Patent Publication Number: US-2015068596-A1

Title: Solar cell module and method for manufacturing solar cell module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation under 35 U.S.C. §120 of PCT/JP2012/066667, filed Jun. 29, 2012, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a solar cell module in which solar cells are connected by wiring material, and a method for manufacturing the solar cell module. 
     BACKGROUND ART 
     In addition to a vapor deposition method, a sputtering method, and screen printing that prints a conductive paste, a plating method is also used as a method for forming electrodes of a solar cell. 
     For example, in Patent Literature 1, as a method for manufacturing a solar cell, a method is described in which seed metal is disposed on a silicon substrate, and the seed metal is used to form a surface electrode and a rear electrode by electrolytic plating. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1 
     
         
         Japanese Patent Laid-Open Publication No. 2000-294819 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     An object of the present invention is to provide a solar cell module with superior performance. 
     Solution to Problem 
     A solar cell module according to the present invention includes: a photoelectric conversion section; a collecting electrode disposed on the photoelectric conversion section; an adhesive layer disposed on the collecting electrode; and wiring material that is connected to the collecting electrode with the adhesive layer therebetween; wherein: in the collecting electrode, a thickness of an end portion of the collecting electrode is formed thicker than a center portion thereof in a longitudinal direction of the collecting electrode; and in the adhesive layer, a thickness of a portion corresponding to the center portion of the collecting electrode is formed thicker than a thickness of a portion corresponding to the end portion of the collecting electrode in the longitudinal direction of the collecting electrode. 
     A method for manufacturing a solar cell module according to the present invention is a method that forms a collecting electrode on a photoelectric conversion section, and connects wiring material to the collecting electrode with an adhesive layer therebetween, wherein: a power supply section is provided at both end portions of the photoelectric conversion section in a longitudinal direction of the collecting electrode, and the collecting electrode is formed by electrolytic plating in a formation region for the collecting electrode on the photoelectric conversion section; an adhesive is coated on the collecting electrode to form an adhesive layer; the collecting electrode and the wiring material are connected by pressing the wiring material from above the adhesive layer; a thickness of an end portion of the collecting electrode is formed thicker than a thickness of a center portion thereof in the longitudinal direction of the collecting electrode by electrolytic plating; and in the adhesive layer, a thickness of a portion that corresponds to the center portion of the collecting electrode is formed thicker than a thickness of a portion thereof that corresponds to the end portion of the collecting electrode in the longitudinal direction of the collecting electrode by pressing the wiring material against the collecting electrode. 
     Advantageous Effects of Invention 
     The present invention provides a solar cell module with superior performance by means of the above described configuration. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1(   a ) and ( b ) are a plan view and a sectional view of a solar cell module of an embodiment according to the present invention. 
         FIG. 2  is a flowchart showing procedures of a method for manufacturing a solar cell module of the embodiment according to the present invention. 
         FIGS. 3(   a ) and ( b ) are views illustrating a substrate with a plating mask in a procedure described in  FIG. 2 . 
         FIG. 4  is a view illustrating electrolytic plating that is performed next after the procedure illustrated in  FIGS. 3(   a ) and ( b ). 
         FIG. 5  is a view illustrating a solar cell having a collecting electrode that is formed by the electrolytic plating illustrated in  FIG. 4 . 
         FIG. 6   FIG. 6  is a view illustrating adhesive layers and wiring materials that are prepared next after the procedure illustrated in  FIG. 5 . 
         FIG. 7  is a view illustrating a process that crimps the wiring materials through the adhesive layers onto a solar cell having collecting electrodes. 
         FIG. 8  is a view illustrating a solar cell module that is formed by the crimping process illustrated in  FIG. 7 . 
         FIGS. 9(   a ) and ( b   1 ) to ( b   3 ) are a plan view and sectional views of a solar cell formed by performing electrolytic plating using a plating mask in the embodiment according to the present invention. 
         FIG. 10   FIG. 10  is a flowchart showing procedures of a plating process in the embodiment according to the present invention. 
         FIG. 11  illustrates a textured substrate in a procedure described in  FIG. 10 . 
         FIG. 12   FIG. 12  is a view illustrating a matte plated layer that is formed next after the procedure illustrated in  FIG. 11 . 
