Patent Publication Number: US-2011064984-A1

Title: Solar battery module substrate and solar battery module

Description:
This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2009-215897 filed in Japan on Sep. 17, 2009, the entire contents of which are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a solar battery module substrate and a solar battery module. 
     BACKGROUND ART 
     A silicon-based solar battery cell has an electromotive force of approximately 0.5V, and there is a case where an electromotive force of one solar battery cell is not sufficient to operate a desired electric circuit. Accordingly, in a conventional art, a plurality of solar battery cells are connected with each other in series to form a solar battery module, thereby obtaining an electromotive force necessary for a desired electric circuit. 
     On the other hand, a solar battery cell having a cathode and an anode for extracting an electric force at the back solar battery cell) is expected as a highly efficient solar battery cell which does not suffer from a drop in optical power generation performance due to the shades of electrodes formed on the front surface of the solar battery cell, compared with a conventional solar battery cell having a cathode and an anode for extracting an electric force on a back surface and a front surface, respectively. 
       FIG. 18  is an explanatory drawing showing operations of a conventional back surface electrode type solar battery cell  101 . (a) to (c) of  FIG. 18  are drawings showing operations of the conventional back surface electrode type solar battery cell  101 . In the drawing, since the back surface electrode type solar battery cell  101  is used for a later-mentioned large solar battery module for housing etc., the back surface electrode type solar battery cell  101  is made of a whole wafer. A front surface  102  of the back surface electrode type solar battery cell  101  shown in (a) of  FIG. 18  has a textual structure for preventing reflection of light, and incident light  104  from the sun  103  is incident to the front surface  102 . 
     Further, as shown in (b) of  FIG. 18 , on a back surface  105  of the back surface electrode type solar battery cell  101 , positive electrodes (cathodes)  106  and negative electrodes (anodes)  107  are positioned alternately (striped manner). In  FIG. 18 , the positive electrodes  106  and the negative electrodes  107  are not exposed at edges of the back surface electrode type solar battery cell  101 . This is because the positive electrodes  106  and the negative electrodes  107  are not extended to the edges of the back surface electrode type solar battery cell  101  in consideration of holding peripherals of a wafer in wafer processing. 
     When the incident light  104  is incident to the back surface electrode type solar battery cell  101 , an electron-hole pair  108  is excited in the back surface electrode type solar battery cell  101 , as shown in (c) of  FIG. 18  which is a cross sectional drawing taken in A-A″ line which is a part of a cross sectional drawing taken in A-A′ line of (b) of  FIG. 18 . Among the excited electron-hole pair  108 , an electron  109  reaches the negative electrode  107  and a hole  110  reaches the positive electrode  106 . Thus, it is possible to extract an electromotive force from the back surface electrode type solar battery cell  101 . As a distance W  101  between the positive electrode  106  and the negative electrode  107  is shorter, the efficiency of the back surface electrode type solar battery cell  101  increases. 
     As a solar battery including the back surface electrode solar battery cell, Patent Literature 1 discloses a solar battery in which electrodes of a solar battery cell are electrically connected with wiring of a wiring substrate at a low temperature with easiness. Electrodes of the back surface electrode type solar battery cell are electrically connected with wiring of a wiring substrate and the cell is sealed with a sealing member. Thus, a solar battery module is provided. 
     Citation List 
     [Patent Literature] 
     [Patent Literature 1] 
     Japanese Patent Application Publication Tokukai No. 2009-88145 (publication date: Apr. 23, 2009). 
     SUMMARY OF INVENTION 
     Technical Problem 
     The solar battery cell and the solar battery module disclosed in Patent Literature 1 are made of a wafer without cutting it. In the vicinity of the edges, there is a portion where terminals cannot be provided due to wafer processing, and where contact etc. with an electrode is not made. However, for example, in a case where a cell designed to be used as a module while maintaining its wafer size is cut into a plurality of modules, there arises a problem that an electrode is exposed in the vicinity of edges and contacts with its surrounding. Such problem has not been discussed so far. 
     The present invention was made in view of the foregoing problem. An object of the present invention is to provide a solar battery module substrate and a solar battery module in each of which an exposed electrode does not touch with its surrounding. 
