Abstract:
While using the same laser device, a slit (S 4 ) is formed by cutting an photoelectric conversion unit and a backside electrode formed over a transparent electrode to a surface of the transparent electrode and a slit (S 5 ) is formed by cutting the photoelectric conversion unit and the backside electrode formed in a slit (S 2 ) of the transparent electrode in a direction intersecting a direction of the slit S 4.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The disclosure of Japanese Patent Application No. 2009-124261 filed on May 22, 2009, including specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a method of manufacturing a solar cell module. 
         [0004]    2. Related Art 
         [0005]    Solar cell modules are known in which semiconductor thin films such as amorphous and microcrystalline semiconductor thin films are layered. In particular, a solar cell module in which microcrystalline silicon or amorphous silicon thin film is used has attracted much attention in view of resource consumption, reduction of cost, and improvement in efficiency. 
         [0006]      FIG. 3  is a cross sectional schematic diagram of a basic structure of a solar cell module  100 . The solar cell module  100  generally has a structure in which a transparent electrode  12 , an photoelectric conversion unit  14 , and a backside electrode  16  are layered over a transparent substrate  10  such as glass, and generates power by incident of light through the transparent substrate  10 . 
         [0007]    A manufacturing method and a patterning device for integrating such solar cell modules in series are known in various references. For example, a configuration is known in which, during patterning with a laser, the structure is processed while gas is blown onto the structure. 
         [0008]      FIGS. 4A-4F  show a manufacturing process of the solar cell module  100  in related art.  FIGS. 4A-4F  schematically show plan views and cross sectional views in the steps of the manufacturing process of the solar cell module  100 . The cross sectional views are cross sectional views along a line A-A in the plan view and cross sectional views along a line B-B in the plan view. 
         [0009]    In step S 10 , as shown in  FIG. 4A , through laser patterning, a slit S 1  which divides the transparent electrode  12  formed over the transparent substrate  10  is formed, and a slit S 2  is formed in a direction perpendicular to the slit S 1 . In step S 12 , as shown in  FIG. 4B , a film of the photoelectric conversion unit  14  is formed covering the transparent electrode  12 . As the photoelectric conversion unit  14 , an amorphous silicon (a-Si) photoelectric conversion unit, a microcrystalline silicon (μc-Si) photoelectric conversion unit, or a tandem structure of these units may be employed. In step S 14 , as shown in  FIG. 4C , through laser patterning, a slit S 3  which divides the photoelectric conversion unit  14  is formed at a position near the slit S 1  and not overlapping the slit S 1 , along the direction of the slit S 1 . In step S 16 , as shown in  FIG. 4D , the backside electrode  16  is formed covering the photoelectric conversion unit  14 . Instep S 18 , as shown in  FIG. 4E , through laser patterning, a slit S 4  which divides the photoelectric conversion unit  14  and the backside electrode  16  is formed at a position near the slit S 3  and not overlapping the slits S 1  and S 3 , along the direction of the slits S 1  and S 3 . With such a process, a structure is obtained in which a plurality of solar cells are connected in series along the direction of the slit S 2 . In step S 20 , as shown in  FIG. 4F , through laser patterning, a slit S 5  which divides the photoelectric conversion unit  14  and the backside electrode  16  formed in the slit S 2  is formed. As a result, a structure is obtained in which solar cells which are adjacent to each other along the direction of the slit S 1  are electrically separated from each other and a plurality of groups of solar cells each comprising a plurality of solar cells connected in series are provided in parallel to each other. The groups of solar cells are ultimately connected in parallel with each other, and the solar cell module  100  is formed. 
         [0010]    A laser device for patterning the slits S 3  and S 4  is made for integrating a large number of solar cells in series along the direction of the slit S 2 , and typically is not suited for patterning in a direction perpendicular to the directions of the slits S 3  and S 4 . 
         [0011]    For example, the laser device for patterning the slits S 3  and S 4  has a rectangular laser beam shape, and, because the optimum values for the patterning conditions for dividing the photoelectric conversion unit  14  and the backside electrode  16  differ between the direction along the slits S 3  and S 4  and the direction perpendicular to this direction, it has been difficult to find an optimum patterning condition in both dividing directions. 
         [0012]    In addition, in the laser device for patterning the slits S 3  and S 4 , in order to simultaneously form the plurality of slits S 3  and S 4  in the direction of integration of the solar cells for the purpose of improving the patterning speed, a plurality of laser beam emission holes are placed at equal spacing, and, when the patterning in the direction perpendicular to the slits S 3  and S 4  is executed, a plurality of laser beam patterning lines overlap each other, and, thus, the laser device is not suited for patterning the slit S 5 . 
         [0013]    Because of this, the slit S 5  in the direction perpendicular to the slit S 4  cannot be formed by the laser device for forming the slit S 4 , and the laser device must be changed at steps S 18  and S 20 , which results in a problem in that the time required for manufacturing is increased. 
