . Finger electrodes  111 PR are outermost finger electrodes among finger electrodes  111 P disposed in edge area Ap on the back surface. Note that a plurality of finger electrodes  111 PR may be disposed on one or both sides of tab line  20 . The spacing between finger electrodes  111 PR and the spacing between finger electrode  111 PR and another finger electrode may be different from the spacing between finger electrodes  111 C and the spacing between finger electrodes  111 P. 
     When finger electrodes  111 PR are disposed on the back surface, current collecting efficiency on the back surface increases, yet more light is prevented from entering through the back surface than light prevented from entering through the front surface. However, solar cell  11  according to the present embodiment is a mono-facial element whose light-receiving surface is the front surface. Thus, an increase in current collecting efficiency on the back surface has a greater influence than the influence of an increase in the amount of light prevented from entering through the back surface. Accordingly, solar cell  11  yields more advantageous effects of collecting current. 
     [2-2. Configuration of Collector Electrode According to Variation 1 of Embodiment 2] 
       FIG. 12  is a plan view and a cross-sectional view illustrating an electrode configuration of solar cell  11  according to Variation 1 of Embodiment 2. More specifically,  FIG. 12  shows an enlarged perspective plan view of the front surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 , and an enlarged cross-sectional view of a portion around the front surface of solar cell  11 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  illustrated in  FIG. 11 , only in the configurations of finger electrodes, connection electrodes, and a support electrode in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 11  while a description of the same points is omitted. 
     Bus bar electrode  112  is formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding member  40 A is disposed in both edge area Ap and central area Ac. Specifically, a bonding length in the longitudinal direction of tab line  20  along which bus bar electrode  112  and tab line  20  are bonded together is shorter than the length of electrically conductive bonding member  40 A in the longitudinal direction. Further, the length of bus bar electrode  112  in the longitudinal direction of tab line  20  is shorter than the length of electrically conductive bonding member  40 A in the longitudinal direction. Accordingly, even if solar cell  11  and tab line  20  repeatedly expand and contract due to temperature cycling, stress applied to tab line  20  between solar cells can be reduced. 
     Note that bus bar electrode  112  is formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in an edge area on a side opposite the edge area Ap. Even in this case, the same advantageous effects as those in the above are achieved. 
     As illustrated in the plan view in  FIG. 12 , finger electrodes  111 P 1  and  111 P 2  not directly connected with bus bar electrode  112 , connection electrode  113 B 1  which connects finger electrodes  111 P 1  and  111 P 2 , and connection electrode  113 B 2  which connects finger electrodes  111 P 1  and  111 P 2  to finger electrode  111 C are disposed in edge area Ap of solar cell  11 . Here, connection electrodes  113 B 1  and  113 B 2  are not in contact with electrically conductive bonding member  40 A. The arrangement of connection electrodes  113 B 1  and  113 B 2  allows electric charges from received light collected by finger electrodes  111 P 1  and  111 P 2  disposed in edge area Ap where bus bar electrode  112  is not disposed to be transferred to tab line  20  via finger electrodes  111 C and bus bar electrode  112 . Thus, current collecting efficiency can be improved. Connection electrodes  113 B 1  and  113 B 2  are not in contact with electrically conductive bonding member  40 A, and thus bonding strength between tab line  20  and solar cell  11  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     With regard to finger electrode  111 C to which connection electrode  113 B 2  is connected, the width of an electrode portion between bus bar electrode  112  and a connecting point with connection electrode  113 B 2  is greater than width W 111C  of other finger electrodes  111 C. The electrode portion transfers electric charges from received light collected by three finger electrodes, and thus a resistance loss is high if the electrode portion has normal width W 111C . To address this, the electrode portion has a width greater than width W 111C , and thus current collecting efficiency in and in the vicinity of edge area Ap can be improved. 
     Furthermore, width W 113B2  of connection electrode  113 B 2  is greater than width W 113B1  of connection electrode  113 B 1 . In other words, in edge area Ap, the width of the connection electrode closer to central area Ac is greater than the width of the connection electrode farther from central area Ac. Current collecting efficiency in and in the vicinity of edge area Ap is further improved by making the width of connection electrode  113 B 2 , which transfers electric charges from received light collected by two finger electrodes  111 P 1  and  111 P 2 , greater than the width of connection electrode  113 B 1  which transfers electric charges from received light collected by single finger electrode  111 P 1 . 