     Solution to Problem 
     In order to solve the foregoing problem, a solar battery module substrate of the present invention on which solar battery cells are to be mounted includes an insulating substrate on which a conductive pattern and an insulating protective film are formed, the conductive pattern including: cathode mounting terminals each of which is to be connected with a cathode of a solar battery cell; anode mounting terminals each of which is to be connected with an anode of the solar battery cell; and first module wiring, the first module wiring connecting a cathode mounting terminal to be connected with a cathode of one solar battery cell with an anode mounting terminal to be connected with an anode of another solar battery cell connected in series with said one solar battery cell, the insulating protective film having at least one opening for exposing the cathode mounting terminal and the anode mounting terminal, and the opening being positioned inside a portion of the solar battery module substrate on which portion the solar battery cell is to be projected. 
     With the invention, the solar battery module substrate includes the insulating protective film having at least one opening. This allows electrical connection between the solar battery cell and the conductive pattern. Further, even if a part of an electrode of the solar battery cell is exposed, i.e. even if a portion where an electrode is exposed appears, provision of the insulating protective film between the portion where the electrode is exposed and the first module wiring prevents the portion where the electrode is exposed and the first module wiring from contacting with each other improperly. 
     Further, a cell distance between two solar battery cells on the solar battery module substrate of the present invention can be smaller than a cell distance on a conventional solar battery module substrate. Accordingly, a solar battery module including the solar battery module substrate can output an electromotive force corresponding to its size. 
     A solar battery module substrate of the present invention on which solar battery cells are to be mounted includes an insulating substrate on which a conductive pattern and a first insulating protective film are formed, the conductive pattern including: cathode mounting terminals each of which is to be connected with a cathode of a solar battery cell; anode mounting terminals each of which is to be connected with an anode of the solar battery cell; and first module wiring, the first module wiring connecting a cathode mounting terminal to be connected with a cathode of one solar battery cell with an anode mounting terminal to be connected with an anode of another solar battery cell connected in series with said one solar battery cell, the first insulating protective film having at least one first opening for exposing the cathode mounting terminal and at least one second opening for exposing the anode mounting terminal, said at least first opening and said at least one second opening being positioned inside a portion of the solar battery module substrate on which portion the solar battery cell is to be projected, and a second insulating protective film being provided between the cathode mounting terminal and the anode mounting terminal. 
     With the invention, the solar battery module substrate includes the insulating protective film having at least one first opening and at least one second opening. This allows electrical connection between the solar battery cell and the conductive pattern. Further, even if a part of an electrode of the solar battery cell is exposed, i.e. even if a portion where an electrode is exposed appears, provision of the insulating protective film between the portion where the electrode is exposed and the first module wiring prevents the portion where the electrode is exposed and the first module wiring from contacting with each other improperly. 
     Further, a cell distance between two solar battery cells on the solar battery module substrate of the present invention can be smaller than a cell distance on a conventional solar battery module substrate. Accordingly, a solar battery module including the solar battery module substrate can output an electromotive force corresponding to its size. 
     Further, provision of the first opening, the second opening, and the second insulating protective film allows more surely insulating between the cathode mounting terminal and the anode mounting terminal in electrical connection between the solar battery cell and the conductive pattern. Further, provision of the second insulating protective film allows dispersing strength applied on the solar battery module substrate when the solar battery cell is mounted on the solar battery module substrate, and allows smoother sealing by transparent protective resin. 
     ADVANTAGEOUS EFFECTS OF INVENTION 
     As described above, the solar battery module substrate of the present invention on which solar battery cells are to be mounted includes an insulating substrate on which a conductive pattern and an insulating protective film are formed, the conductive pattern including: cathode mounting terminals each of which is to be connected with a cathode of a solar battery cell; anode mounting terminals each of which is to be connected with an anode of the solar battery cell; and first module wiring, the first module wiring connecting a cathode mounting terminal to be connected with a cathode of one solar battery cell with an anode mounting terminal to be connected with an anode of another solar battery cell connected in series with said one solar battery cell, the insulating protective film having at least one opening for exposing the cathode mounting terminal and the anode mounting terminal, and the opening being positioned inside a portion of the solar battery module substrate on which portion the solar battery cell is to be projected. 