       SUMMARY 
       [0014]    According to one aspect of the present invention, there is provided a method of manufacturing a solar cell module comprising a first step in which a transparent conductive film formed over a substrate is cut using a first laser device in a first direction to form a first channel and in a second direction intersecting the first direction to form a second channel; a second step in which an photoelectric conversion film formed over the transparent conductive film is cut using a second laser device along the first direction and to a surface of the transparent conductive film to form a third channel; and a third step in which the photoelectric conversion film and an electrode film formed over the transparent conductive film are cut using a third laser device along the first direction and to the surface of the transparent conductive film to form a fourth channel, and the photoelectric conversion film and the electrode film formed in the second channel are cut using the third laser device along the second direction to form a fifth channel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A preferred embodiment of the present invention will be described in further detail based on the following drawings, wherein: 
           [0016]      FIG. 1A  is a plan view and cross sectional views showing a step S 30  of a manufacturing process of a solar cell module according to a preferred embodiment of the present invention; 
           [0017]      FIG. 1B  is a plan view and cross sectional views showing a step S 32  of the manufacturing process of the solar cell module according to the preferred embodiment of the present invention; 
           [0018]      FIG. 1C  is a plan view and cross sectional views showing a step S 34  of the manufacturing process of the solar cell module according to the preferred embodiment of the present invention; 
           [0019]      FIG. 1D  is a plan view and cross sectional views showing a step S 36  of the manufacturing process of the solar cell module according to the preferred embodiment of the present invention; 
           [0020]      FIG. 1E  is a plan view and cross sectional views showing a step S 38  of the manufacturing process of the solar cell module according to the preferred embodiment of the present invention; 
           [0021]      FIG. 2  is a diagram for explaining a spot of a laser beam emitted from a laser device in the preferred embodiment of the present invention; 
           [0022]      FIG. 3  is a diagram showing a basic structure of a solar cell module; 
           [0023]      FIG. 4A  is a plan view and cross sectional views showing a step S 10  of a manufacturing process of a solar cell module in the related art; 
           [0024]      FIG. 4B  is a plan view and cross sectional views showing a step S 12  of the manufacturing process of the solar cell module in the related art; 
           [0025]      FIG. 4C  is a plan view and cross sectional views showing a step S 14  of the manufacturing process of the solar cell module in the related art; 
           [0026]      FIG. 4D  is a plan view and cross sectional views showing a step S 16  of the manufacturing process of the solar cell module in the related art; 
           [0027]      FIG. 4E  is a plan view and cross sectional views showing a step S 18  of the manufacturing process of the solar cell module in the related art; and 
           [0028]      FIG. 4F  is a plan view and cross sectional views showing a step S 20  of the manufacturing process of the solar cell module in the related art. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIGS. 1A-1E  show a manufacturing process of a solar cell module  100  according to a preferred embodiment of the present invention.  FIGS. 1A-1E  schematically show plan views and cross sectional views in the steps of the manufacturing process of the solar cell module  100 . The cross sectional views are cross sectional views along a line C-C in the plan view and cross sectional views along a line D-D in the plan view. 
         [0030]    In step S 30 , as shown in  FIG. 1A , through laser patterning, a slit S 1  (in a left and right direction in the figure) which divides a transparent electrode  12  formed over a transparent substrate  10  is formed, and a slit S 2  (in an up and down direction in the figure) is formed in a direction perpendicular to the slit S 1 . The transparent substrate  10  is made of a material which passes light of a wavelength which is used in the photoelectric conversion in the solar cell, and, for example, glass, plastic, or the like may be used. For the transparent electrode  12 , a transparent conductive oxide (TCO) in which tin oxide (SnO 2 ), zinc oxide (ZnO), indium tin oxide (ITO), or the like is doped with tin (Sn), antimony (Sb), fluorine (F), aluminum (Al), or the like may be used. 
         [0031]    A laser device for forming the slits S 1  and S 2  preferably uses YAG laser of a wavelength of 1064 nm. Power of the laser beam emitted from the laser device is adjusted and the laser beam is radiated from the side of the transparent electrode  12  and consecutively scanned in the direction of the slit S 1  and the direction of the slit S 2  perpendicular to the direction of the slit S 1 , to form the slits S 1  and S 2 . Alternatively, the laser for forming the slits S 1  and S 2  may be radiated from the side of the transparent substrate  10 . 
         [0032]    Because a large number of slits S 1  must be formed in order to integrate a large number of solar cells in series, it is also preferable to use a laser device of a multi-emission type in which a plurality of laser beam emission holes are provided at equal spacing along the direction perpendicular to the slit S 1 . For example, a laser device having 2-5 laser beam emission holes is preferably used. With this configuration, it is possible to rapidly form a large number of slits S 1  for integrating a large number of solar cells in series. Because the slit S 2  is greater in size than the other slits and a patterning precision of the slit S 2  may be lower than that of the other slits, the patterning conditions can be easily set even when the multi-emission type laser device is used. 