     As illustrated in the plan view in  FIG. 12 , in edge area Ap of solar cell  11 , support electrode  114 B which supports tab line  20  is formed in the outermost portion where electrically conductive bonding member  40 A is not disposed in the longitudinal direction of tab line  20 . Here, as illustrated in the cross-sectional view in  FIG. 12 , the thickness (height) of support electrode  114 B may be greater than the thickness of electrically conductive bonding member  40 A. Accordingly, as illustrated in the cross-sectional view in  FIG. 12 , a space is present between electrically conductive bonding member  40 A and tab line  20  in edge area Ap, and thus electrically conductive bonding member  40 A and tab line  20  are prevented from being in contact. Thus, deterioration of the shape of tab line  20  in the edge portion of solar cell  11  can be prevented. 
     Furthermore, as illustrated in the plan view in  FIG. 12 , support electrode  114 B is electrically connected with connection electrodes  113 B 1 . Accordingly, electric charges collected by outermost finger electrode  111 P 1  can be transferred to tab line  20  via support electrode  114 B and another connection electrode  113 B 1  disposed across tab line  20  from finger electrode  111 P 1 . Accordingly, for example, a connection electrode formed in area Ap 1  on a lower side of tab line  20  can be omitted. Thus, the flexibility of the electrode layout design improves while the current collecting efficiency in and in the vicinity of edge area Ap can be further improved. 
     [2-3. Configuration of Collector Electrode According to Variation 2 of Embodiment 2] 
       FIG. 13  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 2 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 13  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  illustrated in  FIG. 11 , only in the configurations of finger electrodes, connection electrodes, and support electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 11  while a description of the same points is omitted. 
     Bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A and  40 B are disposed in both edge area Ap and central area Ac. In other words, the bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in the edge area on a side opposite the edge area Ap. Even in this case, the same advantageous effects as those in the above can be achieved. 
     As illustrated in  FIG. 13 , finger electrodes  111 P not directly connected with bus bar electrodes  112  and connection electrodes  113 C which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . Here, connection electrodes  113 C are not in contact with electrically conductive bonding members  40 A and  40 B, and covered with tab lines  20  in the plan views. The arrangement of connection electrodes  113 C allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. In addition, connection electrodes  113 C are covered with tab lines  20  in the plan views, and thus less light is prevented from entering due to the connection electrodes, and current collecting efficiency can be further improved. Connection electrodes  113 C are not in contact with electrically conductive bonding members  40 A and  40 B, and thus the bonding strength between tab lines  20  and solar cell  11  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     With regard to finger electrodes  111 C to which connection electrodes  113 C are connected, the widths of electrode portions between bus bar electrodes  112  and connecting points with connection electrodes  113 C are greater than the width of other finger electrodes  111 C. The electrode portions transfers electric charges from received light collected by two or more finger electrodes, and thus resistance of collecting current will be high if the electrode portions have a normal width. To address this, the electrode portions have widths greater than the normal width, and thus the current collecting efficiency in and in the vicinity of edge area Ap can be improved. 
     Note that although not illustrated in  FIG. 13 , support electrodes which support tab lines  20  may be disposed in edge area Ap in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab line  20 . Furthermore, the support electrodes may be electrically connected with connection electrodes  113 C. 
     [2-4. Configuration of Collector Electrode According to Variation 3 of Embodiment 2] 
       FIG. 14  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 3 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 14  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 13 , only in the configuration of connection electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 13  while a description of the same points is omitted. 
     Bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A and  40 B are disposed in both edge area Ap and central area Ac. Specifically, the bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in an edge area on a side opposite edge area Ap. Even in this case, the same advantageous effects as those in the above can be achieved. 
     As illustrated in  FIG. 14 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , connection electrodes  113 D which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 D allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     Connection electrodes  113 D are in contact with electrically conductive bonding members  40 A and  40 B in edge area Ap on a side closer to central area Ac, and are not in contact with electrically conductive bonding members  40 A and  40 B in edge area Ap on a side farther from central area Ac. Stated differently, connection electrodes  113 D each have, in edge area Ap, a portion separate from electrically conductive bonding member  40 A/ 40 B. Accordingly, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     Connection electrodes  113 D are covered with tab lines  20  in the plan views. Accordingly, less light is prevented from entering due to connection electrodes  113 D, and light collecting efficiency can be further improved. 