     As described above, the solar battery module substrate of the present invention on which solar battery cells are to be mounted includes an insulating substrate on which a conductive pattern and a first insulating protective film are formed, the conductive pattern including: cathode mounting terminals each of which is to be connected with a cathode of a solar battery cell; anode mounting terminals each of which is to be connected with an anode of the solar battery cell; and first module wiring, the first module wiring connecting a cathode mounting terminal to be connected with a cathode of one solar battery cell with an anode mounting terminal to be connected with an anode of another solar battery cell connected in series with said one solar battery cell, the first insulating protective film having at least one first opening for exposing the cathode mounting terminal and at least one second opening for exposing the anode mounting terminal, said at least first opening and said at least one second opening being positioned inside a portion of the solar battery module substrate on which portion the solar battery cell is to be projected, and a second insulating protective film being provided between the cathode mounting terminal and the anode mounting terminal. 
     Therefore, the present invention provides a solar battery module substrate and a solar battery module in each of which a portion where an electrode is exposed does not contact with its surrounding improperly. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plane drawing showing a solar battery module substrate in accordance with an embodiment of the present invention. 
         FIG. 2  is an explanatory drawing showing operations of a back surface electrode type solar battery cell. (a)-(c) of  FIG. 2  show operations of a back surface electrode type solar battery cell. 
         FIG. 3  is a drawing showing production of a back surface electrode type solar battery cell from a back surface electrode type cell wafer for housing. (a)-(c) of  FIG. 3  shows production of a back surface electrode type solar battery cell from a back surface electrode type cell wafer for housing. 
         FIG. 4  is a plane drawing showing a module substrate in accordance with an embodiment of the present invention. 
         FIG. 5  is a plane drawing showing a module substrate to which solder paste is supplied. 
         FIG. 6  is a drawing showing mounting a back surface electrode type solar battery cell in an inverted manner. 
         FIG. 7  is a plane drawing showing a solar battery module completed by being sealed with transparent protective resin, in accordance with the present embodiment. 
         FIG. 8  is a cross sectional drawing taken in line A-B of the solar battery module substrate shown in  FIG. 1 . 
         FIG. 9  is a plane drawing showing another solar battery module substrate in accordance with an embodiment of the present invention. 
         FIG. 10  is a plane drawing showing still another solar battery module in accordance with an embodiment of the present invention. (a) of  FIG. 10  is a plane drawing showing a front surface of the solar battery module. (b) of  FIG. 10  shows a plane drawing showing a back surface of the solar battery module. 
         FIG. 11  is a plane drawing showing a back surface of a back surface electrode type solar battery cell on which back surface positive electrodes and negative electrodes are positioned in a checkered pattern. 
         FIG. 12  is an explanatory drawing showing how to make a back surface electrode type solar battery cell from a back surface electrode type cell wafer for housing. (a)-(c) of  FIG. 12  show how to make a back surface electrode type solar battery cell from a back surface electrode type cell wafer for housing. 
         FIG. 13  is a plane drawing showing a module substrate for the purpose of preliminary discussion. 
         FIG. 14  is a plane drawing showing a module substrate to which solder paste is supplied, for the purpose of preliminary discussion. 
         FIG. 15  is a drawing showing mounting a back surface electrode type solar battery cell in an inverted manner. 
         FIG. 16  is a plane drawing showing a solar battery module completed by being sealed with transparent protective resin. 
         FIG. 17  is a drawing showing providing a broad cell distance on a solar battery module. 
         FIG. 18  is an explanatory drawing showing operations of a conventional back surface electrode type solar battery cell. (a) to (c) of  FIG. 18  are drawings showing operations of the conventional back surface electrode type solar battery cell. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     One embodiment of the present invention is explained below with reference to  FIGS. 1 to 17 . 
     Preliminary discussion on a back surface electrode type solar battery cell will be made here with reference to  FIGS. 12-17 . 
     An explanation is made as to a case where a back surface electrode type solar battery cell is made by cutting a wafer in order that the back surface electrode type solar battery cell may have any module size (i.e. chip size).  FIG. 12  is an explanatory drawing showing how to make the back surface electrode type solar battery cell from a back surface electrode type cell wafer for housing. Here, it is assumed that a back surface electrode type cell wafer  111  shown in (a) of  FIG. 12  is cut into cells as shown in (b) of  FIG. 12 . 