         FIG. 13  is a view illustrating a bright plated layer that is formed next after the procedure illustrated in  FIG. 12 . 
         FIG. 14  is a view illustrating an action of a solar cell module that uses the solar cell formed by the process described in  FIG. 10 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereunder, an embodiment of the present invention is described in detail using the accompanying drawing. In the following description, like constituent elements are denoted by like reference numerals in all of the drawings, and duplicated descriptions are omitted. Further, in the description in the text, previously mentioned reference numerals are used where necessary. 
       FIGS. 1(   a ) and ( b ) illustrate a solar cell module  10 , in which (a) is a plan view and (b) is a sectional view. The solar cell module  10  includes a photoelectric conversion section  11 , collecting electrodes  12  and  13  that are formed on both sides of the photoelectric conversion section  11 , wiring material  15  that is connected to the collecting electrode  12  with an adhesive layer  14  therebetween, and wiring material  17  that is connected to the collecting electrode  13  with an adhesive layer  16  therebetween. 
     The photoelectric conversion section  11  includes, as main surfaces, a light-receiving surface that is a face on which light from outside is incident, and a rear surface that is a face on the opposite side to the light-receiving surface. In  FIG. 1(   b ), the collecting electrode  12  side is the light-receiving surface, and the collecting electrode  13  side is the rear surface. Although the light-receiving surface and the rear surface are illustrated as having the same structure in  FIG. 1(   b ), there may be a difference in sectional views between the light-receiving surface and the rear surface depending on the specifications of the photoelectric conversion section  11 . 
     The photoelectric conversion section  11  generates photogenerated carriers that are electron-hole pairs by receiving light such as the light of the sun. The photoelectric conversion section  11 , for example, has a substrate made of a semiconductor material such as crystalline silicon (c-Si), gallium arsenide (GaAs), or indium phosphide (InP). The structure of the photoelectric conversion section  11  is a p-n junction in a broad sense. For example, a heterojunction between an n-type single-crystal silicon substrate and amorphous silicon can be used. In such a case, a structure can be adopted in which an i-type amorphous silicon layer, a p-type amorphous silicon layer doped with boron (B) or the like, and a transparent conductive film (TCO) made of a translucent conductive oxide such as indium oxide (In 2 O 3 ) are laminated on a light-receiving surface side of the substrate, while an i-type amorphous silicon layer, an n-type amorphous silicon layer doped with phosphorus (P) or the like, and a transparent conductive film are laminated on a rear surface side of the substrate. 
     As long as the photoelectric conversion section  11  has a function that converts light such as sunlight to electricity, a structure other than the structure described above may also be adopted. For example, a structure may be adopted that includes a p-type polycrystalline silicon substrate, an n-type diffusion layer that is formed on the light-receiving surface side thereof, and an aluminum metal film that is formed on the rear surface side thereof. 
     The collecting electrodes  12  and  13  are electrode layers that are formed by a plating method on the light-receiving surface and the rear surface of the photoelectric conversion section  11 , respectively, and are electrically connected to the photoelectric conversion section  11 . Because the collecting electrodes  12  and  13  are formed by a plating method, the thickness of the collecting electrodes  12  and  13  at end portions in an X direction of the photoelectric conversion section  11  is thicker than the thickness of the collecting electrodes  12  and  13  at the center portion of the photoelectric conversion section  11 . In this case, as shown in  FIGS. 1(   a ) and ( b ), the X direction is a longitudinal direction in which the collecting electrodes  12  and  13  extend. In  FIG. 1(   b ), in the X direction, the thickness of the collecting electrodes  12  and  13  is shown as being thicker at end portions A and B of the light-receiving surface on the photoelectric conversion section  11  and at end portions C and D of the rear surface. Note that in this case, a difference between the thicknesses of the end portions and the center portions of the collecting electrodes  12  and  13  is shown in an exaggerated form. The term “end portions of the collecting electrodes  12  and  13  in the X direction” includes the vicinity of peripheral edge portions of the photoelectric conversion section  11 , and not only ends on the photoelectric conversion section  11  in the X direction in a strict sense. 