     Note that although not illustrated in  FIG. 14 , support electrodes which support tab lines  20  may be disposed in edge area Ap in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab lines  20 . The support electrodes may be electrically connected with connection electrodes  113 D. 
     [2-5. Configuration of Collector Electrode According to Variation 4 of Embodiment 2] 
       FIG. 15  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 4 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 15  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 13  only in the configuration of connection electrodes and support electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 13  while a description of the same points is omitted. 
     Bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A and  40 B are disposed in both edge area Ap and central area Ac. In other words, bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in the edge area on a side opposite edge area Ap. Even in this case, the same advantageous effects as in the above can be achieved. 
     As illustrated in  FIG. 15 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , and connection electrodes  113 E which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 E allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     In the plan views, connection electrodes  113 E are formed into zigzags relative to the longitudinal direction of tab lines  20  between finger electrodes  111 C and  111 P, and discretely covered with tab lines  20 . Accordingly, less light is prevented from entering due to connection electrodes  113 E, and light collecting efficiency can be further improved. 
     Connection electrodes  113 E are not in contact with electrically conductive bonding members  40 A and  40 B. Accordingly, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     In edge area Ap, support electrodes  114 E which support tab lines  20  are formed in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab line  20 . Here, the thickness (height) of support electrodes  114 E may be greater than the thickness of electrically conductive bonding members  40 A and  40 B. This provides, in edge area Ap, a space between tab line  20  and electrically conductive bonding member  40 A, and a space between tab line  20  and electrically conductive bonding member  40 B. Accordingly, electrically conductive bonding members  40 A and  40 B are prevented from being in contact with tab lines  20 . Thus, deterioration of the shape of tab lines  20  in the edge portion of solar cell  11  can be prevented. 
     Note that support electrodes  114 E may be electrically connected with connection electrodes  113 E. Accordingly, for example, electric charges collected by outermost finger electrode  111 P on the back surface can be transferred to tab line  20  via support electrode  114 E and connection electrode  113 E disposed across tab line  20  from outermost finger electrode  111 P. Accordingly, for example, in edge area Ap on the back surface, a portion of connection electrode  113 E directly connected with outermost finger electrode  111 P can be omitted. Thus, the current collecting efficiency in and in the vicinity of edge area Ap can be further improved, and also flexibility in designing the electrode layout improves. 
     [2-6. Configuration of Collector Electrode According to Variation 5 of Embodiment 2] 
       FIG. 16  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 5 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 16  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 13  only in the configuration of connection electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 13  while a description of the same points is omitted. 
     Bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A and  40 B are disposed in both edge area Ap and central area Ac. Thus, the bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in an edge area located on a side opposite edge area Ap. Even in this case, the same advantageous effects as those in the above are achieved. 
     As illustrated in  FIG. 16 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , and connection electrodes  113 F which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 F allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     In the plan views, connection electrodes  113 F are formed into zigzags between finger electrodes  111 C and  111 P relative to the longitudinal direction of tab lines  20 , and are discretely covered with tab lines  20 . Accordingly, less light is prevented from entering due to connection electrodes  113 F, and light collecting efficiency can be further improved. 
     Connection electrodes  113 F are discretely in contact with electrically conductive bonding members  40 A and  40 B. Accordingly, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     Note that although not illustrated in  FIG. 16 , support electrodes which support tab lines  20  may be disposed in edge area Ap in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab line  20 . The support electrodes may be electrically connected with connection electrodes  113 F. 
     [2-7. Configuration of Collector Electrode According to Variation 6 of Embodiment 2] 
       FIG. 17  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 6 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 17  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 13  in the configuration of connection electrodes in edge area Ap and in that dummy electrodes are disposed in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 13  while a description of the same points is omitted. 
     Bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac. In contrast, electrically conductive bonding members  40 A and  40 B are disposed in both edge area Ap and central area Ac. Thus, bonding lengths in the longitudinal direction of tab lines  20  along which tab lines  20  and bus bar electrodes  112  are bonded together are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. The lengths of bus bar electrodes  112  in the longitudinal direction of tab lines  20  are shorter than the lengths of electrically conductive bonding members  40 A and  40 B in the longitudinal direction. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that bus bar electrodes  112  are formed only in central area Ac among edge area Ap and central area Ac, but may also be formed in an edge area on a side opposite edge area Ap. Even in this case, the same advantageous effects as those in the above are achieved. 