         [0033]    In step S 32 , as shown in  FIG. 1B , a film of an photoelectric conversion unit  14  is formed covering the transparent electrode  12  and the slits S 1  and S 2 . No particular limitation is imposed on the photoelectric conversion unit  14 , and, for example, an amorphous silicon (a-Si) photoelectric conversion unit, a microcrystalline silicon (μc-Si) photoelectric conversion unit, or a tandem structure of these units may be used. The photoelectric conversion unit  14  may be formed through plasma CVD or the like. 
         [0034]    In step S 34 , as shown in  FIG. 1C , a slit S 3  which divides the photoelectric conversion unit  14  is formed through laser patterning. The slit S 3  is formed at a position near the slit S 1  and not overlapping the slit S 1 , along the direction of the slit S 1 , and to a surface of the transparent electrode  12 . 
         [0035]    A laser device for forming the slit S 3  preferably uses YAG laser of a wavelength of 532 nm (second harmonics). Power of the laser beam emitted from the laser device is adjusted, and the laser beam is radiated from the side of the transparent substrate  10  and scanned in the direction of the slit S 3 , to form the slit S 3 . 
         [0036]    In step S 36 , as shown in  FIG. 1D , a backside electrode  16  is formed covering the photoelectric conversion unit  14  and the slit S 3 . For the backside electrode  16 , a reflective metal is preferably used. Alternatively, it is also preferable to employ a layered structure of the reflective metal and a transparent conductive oxide (TCO). As the reflective metal, silver (Ag), aluminum (Al), or the like may be used. As the transparent conductive oxide (TCO), tin oxide (SnO 2 ), zinc oxide (ZnO), indium tin oxide (ITO), or the like may be used. 
         [0037]    In step S 38 , as shown in  FIG. 1E , slits S 4  and S 5  which divide the photoelectric conversion unit  14  and the backside electrode  16  are formed through laser patterning. The slit S 4  is formed at a position near the slit S 3  and not overlapping the slits S 1  and S 3 , along the direction of the slits S 1  and S 3 , and to a surface of the transparent electrode  12  to divide the photoelectric conversion unit  14  and the backside electrode  16 . With this process, a structure is obtained in which a plurality of solar cells are connected in series along the direction of the slit S 2 . Similarly, the slit S 5  is formed in a region where the slit S 2  is formed and to the surface of the transparent electrode  12  to divide the photoelectric conversion unit  14  and the backside electrode  16  formed in the slit S 2 . With the slit S 5 , solar cells adjacent in the direction of the slit S 1  are electrically separated from each other. Because the slit S 5  is formed in the region where the slit S 2  is formed, laser light can be radiated from the transparent electrode  12 , and the slit S 5  can be formed consecutively from the formation of the slit S 4 . 
         [0038]    As described, the slits S 1 , S 3 , and S 4  are formed in order to connect a group of adjacent solar cells in series, and the slits S 2  and S 5  are formed to set groups of the solar cells, which are connected in series, in parallel to each other. With this configuration, a structure is obtained in which the solar cells adjacent along the direction of the slit S 1  are electrically separated from each other and a plurality of groups of solar cells each having a plurality of solar cells connected in series are provided in parallel to each other. The solar cell groups are ultimately connected in parallel, and the solar cell module  100  is formed. 
         [0039]    A laser device for forming the slits S 4  and S 5  preferably uses YAG laser of a wavelength of 532 nm (second harmonics). Power of the laser beam emitted from the laser device is adjusted, and the laser beam is radiated from the side of the transparent substrate  10  and consecutively scanned in the directions of the slits S 4  and S 5 , to form the slits S 4  and S 5 . 
         [0040]    A laser device for forming the slits S 4  and S 5  radiates a single laser beam having a laser spot where a diameter D 1  in a direction along the slit S 4  and a diameter D 2  in a direction along the slit S 5  are approximately equal to each other, as shown in  FIG. 2 . For example, a laser device having a laser spot of an approximate circular shape or an approximate square shape is used. 
         [0041]    With this configuration, the optimum values of the patterning conditions are close to each other between the direction along the slit S 4  and the direction perpendicular to this direction and along the slit S 5 , and, thus, the optimum patterning condition can be easily set in both dividing directions. 
         [0042]    In addition, through patterning with a single laser beam, even when the patterning direction is changed, the patterning lines produced by a plurality of laser beams are not overlapped with each other, and the slits S 4  and S 5  can be easily formed with a single laser device. 
         [0043]    Alternatively, steps such as a step for removing an outer peripheral portion of the solar cell module  100  may be provided after step S 38 . 
         [0044]    As described, according to the present embodiment, the laser device does not need to be changed between the time when the slit S 4  is formed and the time when the slit S 5  is formed, and, thus, the manufacturing process of the overall solar cell module can be simplified. With such a configuration, the time required for the manufacturing can be shortened.