     The wiring material  15  on the light-receiving surface side is a conductive material that is pressed against the photoelectric conversion section  11  through the adhesive layer  14  to be mechanically and electrically connected to the collecting electrode  12 . 
     The wiring material  15  is a thin plate that is composed of a metal conductive material such as copper. Wiring material having a twisted-wire shape can also be used instead of a thin plate. Besides copper, it is also possible to use silver, aluminum, nickel, tin, gold or alloys of these metals as the conductive material. Note that although in  FIG. 1(   b ) an end face of the wiring material  15  and an end face of the collecting electrode  12  are aligned, this is an illustration of one example, and naturally the wiring material  15  can be set so as to be longer than the collecting electrode  12  to a certain extent. 
     The adhesive layer  14  is arranged between the collecting electrode  12  and the wiring material  15 , and is a layer of resin adhesive that mechanically and electrically connects the collecting electrode  12  and the wiring material  17  as a result of crimping. The adhesive layer  14  is preferably an elastic and contractile material. A thermosetting resin adhesive layer that is acryl-based, highly flexible polyurethane-based, or epoxy-based can be used as the adhesive layer  14 . The resin adhesive layer may be a liquefied layer or may be a resin adhesive sheet in a semi-cured state. Hereunder, the description is continued on the assumption that a resin adhesive sheet is used as the adhesive layer  14 . 
     Preferably, conductive particles are included in the adhesive layer  14 . In such a case, nickel, silver, gold-coated nickel, tin-plated copper and the like can be used as the conductive particles. When using an insulating resin adhesive layer that does not include conductive particles, a configuration is adopted in which either one of, or both of, the mutually opposing faces of the wiring material  15  and the collecting electrode  12  are rendered uneven, and the insulating resin is appropriately removed from between the wiring material  15  and the collecting electrode  12  to electrically connect the wiring material  15  and the collecting electrode  12 . 
     Although originally the adhesive layer  14  has an even thickness, the thickness thereof at the end portions of the photoelectric conversion section  11  and the thickness at the center portion become uneven during the process in which the wiring material  15  is pressed against the photoelectric conversion section  11 . That is, since the thickness of the collecting electrode  12  is thick at the end portions A and B of the photoelectric conversion section  11  and the thickness of the collecting electrode  12  is thin at the center portion of the photoelectric conversion section  11 , when the wiring material  15  is pressed through the adhesive layer  14 , a pressing force with respect to the adhesive layer  14  is liable to rise at the end portions A and B at which the collecting electrode  12  projects more, in comparison to the center portion. Consequently, the adhesive layer  14  is more liable to be removed at the end portions A and B of the collecting electrode  12  than at the center portion, and the thickness thereof becomes thinner at the end portions A and B and becomes thicker at the center portion. 
     Similarly, the wiring material  17  on the rear surface side is a conductive material that is pressed against the photoelectric conversion section  11  through the adhesive layer  16  to be mechanically and electrically connected to the collecting electrode  13 . The material of the wiring material  17  is the same as that of the wiring material  15 . The material of the adhesive layer  16  is the same as that of the adhesive layer  14 . On the rear surface also, similarly to the light-receiving surface side, the thickness of the adhesive layer  16  is thinner at the end portions C and D and thicker at the center portion. 
     Thus, in the X direction, the thickness of the respective adhesive layers  14  and  16  is thinner at portions corresponding to the end portions A, B, C and D at which the thickness of the collecting electrodes  12  and  13  is thick, and the thickness of the respective adhesive layers  14  and  16  is thicker at a portion corresponding to the center portion at which the thickness of the collecting electrodes  12  and  13  is thin. Therefore, a structure can be formed in which mechanical joints between the wiring materials  15  and  17  and the collecting electrodes  12  and  13  are strong and the electrical resistance is low at the end portions on the photoelectric conversion section  11  at which current crowding is liable to arise in the wiring materials  15  and  17 . The reason that current crowding is liable to arise at the portions of the wiring materials  15  and  17  that are at the end portions of the photoelectric conversion section  11  is as follows. Although currents that flow through the wiring materials  15  and  17  separate in all directions at the center portion of the photoelectric conversion section  11 , a state is entered in which all the currents are gathered at the end portions of the photoelectric conversion section  11 . Consequently, the current density is high at the portions of the wiring materials  15  and  17  at the end portions of the photoelectric conversion section  11  and current crowding occurs. 