     In this case, there is a possibility that a part of a positive electrode (cathode)  116  and a part of a negative electrode (anode)  117  are exposed at edges T (cell edges) of a back surface electrode type solar battery cell  111 ′ having been cut as shown in (c) of  FIG. 12 . A length of the exposed part of the electrode is approximately several μm. 
     In  FIG. 12 , the back surface electrode type cell wafer  111  is used for housing as it is, i.e. without cutting the back surface electrode type cell wafer  111 . Cutting of the wafer in (b) of  FIG. 12  is performed with a circular saw. Thus, the back surface electrode type solar battery cell  111 ′ having a predetermined size (shown in (c) of  FIG. 12 )) is obtained. 
     The following explains mounting the back surface electrode type solar battery cell  111 ′. On a solar battery module substrate  112  of  FIG. 13 , there are provided module wiring  113 , a cathode mounting terminal  114  connected with the module wiring  113 , and an anode mounting terminal  115  connected with the module wiring  113 . 
     Subsequently, a solder paste  118  is supplied to the solar battery module substrate  112  as shown in  FIG. 14  (solder printing). The solder paste  118  is supplied only to a portion where the solder paste  118  is required, i.e. the cathode mounting terminal  114  and the anode mounting terminal  115 . A conductive adhesive may be used instead of the solder paste  118 . 
     Further, on the solar battery module substrate  112  to which the solder paste  118  has been supplied, the back surface electrode type solar battery cell  111 ′ is mounted as a flip chip, i.e. in an inverted manner, as shown in  FIG. 15 . Then, the whole of the solar battery module substrate  112  on which the back surface electrode type solar battery cell  111 ′ has been mounted is sealed with transparent protective resin  117  as shown in  FIG. 16 . Thus, a solar battery module  119  is completed. 
     In the solar battery module  119 , when the back surface electrode type solar battery cells  111 ′ each having on its back surface a cathode and an anode from which an electric power can be extracted are connected with each other in series to have a larger electromotive force, it is necessary to insulate between the cathode of the back surface electrode type solar battery cell  111 ′ and the anode of the same back surface electrode type solar battery cell  111 ′ and between the cathode of one of two back surface electrode type solar battery cells  111 ′ connected with each other in series and the anode of the other. 
     However, there is a case where the exposed portion of the electrode appears at portions indicated by arrows in the solar battery module  119  in  FIG. 17 . Therefore, it is necessary to design the solar battery module  119  such that an exposed part of the electrode at an edge T of the back surface electrode type solar battery cell  111 ′ does not improperly contact with the module wiring  113  when the back surface electrode type solar battery cell  111 ′ is mounted on the solar battery module substrate  112 . This necessitates widening a cell distance D 111 ′. 
     As described above, the solar battery module  119  obtained by connecting the back surface electrode type solar battery cells  111 ′ in series on the solar battery module substrate  112  has large cell distance D 111 ′ between two solar battery cells. Consequently, the solar cell module  119  gets larger and unable to output an electromotive force corresponding to the size of the solar battery module  119 . Consequently, the solar cell module cannot fully exhibit its feature of not suffering from a drop in optical power generation performance. 
     The present invention was made as a result of the preliminary discussion on a back surface electrode type solar battery cell. 
       FIG. 1  is a plane drawing showing a solar battery module substrate in accordance with the present embodiment. The solar battery module substrate  1  includes, on an insulating substrate, an insulating protective film  2  (insulating protective film, first insulating protective film), a cathode mounting terminal  3   a , an anode mounting terminal  3   b , module wiring  4   a  connected with the cathode mounting terminal  3   a , and module wiring  4   b  connected with the anode mounting terminal  3   b . The insulating substrate is made of glass epoxy for example. 
     The insulating protective film  2  includes an opening  2   o  (opening). The opening  2   o  is for exposing the cathode mounting terminal  3   a  and the anode mounting terminal  3   b , and is provided inside a portion indicted by thick line in  FIG. 1 , i.e. a portion where a back surface electrode type solar battery cell  5  (solar battery cell) is projected. 