     As illustrated in  FIG. 17 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , and connection electrodes  113 G which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 G allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     Connection electrodes  113 G are not in contact with electrically conductive bonding members  40 A and  40 B, and are not covered with tab lines  20  in the plan views. Furthermore, solar cell  11  according to this variation includes dummy electrodes  114 G 1  in edge area Ap. Here, the surface area occupancy in the plan views of dummy electrodes  114 G 1  relative to electrically conductive bonding members  40 A and  40 B in edge area Ap is lower than the surface area occupancy in the plan views of bus bar electrodes  112  relative to electrically conductive bonding members  40 A and  40 B in central area Ac. In order to achieve this relation, for example, the widths of dummy electrodes  114 G 1  are narrower than the widths of bus bar electrodes  112 . The arrangement of dummy electrodes  114 G 1  allows tab lines  20  in edge area Ap to be bonded onto solar cell  11  only on dummy electrodes  114 G 1 . Thus, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that dummy electrode  11401  may extend parallel to the direction in which tab line  20  is formed (on the front surface in  FIG. 17 ), or may be formed inclined to the direction in which tab line  20  is formed (on the back surface in  FIG. 17 ). 
     Note that although not illustrated in  FIG. 17 , support electrodes which support tab lines  20  may be disposed in edge area Ap in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab line  20 . The support electrodes may be electrically connected with connection electrodes  113 G. 
     [2-8. Configuration of Collector Electrode According to Variation 7 of Embodiment 2] 
       FIG. 18  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 7 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 18  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 6 illustrated in  FIG. 17  only in the configuration of dummy electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 17  while a description of the same points is omitted. 
     Solar cell  11  according to this variation includes dummy electrodes  114 G 2  in edge area Ap. Here, the surface area occupancy in the plan views of dummy electrodes  114 G 2  relative to electrically conductive bonding members  40 A and  40 B in edge area Ap is lower than the surface area occupancy in the plan views of bus bar electrodes  112  relative to electrically conductive bonding members  40 A and  40 B in central area Ac. In order to achieve this relation, for example, the widths of dummy electrodes  114 G 2  are narrower than the widths of bus bar electrodes  112 . Furthermore, dummy electrodes  114 G 2  are discretely disposed in edge area Ap, and discretely bonded by electrically conductive bonding members  40 A and  40 B. The arrangement of dummy electrodes  114 G 2  allows tab lines  20  to be bonded onto solar cell  11  in edge area Ap only on dummy electrodes  114 G 2 . Thus, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. Accordingly, even if solar cell  11  and tab lines  20  repeatedly expand and contract due to temperature cycling, stress applied to tab lines  20  between solar cells can be reduced. 
     Note that dummy electrodes  114 G 2  may extend parallel to the direction in which tab lines  20  are formed, or may be formed inclined relative to the direction in which tab lines  20  are formed. 
     [2-9. Configuration of Collector Electrode According to Variation 8 of Embodiment 2] 
       FIG. 19  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 8 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 19  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 13  in the configuration of connection electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 13  while a description of the same points is omitted. 
     As illustrated in  FIG. 19 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , and connection electrodes  113 H which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 H allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     Connection electrodes  113 H are disposed in the outer edge areas of the flat areas of the solar cell. Specifically, connection electrodes  113 H are formed in inactive areas that do not have a light collecting function. This prevents an increase in the amount of light prevented from entering due to the arrangement of connection electrodes  113 H. 
     Connection electrodes  113 H are not in contact with electrically conductive bonding members  40 A and  40 B, and are not covered with tab lines  20  in the plan views. Accordingly, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     Note that although not illustrated in  FIG. 19 , support electrodes which support tab lines  20  may be disposed in edge area Ap in the outermost portions where electrically conductive bonding members  40 A and  40 B are not disposed in the longitudinal direction of tab lines  20 . 
     The widths of finger electrodes  111 C connected with connection electrodes  113 H may be the greatest among the widths of other finger electrodes  111 C. Finger electrodes  111 C connected with connection electrodes  113 H transfer electric charges from received light collected by finger electrodes  111 P, in addition to electric charges from received light collected by finger electrodes  111 C connected with connection electrodes  113 H, and thus resistance loss will be greater if the finger electrodes have the normal width. To address this, if the widths of finger electrodes  111 C connected with connection electrodes  113 H are made greater, the current collecting efficiency in and in the vicinity of edge area Ap can be improved. 