       FIG. 2  is a flowchart showing procedures of a method for manufacturing the solar cell module  10  having the above described configuration.  FIG. 3  to  FIG. 8  are views that illustrate the manner of the procedures described in  FIG. 2 . 
     First, the photoelectric conversion section  11  that has a substrate is prepared (S 10 ). Next, a plating mask is disposed on the photoelectric conversion section  11  to prepare for the subsequent electrolytic plating.  FIGS. 3(   a ) and ( b ) illustrate a substrate with a plating mask  20 , in which (a) is a plan view and (b) is a side view. The side view in  FIG. 3(   b ) is a view along a line E-E in the plan view in  FIG. 3(   a ). 
     In this case, a resist having opening sections  22 ,  23  and  24  for forming a collecting electrode is provided as a plating mask  21  on the photoelectric conversion section  11 . The opening sections  22  to  24  are provided on each of the light-receiving surface side and the rear surface side of the photoelectric conversion section  11 . Although the opening sections  22  to  24  have a rectangular shape, naturally the opening sections  22  to  24  may also have a shape other than a rectangular shape. The number of opening sections may also be other than three. Although the shape of the opening sections  22  to  24  on the light-receiving surface side and the shape of the opening sections on the rear surface are the same, naturally the shapes and numbers of the opening sections on the respective sides may be different to each other. 
     To form the plating mask  21  on the photoelectric conversion section  11 , a method can be used in which a photosensitive resist is coated on the photoelectric conversion section  11 , and the resist at the portions for the opening sections  22  to  24  is removed by performing selective exposure and development. Besides the aforementioned method, a method may also be adopted in which a mask layer having the opening sections  22  to  24  is printed on the photoelectric conversion section  11  by screen printing. Thus, the substrate with a plating mask  20  is obtained. 
     Returning again to  FIG. 2 , next, collecting electrodes are formed by electrolytic plating using the substrate with a plating mask  20  (S 11 ).  FIG. 4  is a view illustrating the manner in which the electrolytic plating is performed. The electrolytic plating is performed by the following procedure. 
     Power supply terminals for plating  25 ,  26 ,  27  and  28  are connected to the substrate with a plating mask  20 . The power supply terminals  25  and  28  are also connected to the rear surface side, and not only to the light-receiving surface side. 
     Although omitted from the illustration in  FIGS. 3(   a ) and ( b ), open holes for connecting the power supply terminals  25  to  28  to the substrate with a plating mask  20  are provided near the end portions in the X direction of the photoelectric conversion section  11  in the plating mask  21 . Since the formation regions of the collecting electrode  12  are the opening sections  22  to  24 , the power supply terminals  25  to  28  are connected at positions that are further to the end portion side than the opening sections  22  to  24 . Thus, the power supply terminals  25  to  28  are electrically connected to the photoelectric conversion section using the open holes with respect to which the plating mask  21  of the substrate with a plating mask  20  is not applied. Note that a configuration may also be adopted in which a seed metal layer is provided for plating, and the power supply terminals  25  to  28  are electrically connected to the seed metal layer. 
     The power supply terminals  25  to  28  are connected to the light-receiving surface side and the rear surface side, respectively, of the substrate with a plating mask  20 , and a predetermined plating solution  31  is filled in a plating bath  30 . Cyanide-based and non-cyanide-based solutions containing ions of the plating metal are available as the predetermined plating solution  31 , and a non-cyanide-based solution is preferable from a safety aspect. The non-cyanide-based solution may be any of a non-cyanide-based neutral type, a non-cyanide-based weak acidic type, a non-cyanide-based acidic type, a non-cyanide-based weak alkaline type, and a non-cyanide-based alkaline type. Gold, silver, copper, nickel, palladium, platinum or the like may be used as the plating metal. In the case of copper plating, copper sulfate, copper pyrophosphate, copper cyanide or the like is used, while in the case of nickel plating, nickel chloride, Watt&#39;s nickel, nickel sulfamate or the like is used. 