     Mounting a back surface electrode type solar battery cell  5  (mentioned later) on the solar battery module substrate  1  and sealing the solar battery module substrate  1  with transparent protective resin  6  results in a solar battery module  7 . 
       FIG. 2  is an explanatory drawing showing operations of the back surface electrode type solar battery cell  5 . (a) to (c) of  FIG. 2  show the operations of the back surface electrode type solar battery cell  5 . The back surface electrode type solar battery cell is a solar battery cell having a positive electrode and a negative electrode on its back surface and having no electrodes (no positive electrode and no negative electrode) on its front surface. 
     A surface  12  of the back surface electrode type solar battery cell  5  shown in (a) of  FIG. 2  has a texture structure for preventing reflection of light, and incident light  14  from the sun  13  is incident to the surface  12 . 
     Further, as shown in (b) of  FIG. 2 , on a back surface  15  of the back surface electrode type solar batter cell  5 , a positive electrode (cathode)  16  and a negative electrode (anode)  17  are positioned alternately (in a striped manner). The shape of the positive electrode  16  and the negative electrode  17  is a rectangular parallelepiped, and the length of a long side of the rectangular parallelepiped is equal to the length of a side of the back surface electrode type solar battery cell  5 . 
     When the incident light  14  is incident to the back surface electrode type solar battery cell  5  having the above configuration, an electron-hole pair  18  is excited in the back surface electrode type solar battery cell  5  as shown in (c) of  FIG. 2 . Out of the excited electron-hole pair  18 , an electron  19  reaches the negative electrode  17  and the hole  20  reaches the positive electrode  16 . This allows extracting an electromotive force from the back surface electrode type solar battery cell  5 . As a distance W 1  between the positive electrode  16  and the negative electrode  17  is shorter, the efficiency of the back surface electrode type solar battery cell  5  increases. The distance W 1  is 0.75 mm for example. 
       FIG. 3  is a drawing showing production of the back surface electrode type solar battery cell  5  from a back surface electrode type cell wafer  21  for housing. The back surface electrode type solar battery cell  5  shown in  FIG. 2  may be produced by cutting, as shown in (b) of  FIG. 3 , the back surface type electrode cell wafer  21  for housing shown in (a) of  FIG. 3 . 
     In this case, there is a possibility that a part of a positive electrode  16  and a part of a negative electrode  17  are exposed at edges T of the back surface electrode type solar battery cell  5  shown in (c) of  FIG. 3 . A length of the exposed part of the electrode is approximately several μm. 
     In  FIG. 3 , the back surface electrode type cell wafer  21  is used for housing as it is, i.e., without cutting the back surface electrode type cell wafer  21 . Cutting in (b) of  FIG. 3  is performed with a circular saw. Thus, the back surface electrode type solar battery cell  5  having a predetermined size (shown in (c) of  FIG. 3 )) is obtained. 
     The following explains mounting the back surface electrode type solar battery cell  5 .  FIG. 4  is a plane drawing illustrating the solar battery module substrate  22  of the present embodiment. On a solar battery module substrate  22  of  FIG. 4 , there are provided module wiring  4   a , module wiring  4   b , module wiring  23  (first module wiring), a cathode mounting terminal  24  connected with the module wiring  23 , and an anode mounting terminal  25  connected with the module wiring  23 . The module wiring  4   a , the module wiring  4   b , the module wiring  23 , the cathode mounting terminal  24 , and the anode mounting terminal  25  constitute a conductive pattern. The module wiring  23  includes the module wiring  4   a  and the module wiring  4   b.    
     Further, the insulating protective film  2  is provided so as to cover the whole of the solar battery module substrate  22 , i.e. the module wiring  23 , the cathode mounting terminal  24 , and the anode mounting terminal  25 . The insulating protective film  2  has an opening  2   o.    
     Subsequently, a solder paste  26  is supplied to the solar battery module substrate  22  as shown in  FIG. 5  (solder printing). The solder paste  26  is supplied only to a portion where the solder paste  26  is required, i.e. the cathode mounting terminal  24  and the anode mounting terminal  25 . 