     Furthermore, the widths of connection electrodes  113 H may be increased toward central area Ac. For example, if on the back surface, the width of a portion of connection electrode  113 H closer to central area Ac which transfers electric charges from received light collected by two finger electrodes  111 P is made greater than the width of a portion of connection electrode  113 H farther from central area Ac, which transfers electric charges from received light collected by one finger electrode  111 P, current collecting efficiency in and in the vicinity of edge area Ap can be further improved. 
     [2-10. Configuration of Collector Electrode According to Variation 9 of Embodiment 2] 
       FIG. 20  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 9 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 20  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 8 illustrated in  FIG. 19  in the configuration of a connection electrode in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 19  while a description of the same points is omitted. 
     As illustrated in  FIG. 20 , finger electrodes  111 P not directly connected with bus bar electrodes  112 , and connection electrodes  113 J which connect finger electrodes  111 P to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . The arrangement of connection electrodes  113 J allows electric charges from received light collected by finger electrodes  111 P disposed in edge area Ap where bus bar electrodes  112  are not disposed to be transferred to tab lines  20  via finger electrodes  111 C and bus bar electrodes  112 . Thus, current collecting efficiency can be improved. 
     Connection electrodes  113 J are not in contact with electrically conductive bonding members  40 A and  40 B, and are not covered with tab lines  20  in the plan views. Accordingly, the bonding strength between solar cell  11  and tab lines  20  in edge area Ap can be securely made lower than the bonding strength in central area Ac. 
     Connection electrodes  113 J are disposed in active areas having a light collecting function, and disposed close to tab lines  20 , within flat areas of a solar cell. Accordingly, as compared with connection electrodes  113 H illustrated in  FIG. 19 , more light is prevented from entering due to the arrangement of connection electrodes  113 J, yet the resistance loss caused when transferring electric charges from received light to bus bar electrodes  112  can be reduced. 
     The widths of finger electrodes  111 C connected with connection electrodes  113 J may be the greatest among the widths of other finger electrodes  111 C. Finger electrodes  111 C connected with connection electrodes  113 J also transfer electric charges from received light collected by finger electrodes  111 P, in addition to the electric charges from received light collected by finger electrodes  111 C connected with connection electrodes  113 J, and thus resistance loss increases if the finger electrodes have a normal electrode width. To address this, current collecting efficiency in and in the vicinity of edge area Ap can be improved by giving great widths to finger electrodes  111 C connected with connection electrodes  113 J. 
     Furthermore, the widths of connection electrodes  113 J may be increased toward central area Ac. For example, if on the back surface, the width of a portion of connection electrode  113 J closer to central area Ac, which transfers electric charges from received light collected by two finger electrodes  111 P, is made greater than the width of a portion of connection electrode  113 J farther from central area Ac, which transfers electric charges from received light collected by single finger electrode  111 P, current collecting efficiency in and in the vicinity of edge area Ap can be further improved. 
     [2-11. Configuration of Collector Electrode According to Variation 10 of Embodiment 2] 
       FIG. 21  shows plan views illustrating an electrode configuration of solar cell  11  according to Variation 10 of Embodiment 2 on a front surface side and a back surface side. More specifically,  FIG. 21  shows enlarged perspective plan views of the front surface and the back surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 8 illustrated in  FIG. 19  in the configuration of finger electrodes and connection electrodes in edge area Ap. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 19  while a description of the same points is omitted. 
     As illustrated in  FIG. 21 , finger electrodes  111 K which are directly connected with finger electrodes  111 C disposed in central area Ac, and are not parallel to finger electrodes  111 C are disposed in edge area Ap of solar cell  11 . Since finger electrodes  111 C and finger electrodes  111 K are connected directly, connection electrodes are not disposed. 
     According to the arrangement of finger electrodes  111 K, the surface area of electrodes in an active area can be reduced as compared with the case where a connection electrode which connects finger electrodes is disposed, and thus less light is prevented from entering. Thus, light collecting efficiency can be improved. 
     [2-12. Configuration of Collector Electrode According to Variation 11 of Embodiment 2] 
       FIG. 22A  is a plan view illustrating an electrode configuration of solar cell  11  according to Variation 11 of Embodiment 2. More specifically,  FIG. 22A  shows an enlarged perspective plan view of the front surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 2 illustrated in  FIG. 11  in the spacing between finger electrodes as a configuration. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 11  while a description of the same points is omitted. 