     Further, anode plates  32  and  33  made of the same material as the plating metal are prepared. The anode plates  32  and  33  are for plating the light-receiving surface side and plating the rear surface side of the substrate with a plating mask  20 , respectively. Lead lines are connected from each of the power supply terminals  25  to  28  on the light-receiving surface side of the substrate with a plating mask  20 , and the four leader lines are put together to form a single cathode terminal on the light-receiving surface side. A leader line is also connected to an end portion of the anode plate  32  to form an anode terminal on the light-receiving surface side. Similarly, although not illustrated in  FIG. 4 , a leader line is connected from each of the four power supply terminals on the rear surface side of the substrate with a plating mask  20 , and the four leader lines are put together to form a single cathode terminal on the rear surface side. A leader line is also connected to an end portion of the anode plate  33  to form an anode terminal on the rear surface side. 
     The anode plate  32  connected to the anode terminal on the light-receiving surface side, the anode plate  33  connected to the anode terminal on the rear surface side, and the substrate with a plating mask  20  connected to the cathode terminal on the light-receiving surface side and the cathode terminal on the rear surface side are immersed in the plating solution  31 . With respect to the arrangement of the anode plates  32  and  33  and the substrate with a plating mask  20 , as shown in  FIG. 4 , a substrate with a plating mask  20  is arranged between the anode plates  32  and  33  so that the light-receiving surface of the substrate with a plating mask  20  faces the anode plate  32 , and the rear surface of the substrate with a plating mask  20  faces the anode plate  33 . The clearance between the anode plate  32  and the light-receiving surface of the substrate with a plating mask  20  is set to be the same as a clearance between the anode plate  33  and the rear surface of the substrate with a plating mask  20 . These clearances are one of the plating conditions, and can be set to optimal value by experimentation or the like. 
     A plating power source  34  for the light-receiving surface side is connected between the anode terminal and cathode terminal on the light-receiving surface side, and a plating power source  35  for the rear surface side is connected between the anode terminal and cathode terminal on the rear surface side. Ions of the plating metal contained in the plating solution  31  move when a current is made to flow between the anode terminal and cathode terminal on the light-receiving surface side from the plating power source  34 , and the plating metal deposits on the opening sections  22  to  24  on the light-receiving surface side of the substrate with a plating mask  20 . Similarly, ions of the plating metal contained in the plating solution  31  move when a current is made to flow between the anode terminal and cathode terminal on the rear surface side from the plating power source  35 , and the plating metal deposits on the opening sections  22  to  24  on the rear surface side of the substrate with a plating mask  20 . Thus, electrolytic plating with respect to the substrate with a plating mask  20  is performed. 
     The thickness of a metal layer that deposits is the plating thickness. The plating thickness is determined by the size of a charge amount per unit area in the plating process. Since a charge amount is represented by (current value×time), if the period of time is the same, the plating thickness increases as the current value increases. According to the present embodiment, the conditions for the electrolytic plating, such as the positions of the power supply terminals  25  to  28  and the charge amount and the like, are set so that the plating thickness of the collecting electrodes  12  and  13  is thicker at the end portions than at the center portion in the X direction of the photoelectric conversion section  11 . 
     After predetermined electrolytic plating has been performed with respect to the substrate with a plating mask  20 , operation of the plating power sources  34  and  35  is stopped. The substrate with a plating mask  20  with respect to which the electrolytic plating was performed is then lifted up from the plating solution  31 , and after being suitably washed, the power supply terminals  25  to  28  on the light-receiving surface side and the power supply terminals on the rear surface side are detached. The plating mask  21  is then removed. An applicable solvent can be used to remove the plating mask  21 . 
       FIG. 5  is a view that illustrates a solar cell  40  from which a plating mask was removed and in which the collecting electrodes  12  and  13  were formed by electrolytic plating on the photoelectric conversion section  11 .  FIG. 5  corresponds to a sectional view along a line E-E in  FIG. 3(   a ). 
     In the solar cell  40 , the collecting electrode  12  is disposed on the light-receiving surface side of the photoelectric conversion section  11 , and the collecting electrode  13  is disposed on the rear surface side. Here, the thickness of the collecting electrodes  12  and  13  in the X direction is thicker at the end portions on the photoelectric conversion section  11  than at the center portion. 