     Further, on the solar battery module substrate  22  to which the solder paste  26  has been supplied, the back surface electrode type solar battery cell  5  is mounted as a flip chip, i.e. in an inverted manner, as shown in  FIG. 6 . Then, the whole of the solar battery module substrate  22  on which the back surface electrode type solar battery cell has been mounted is sealed with transparent protective resin  6  as shown in  FIG. 7 . Thus, a solar battery module  7  is completed. 
     In the above example, connection is made using a solder paste. Alternatively, connection may be made using a conductive adhesive, an anisotropic conductive sheet etc. 
     In the solar battery module  7  having the above configuration, the solar battery module substrate  1  includes the insulating protective film  2  having at least one opening  2   o . This allows electrical connection between the back surface electrode type solar battery cell  5  and the conductive pattern. Further, even if a part of an electrode of the back surface electrode type solar battery cell  5  (a part of the positive electrode  16  or a part of the negative electrode  17 ) is exposed at a portion indicated by an arrow of an edge T of the back surface electrode type solar battery cell  5  in  FIG. 1 , i.e. even if a portion where the electrode is exposed appears, the insulating protective film  2  provided between the portion where the electrode is exposed and the module wiring  23  prevents the portion where the electrode is exposed and, the module wiring  23  from touching with each other improperly. Similarly, the insulating protective film  2  prevents the portion where the electrode is exposed and the module wiring  4   a  and  4   b  from touching with each other improperly. 
     The portion indicated by an arrow in  FIG. 1  indicates a portion where the positive electrode  16  and the module wiring  4   a  are adjacent to each other and a portion where the negative electrode  17  and the module wiring  4   b  are adjacent to each other. 
     Consequently, on the solar battery module substrate  1 , a cell distance D 1  between the two back surface electrode type solar battery cells  5  can be shorter than the cell distance D 111 ′ ( FIG. 17 ) on the solar battery module substrate  112 . Further, the solar battery module  7  having the solar battery module substrate  1  can output an electromotive force corresponding to its size. Further, the solar battery module  7  can fully exhibit a characteristic that the back surface electrode type solar battery cell  5  does not suffer from a drop in optical power generation performance. 
       FIG. 8  is a cross sectional drawing taken in line A-B of the solar battery module substrate  1  shown in  FIG. 1 . As shown in  FIG. 8 , the solar battery module substrate of the present embodiment may be provided with an insulating protective film  2   a  (a second insulating protective film) indicated by a shaded area. This configuration will be explained here with reference to a plane drawing of  FIG. 9 . 
       FIG. 9  is a plane drawing showing a solar battery module substrate  31  which is another solar battery module substrate of the present embodiment. The solar battery module substrate  31  is different from the solar battery module substrate  1  of  FIG. 1  in terms of an insulating protective film and an opening. 
     On the solar battery module substrate  31 , the insulating protective film  2  has a plurality of openings  32   o  smaller than the opening  2   o  of  FIG. 1 . Each opening  32   o  (first opening and second opening) exposes only one cathode mounting terminal  3   a  or only one anode mounting terminal  3   b . The insulating protective film  2   a  is provided between two adjacent openings  32   o . That is, the opening  32   o  and the insulating protective film  2   a  are provided alternately. 
     The solar battery module substrate  31  includes the insulating protective film  2  having at least one opening  32   o . This allows electrical connection between the back surface electrode type solar battery cell  5  and the conductive pattern. Further, even if a part of an electrode of the back surface electrode type solar battery cell  5  (a part of the positive electrode  16  or a part of the negative electrode  17 ) is exposed at a portion indicated by an arrow of an edge T of the back surface electrode type solar battery cell  5  in  FIG. 1 , i.e. even if a portion where the electrode is exposed appears, the insulating protective film  2  provided between the portion where the electrode is exposed and the module wiring  23  prevents the portion where the electrode is exposed and the module wiring  23  from touching with each other improperly. Similarly, the insulating protective film  2  prevents the portion where the electrode is exposed and the module wiring  4   a  and  4   b  from touching with each other improperly. 
     The portion indicated by an arrow in  FIG. 1  indicates a portion where the positive electrode  16  and the module wiring  4   a  are adjacent to each other and a portion where the negative electrode  17  and the module wiring  4   b  are adjacent to each other. 