     As illustrated in the plan view in  FIG. 22A , finger electrode  111 P connected with bus bar electrode  112  is disposed in edge area Ap of solar cell  11 . Here, with regard to the spacing between finger electrode  111 P which crosses the endmost portion of bus bar electrode  112  and finger electrode  111 C next to finger electrode  111 P, such spacing Gc in a first area farther from bus bar electrode  112  is greater than such spacing Gp in a second area closer to bus bar electrode  112  than the first area is. Accordingly, finger electrode  111 P can be disposed also in edge area Ap while the length of bus bar electrode  112  is shorter than the length of electrically conductive bonding member  40 A/ 40 B. 
     [2-13. Configuration of Collector Electrode According to Variation 12 of Embodiment 2] 
       FIG. 22B  is a plan view illustrating an electrode configuration of solar cell  11  according to Variation 12 of Embodiment 2. More specifically,  FIG. 22B  shows an enlarged perspective plan view of the front surface of solar cell  11  in the structural cross-sectional view in  FIG. 4 . The electrode configuration of solar cell  11  according to this variation is different from the electrode configuration of solar cell  11  according to Variation 11 illustrated in  FIG. 22A  in the spacing between finger electrodes. The following description focuses on differences from the electrode configuration of solar cell  11  illustrated in  FIG. 22A  while a description of the same points is omitted. 
     As illustrated in the plan view in  FIG. 22B , finger electrode  111 P connected with bus bar electrode  112  is disposed in edge area Ap of solar cell  11 . Here, in the plan view, spacing Gf between finger electrodes in a first area farther from bus bar electrode  112  is greater than spacing Gn between finger electrodes in a second area closer to bus bar electrode  112  than the first area is. Accordingly, finger electrode  111 P can be disposed also in edge area Ap while the length of bus bar electrode  112  is shorter than the length of electrically conductive bonding member  40 A/ 40 B. Thus, current collecting efficiency can be improved while reducing stress applied to tab line  20 . 
     Other Embodiments 
     The above completes description of the solar cell module to according to the present disclosure based on Embodiments 1 and 2 and the variations thereof, yet the present disclosure is not limited to Embodiments 1 and 2 and the variations thereof described above. 
     For example, in Embodiments 1 and 2 and the variations thereof described above, it is sufficient if solar cell  11  has a function of providing photovoltaic effects, and thus the structure of the solar cell is not limited to those as described above. 
     Embodiments 1 and 2 and the variations thereof described above have shown aspects in which both the front surface and the back surface of solar cell  11  have an electrode configuration having the features as described above, yet one of the surfaces of solar cell  11  may have the electrode configuration having the above features. 
     Specifically, a solar cell module includes: two solar cells  11  adjacent to each other in a direction parallel to a light-receiving surface of the solar cell module; tab line  20  which is disposed on a front surface of a first solar cell among two solar cells  11  and a back surface of a second solar cell among two solar cells  11 , and electrically connects two solar cells  11 ; and electrically conductive bonding members  40 A and  40 B which bond tab line  20  to two solar cells  11 , wherein bonding strength between tab line  20  and at least one of two solar cells  11  in edge area Ap is lower than bonding strength between tab line  20  and the at least one of two solar cells  11  in central area Ac. Accordingly, even if solar cell  11  and tab line  20  repeatedly expand and contract due to temperature cycling, stress applied to tab line  20  between solar cells can be reduced. 
     Furthermore, the bus bar electrodes, the finger electrodes, and the connection electrodes may be formed into curves, rather than straight lines. A connecting portion between a finger electrode and a connection electrode may be roundish in a plan view. 
     Although the solar cell module according to the above embodiments has a configuration in which solar cells  11  are disposed in a matrix on a plane, but solar cells  11  may not be disposed in a matrix. For example, solar cells  11  may be disposed in a circle or a one-dimensionally straight or curved line. 
     The scope of the present disclosure may also include embodiments as a result of adding various modifications, which may be conceived by those skilled in the art, to Embodiments 1 and 2 and the variations thereof described above, and embodiments obtained by combining elements and functions in Embodiments 1 and 2 and the variations thereof in any manner as long as the combination does not depart from the spirit of the present disclosure. 
     While the foregoing has described one or more embodiments and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present teachings.