     Returning again to  FIG. 2 , after the solar cell  40  is formed in this manner (S 12 ), next disposition of adhesive layers (S 13 ) and disposition of wiring materials (S 14 ) is performed.  FIG. 6  illustrates the manner in which an adhesive layer  41  and wiring material  42  are disposed on the light-receiving surface side, and an adhesive layer  43  and wiring material  44  are disposed on the rear surface side of the solar cell  40 . 
     Returning again to  FIG. 2 , next, a crimping process is performed (S 15 ). A pair of crimping jigs that consist of a lower crimping jig  45  and an upper crimping jig  46  are used for the crimping process. The solar cell  40 , the adhesive layers  41  and  43 , and the wiring materials  42  and  44  are stacked and disposed in the order shown in  FIG. 7  between the pair of crimping jigs. That is, the wiring material  44  is disposed on the lower crimping jig  45 . The adhesive layer  43  is disposed on the wiring material  44 , the solar cell  40  is then disposed thereon so that the collecting electrode  13  that is on the rear surface side of the solar cell  40  is on the adhesive layer  43 . The adhesive layer  41  is then disposed on the collecting electrode  12  on the light-receiving surface side of the solar cell  40 , and the wiring material  42  is disposed on the adhesive layer  41 . The upper crimping jig  46  is disposed on the wiring material  42 . 
     The crimping process is performed so that, in the state shown in  FIG. 7 , the upper crimping jig  46  is relatively pressed against the lower crimping jig  45 . When the adhesive layers  41  and  43  are layers that contain thermosetting resin, pressurization and heating are performed in the crimping process. The heating is performed by incorporating a heater into the lower crimping jig  45  and the upper crimping jig  46 , passing a current to the respective heaters, and controlling the lower crimping jig  45  and the upper crimping jig  46  to a predetermined temperature. 
     As shown in  FIG. 7 , on the light-receiving surface side of the solar cell  40 , the thickness of the end portions of the collecting electrode  12  is thick and the thickness of the center portion is thin in the X direction. Therefore, when the wiring material  15  is pressed through the adhesive layer  14  by the crimping process, the pressing force with respect to the adhesive layer  14  is liable to rise at the end portions at which the collecting electrode  12  projects more, in comparison to the center portion. As a result, the adhesive layer  14  is more easily removed at the end portions of the collecting electrode  12  than at the center portion thereof, and consequently the thickness of the adhesive layer  14  becomes thinner at the end portions and thicker at the center portion. The same applies with respect to the rear surface side also. 
     Returning again to  FIG. 2 , in this way, formation of the adhesive layers  14  and  16  is performed by means of the crimping process so that, in the X direction, the thickness of portions that correspond to the center portions of the collecting electrodes  12  and  13  become thicker than the thickness of portions that correspond to the end portions A, B, C and D (S 15 ), and thus the solar cell module  10  is obtained (S 16 ). 
     A sectional view of the solar cell module  10  after the crimping process is shown in  FIG. 8 . The sectional view in  FIG. 8  corresponds to  FIG. 1 , and in  FIG. 8  the wiring materials  15  and  17  are schematically illustrated as being flat. As shown in  FIG. 8 , in the solar cell module  10 , with respect to the collecting electrodes  12  and  13 , the thickness of the end portions of the collecting electrodes  12  and  13  is formed thicker than at the center portions thereof in the X direction. Further, with respect to the adhesive layers  14  and  16 , portions that correspond to the center portions of the collecting electrodes  12  and  13  are formed thicker than portions that correspond to the end portions of the collecting electrodes  12  and  13  in the X direction. Thus, a structure can be formed in which, at the end portions on the photoelectric conversion section  11  at which current crowding is liable to arise in the wiring materials  15  and  17 , resistance components of the adhesive layers  14  and  16  decrease, mechanical joints between the wiring materials  15  and  17  and the collecting electrodes  12  and  13  are strong, and the electrical resistance is low. 
     At this time, a configuration may also be adopted in which the adhesive that serves as the adhesive layer  14  is pushed out at the end portions of the photoelectric conversion section  11  and spreads as far as the side faces of the wiring materials  15  and  17  to form a fillet. As a result, the mechanical adhesive strength of the wiring materials  15  and  17  becomes stronger. 