     Consequently, on the solar battery module substrate  31 , a cell distance D 1  between the two back surface electrode type solar battery cells  5  can be shorter than the cell distance D 111 ′ ( FIG. 17 ) on the solar battery module substrate  112 . Further, the solar battery module having the solar battery module substrate  31  can output an electromotive force corresponding to its size. Further, the solar battery module having the solar battery module substrate  31  can fully exhibit a characteristic that the back surface electrode type solar battery cell  5  does not suffer from a drop in optical power generation performance. 
     On the solar battery module substrate  31 , provision of the opening  32   o  and the insulating protective film  2   a  allows the cathode mounting terminal  3   a  and the anode mounting terminal  3   b  to be more surely insulated from each other in electrical connection between the back surface electrode type solar battery cell  5  and the conductive pattern. Further, provision of the insulating protective film  2   a  allows dispersing a strength applied on the solar battery module substrate  31  in mounting the back surface electrode type solar battery cell  5  on the solar battery module substrate  31 , and allows smoother sealing by the transparent protective resin  6 . 
       FIG. 10  is a plane drawing showing a solar battery module  41  which is still another solar battery module of the present embodiment. (a) of  FIG. 10  is a plane drawing showing a front surface of the solar battery module  41 . (b) of  FIG. 10  shows a plane drawing showing a back surface of the solar battery module  41 . 
     As shown in (a) of  FIG. 10 , in the solar battery module  41 , ten back surface electrode type solar battery cells  5  are connected with each other in series. Further, an edge of the module wiring  4   a  is connected with the back surface electrode type solar battery cell  5 . Further, an edge of the module wiring  4   b  is connected with the back surface electrode type solar battery cell  5 . Further, the other edge (i.e. an edge which is not connected with the back surface electrode type solar battery cell  5 ) of the module wiring  4   a  is provided with a via  42  which penetrates the solar battery module  41  to the back surface thereof. Further, the other edge (i.e. an edge which is not connected with the back surface electrode type solar battery cell  5 ) of the module wiring  4   b  is provided with a via  43  which penetrates the solar battery module  41  to the back surface thereof. 
     Further, as shown in (b) of  FIG. 10 , the via  42  is connected with (i) a mounting electrode  44   a  connected with an electrode of a mounting substrate (not shown) on which the solar battery module  41  is mounted and (ii) a test pad  45   a . The via  43  is connected with (i) a mounting electrode  44   b  connected with an electrode of the mounting substrate and (ii) a test pad  45   b.    
     The module wiring  4   a  and  4   b  and the mounting electrodes  44   a  and  44   b  allow the solar battery module  41 , and the mounting substrate to be electrically connected with each other. 
     In the above explanation, the back surface electrode type solar battery cell  5  is designed such that the positive electrodes  16  and the negative electrodes  17  are positioned alternately. Alternatively, a back surface electrode type solar battery cell  5 ′ (solar battery cell) in which the positive electrodes  46  and the negative electrodes  47  are positioned in a checkered pattern may be used. In other words, this positioning of electrodes is such that both in two different directions (longitudinal and lateral directions in  FIG. 11 ), at least one positive electrode  46  and at least one negative electrode  47  are provided in such a manner that electrodes of the same polarity are not adjacent to each other. The shapes of the positive electrode  46  and the negative electrode  47  are rectangular parallelepiped for example. 
     A broken line in  FIG. 11  indicates an outline of an opening  2   o  of the insulating protective film  2  on a solar battery module substrate on which the back surface electrode type solar battery cell  5 ′ is mounted. The outline of the opening  2   o  is positioned inside an outline  48  of the back surface electrode type solar battery cell  5 ′, and the outline  48  constitutes a projected portion when the back surface electrode type solar battery cell  5 ′ is mounted on the solar battery module substrate. 
     The solar battery module substrate on which the back surface electrode type solar battery cell  5 ′ is mounted includes an insulating protective film, a positive electrode mounting terminal, a negative electrode mounting terminal, module wiring connected with the positive electrode mounting terminal, and module wiring connected with the negative electrode mounting terminal, as in the case of the solar battery module substrate  1 . The insulating protective film has an opening for exposing the positive electrode mounting terminal and the negative electrode mounting terminal. The opening is positioned to be inside the projected portion of the back surface electrode type solar battery cell  5 ′. 