       FIGS. 9(   a ) and ( b   1 ) to ( b   3 ) illustrate an example in which, by appropriately setting the thickness of the plating mask  21 , the width of the end portions of the collecting electrode  12  can be made wider than the width of the center portion thereof in the X direction.  FIG. 9(   a ) is a plan view of the light-receiving surface of the solar cell  40  after electrolytic plating is performed using the plating mask  21  shown in  FIGS. 3(   a ) and ( b ).  FIGS. 9(   b   1 ), ( b   2 ), and ( b   3 ) are a sectional view of an end portion on the left side of an opening section  24  shown in  FIG. 9(   a ), a sectional view of a center portion of the opening section  24 , and a sectional view of an end portion on the right side of the opening section  24 , respectively. Here the terms “left side” and “right side” refer to the directions when the page is viewed from above. Note that the term “width of the collecting electrodes  12  and  13 ” refers, in the case of viewing the light-receiving surface or the rear surface of the photoelectric conversion section  11  from above, to a length in a direction that is perpendicular to the X direction in which the collecting electrodes  12  and  13  extend. 
     Here, a width dimension of the opening sections  22  to  24  of the plating mask  21  is denoted by “W”, and a thickness dimension is denoted by “H”. When electrolytic plating is performed, a plating thickness h 2  of the end portions of the collecting electrode  12  becomes thicker than a plating thickness h 1  of the center portion thereof. Here, the electrolytic plating conditions are set so that h 2 &gt;H&gt;h 1 . That is, formation of the collecting electrode  12  by electrolytic plating is performed until the thickness h 2  of the end portions of the collecting electrode  12  in the X direction becomes thicker than the thickness H of the plating mask  21 , and so that the thickness h 1  of the center portion of the collecting electrode  12  does not exceed the thickness H of the plating mask  21 . When the collecting electrode  12  is formed in this manner, a width w 1  of the center portion of the collecting electrode  12  is restricted by the width dimension W of the plating mask  21 , and therefore the width w 1  is such that w 1 =W. In contrast, at the end portions of the collecting electrode  12 , since the plating thickness h 2  exceeds the thickness dimension H of the plating mask  21 , the width w 2  of the collecting electrode  12  becomes wider than W. That is, the widths are such that w 2 &gt;W=w 1 . The result is the same on the rear surface side also. 
     Thus, the widths of the collecting electrodes  12  and  13  can be widened at the end portions on the photoelectric conversion section  11  at which current crowding is liable to arise in the wiring materials  15  and  17 . As a result, the structure is one in which the mechanical joints between the wiring materials  15  and  17  and the collecting electrodes  12  and  13  at the end portions on the photoelectric conversion section  11  are stronger, and the electrical resistance is lower. 
     A bright plating process and a matte plating process are available as plating processes, and enhancement of the photoelectric conversion efficiency in the solar cell module  10  can be achieved by selectively using these plating processes in a suitable manner. In particular, use of these two kinds of plating processes is effective when providing a textured structure on the surface of the solar cell  40 . 
       FIG. 10  is a view that illustrates the details of a plating process with respect to procedures for forming the solar cell  40  that has a textured structure.  FIG. 11  to  FIG. 13  are sectional views illustrating the manner in which procedures described in  FIG. 10  are performed. 
     In this case, formation of the photoelectric conversion section  11  is performed (S 20 ), and a textured structure is then formed on the surface thereof (S 21 ). The contents of S 20  are the same as in S 10  of  FIG. 2 . The textured structure formed in S 21  is a structure in which concavities and convexities are provided on the surface of the photoelectric conversion section  11 , and consequently light that is incident on the light-receiving surface of the solar cell  40  or the like is scattered thereby. A sectional view of the photoelectric conversion section  11  in which a textured structure  50  is formed is shown in  FIG. 11 . 
     Next, formation of the collecting electrode is performed, and a matte plating method is used as the plating method (S 22 ). The matte plating method is in contrast to the bright plating method. The bright plating method is a method in which a suitable bright material is added to the plating solution, and a deposition rate with respect to convex portions is controlled to thereby form a flat and bright metal layer. Therefore, if the bright plating method is used for forming a main layer of the collecting electrode, because the electrode surface will be flat, a light trapping effect will decrease and the photoelectric conversion efficiency will decline. 
       FIG. 12  is a sectional view at a time that a matte plated layer  51  is formed on the textured structure. The matte plated layer  51  formed by the matte plating method is formed in a shape that corresponds to the concavities and convexities of the textured structure  50 . 
     To further enhance the photoelectric conversion efficiency, it is good to raise the reflectivity with respect to the concavo-convex surface. Therefore, returning again to  FIG. 10 , after the matte plating process, a bright plating process is performed to adjust the shape of the substrate surface (S 23 ).  FIG. 13  is a sectional view at a time that a bright plated layer  52  is formed on the matte plated layer  51  that has concavities and convexities on the surface thereof. 
     Since the structure in this case is one for ensuring that the concavities and convexities on the surface of the matte plated layer  51  having a high light trapping effect are left as they are, the bright plated layer that is formed here may have a thin thickness. If the metal surface of the matte plated layer  51  has a sufficient light trapping effect, the bright plating process need not be performed. A layered product in which the bright plated layer  52  is formed on the matte plated layer  51  corresponds to the collecting electrode  12  that was described above using  FIG. 1  and  FIG. 8 . Note that although, as described with respect to  FIG. 1  and  FIG. 8 , the thickness of the collecting electrode  12  formed by the plating method is thick at the ends and thin at the center portion in the X direction of the photoelectric conversion section  11 , regardless of the thickness of the collecting electrode  12 , the surface of the layered product of the matte plated layer  51  and the bright plated layer  52  has concavities and convexities that reflect the concavities and convexities of the textured structure  50 . 
       FIG. 14  is a sectional view of a solar cell module  60  that uses a solar cell  53  formed as illustrated in  FIG. 13 . The solar cell  53  is a solar cell in which a collecting electrode that is constituted by the matte plated layer  51  and the bright plated layer  52  is formed on the photoelectric conversion section  11 . The solar cell module  60  is formed by disposing a filler  62  between the solar cell  53  and a protective member  61  on the light-receiving surface side. A transparent plate body or film is used as the protective member on the light-receiving surface side. For example, a translucent member such as a glass plate, a resin plate or a resin film can be used. A member that is the same as the protective member on the light-receiving surface side can be used as a protective member on the rear surface side. EVA, EEA, PVB, a silicon-based resin, a urethane-based resin, an acrylic resin, an epoxy-based resin or the like can be used as the filler. 
     In  FIG. 14 , when light that passes through the protective member  61  and the filler  62  is incident on the collecting electrode  12 , the light is scattered by the concavities and convexities on the surface of the collecting electrode  12 . Although some of the scattered light reaches the textured structure  50  as it is, part of the scattered light travels in the direction of the protective member  61 . Since the light that travels in the direction of the protective member  61  is scattered light whose directivity is not uniform due to the concavities and convexities on the surface of the collecting electrode  12 , the scattered light arrives at the boundary surface between the protective member  61  and the outside air at diverse angles, and the light is totally reflected at the aforementioned boundary surface and returned in the direction of the textured structure  50 . 
     By forming the matte plated layer  51  on the textured structure  50  in this manner, the surface thereof serves as concavities and convexities, and hence incident light can be converted to scattered light to thereby improve the photoelectric conversion efficiency of the solar cell module  60 . 
     REFERENCE SIGNS LIST 
       10 ,  60  solar cell module,  11  photoelectric conversion section,  12 ,  13  collecting electrode,  14 ,  16 ,  41 ,  43  adhesive layer,  15 ,  17 ,  42 ,  44  wiring material,  20  substrate with a plating mask,  21  plating mask,  22 ,  23 ,  24  opening section,  25 ,  26 ,  27 ,  28  power supply terminal,  30  plating bath,  31  plating solution,  32 ,  33  anode plate,  34 ,  35  plating power source,  40 ,  53  solar cell,  45  lower crimping jig,  46  upper crimping jig,  50  textured structure,  51  matte plated layer,  52  bright plated layer,  61  protective member,  62  filler