     In the present embodiment, the number of solar battery cells to be connected with each other in series is not particularly limited. The two solar battery cells in  FIG. 1  and the ten solar battery cells in  FIG. 10  are merely examples. In general, an operating voltage of a logic IC is 5V, and an electromotive voltage per one cell is 0.5V. Accordingly, ten cells connected with each other in series allow an IC to operate. In this manner, the number of cells to be connected in series should be determined so that an operating voltage of a desired circuit can be obtained. 
     Further, in the solar battery modules  7  and  41 , by making the color of the insulating protective film  2  equal to that of the surface of the back surface electrode type solar battery cell  5 , the whole of the solar battery modules  7  and  41  have the color of the surface of the back surface electrode type solar battery cell  5 . This makes an influence on the design of a device on which the solar battery modules  7  and  41  are mounted as small as possible. 
     SUMMARY OF EMBODIMENTS 
     The solar battery module substrates  1 ,  22 , and  31  may be arranged such that the conductive pattern further includes the module wiring  4   a  and  4   b , and one edges of the module wiring  4   a  and  4   b  are connected with the cathode mounting terminal  3   a  and the anode mounting terminal  3   b , respectively, and the other edges of the module wiring  4   a  and  4   b  are respectively connected with mounting electrodes ( 44   a ,  44   b ) connected with an electrode of a mounting substrate on which a solar battery module is mounted. 
     This allows electrical connection between the solar battery module obtained by mounting the solar battery cell on the solar battery module substrates  1 ,  22 , and  31  and the mounting substrate. 
     The solar battery module  7  or  41  is obtained by mounting, on the solar battery module substrate  1 ,  22 , or  31 , at least two back surface electrode type solar battery cells  5  or at least two back surface electrode type solar battery cells  5 ′ on a back surface of which both of the cathode and the anode are provided. This allows the solar battery module  7  or  41  to fully exhibit a characteristic that the back surface electrode type solar battery cell  5  or  5 ′ does not suffer from a drop in optical power generation performance. 
     The solar battery modules  7  and  41  may be arranged such that at least a part of an electrode of the back surface electrode type solar battery cells  5  and  5 ′ is exposed at an edge of a cell. 
     Further, the solar battery modules  7  and  41  may be arranged such that at least one positive electrode  46  and at least one negative electrode  47  of the back surface electrode type solar battery cell  5 ′ are positioned in such a manner that electrodes of the same polarity are not adjacent to each other. 
     The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person within the scope of the claims. An embodiment based on a proper combination of technical means disclosed in different embodiments is encompassed in the technical scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     In the solar battery module substrate of the present invention, a portion where an electrode is exposed does not contact with its surrounding improperly. Accordingly, the solar battery module substrate is applicable to a relatively small solar battery module mounted on a portable phone. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  22 ,  31 : solar battery module substrate 
           2 : insulating protective film (insulating protective film, first insulating protective film) 
           2   a : insulating protective film (second insulating protective film) 
           2   o : opening (opening) 
           3   a ,  24 : cathode mounting terminal 
           3   b ,  25 : anode mounting terminal 
           4   a ,  4   b : module wiring 
           5 ,  5 ′: back surface electrode type solar battery cell (solar battery cell) 
           6 : Transparent protective resin 
           7 ,  41 : Solar battery module 
           12 : Surface 
           13 : Sun 
           14 : Incident light 
           15 : back surface 
           16 ,  46 : Positive electrode (cathode) 
           17 ,  47 : Negative electrode (anode) 
           18 : Electron-hole pair 
           19 : Electron 
           20 : Hole 
           21 : Back surface electrode type cell wafer for housing 
           23 : Module wiring (first module wiring) 
           26 : Solder paste 
           32   o : Opening (first opening, second opening) 
           42 ,  43 : Via 
           44   a ,  44   b : Mounting electrode 
           45   a ,  45   b : Test pad 
           48 : Outline 
         D 1 : Cell distance 
         T: edge (cell edge) 
         W 1 : Distance