Abstract:
There is provided a terminal box for solar cell module, capable of ensuring waterproofing capability and insulating capability without requiring separate members such as packings. The terminal box includes: a box main body to be attached to a solar cell module; a plurality of connection terminals arranged inside the box main body for connection to a plurality of end ribbons from solar cells in the solar cell module; external-connection cables each having an end which is connected to a corresponding one of the connection terminals, and another end which is pulled out of the box main body; and cable through-holes for routing the external-connection cables into the box main body. The box main body has resin pockets for a filler resin, at regions where the cables are inserted.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is based on International Application PCT/JP2011/051050 which claims priority on the basis of Japanese Patent Application No. 2010-017204. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a terminal box for solar cell module to be attached to a solar cell module for connecting the module with another solar cell module. The invention also relates to a solar cell module using the terminal box. 
       BACKGROUND ART 
       [0003]    Solar power generation systems are gathering attention in recent years as environmentally friendly power generation systems, from increasing awareness in environmental issues. One form of such solar power generation systems is a solar-light power-generation system which uses solar cell modules installed in a matrix pattern on a roof of a building for example. In such a solar power generation system, each solar cell module has a terminal box attached thereto, in order to provide electrical connection to adjacent solar cell modules as well as to extract electrical power which is generated by each solar cell module (see Patent Literature 1). 
         [0004]    The terminal box for solar cell module includes a box main body which has a plurality of terminals inside the box main body, for electrical connection to output terminals of the solar cell modules. Each of these terminals is electrically connected to an end of an external-connection cable, with the other end of the cable being connected to a cable from another terminal box for solar cell module for example. 
         [0005]    In the above-described conventional terminal box for solar cell module, insulating resin such as silicone resin is used as a sealing resin to fill inside of the box main body to ensure waterproofing capability and insulating capability of the terminal box for solar cell module. 
       CITATION LIST 
     Patent Literature 
       [0006]    [Patent Literature 1] JP-A 2001-77391 Gazette 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    The above-described external-connection cables have an outer coat which is made of insulating resin such as cross-linked polyethylene. However, the outer coat of the external-connection cable and silicone resin, for example, are not bonded strongly enough to each other and further, small gaps between the cable and the surrounds are not filled completely with silicone resin. Therefore, the terminal box cannot maintain its waterproofing function to a sufficient level, and the terminal box is subject to such troubles as water finding its way into the terminal box. 
         [0008]    In order to prevent the water troubles, members such as packings and O rings are sometimes attached to the cable. However, these solutions have problems, including that it requires separate members such as packings; that it requires additional steps of assembly; and that it increases cost. 
         [0009]    An object of the present invention is to provide a terminal box for solar cell module capable of ensuring waterproofing capability and insulating capability without requiring separate members such as packings. 
       Solution to Problem 
       [0010]    The present invention provides a terminal box for a solar cell module, which includes: a box main body to be attached to the solar cell module; a plurality of connection terminals arranged inside the box main body for connection to a plurality of end ribbons from solar cells in the solar cell module; external-connection cables each having an end which is connected to a corresponding one of the connection terminals and another end which is drawn out of the box main body; and cable through-holes in the box main body for routing the external-connection cables into the box main body. With this arrangement, the box main body has a resin pocket for a filler resin, at a region where the external-connection cable is inserted. 
         [0011]    The resin pocket may be made inside the cable through-hole. 
         [0012]    Also, the resin pocket may be made near a connection area between the cable through-hole and an inside of the box main body. 
         [0013]    A solar cell module according to the present invention includes: a front surface member; a rear surface member; a plurality of solar cells disposed between the front surface member and the rear surface member; a sealing member sealing the solar cells between the front surface member and the rear surface member; and the-above described terminal box for solar cell module, attached to the rear surface member. 
       Advantageous Effects of Invention 
       [0014]    The present invention includes a resin pocket for a filler resin, at a region where the external-connection cable is inserted. This ensures that the filler resin fills completely, thereby preventing water, for example, from finding its way into the through-hole. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a plan view which shows a solar cell module with a terminal box according to the present invention attached thereto. 
           [0016]      FIG. 2  is a plan view which shows a primary portion of a solar cell panel to which the terminal box according to the present invention is attached. 
           [0017]      FIG. 3  is a side view of a terminal box for solar cell module according to a first embodiment of the present invention, with half of the side shown in a sectional view. 
           [0018]      FIG. 4  is a plan view of the terminal box for solar cell module according to the first embodiment of the present invention, showing a state where its lid portion is removed, with part of a cable through-hole shown in a sectional view. 
           [0019]      FIG. 5  is a side view of a terminal box for solar cell module according to a second embodiment of the present invention, with half of the side shown in a sectional view. 
           [0020]      FIG. 6  is a side view of a variation of the terminal box for solar cell module according to the second embodiment of the present invention, with half of the side shown in a sectional view. 
           [0021]      FIG. 7  is a side view of a terminal box for solar cell module according to a third embodiment of the present invention, with half of the side shown in a section. 
           [0022]      FIG. 8  is a plan view of the terminal box for solar cell module according to the third embodiment of the present invention, showing a state where its lid portion is removed. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]    Embodiments of the present invention will be described in detail with reference to the drawings. It should be noted here that throughout the drawings the same or equivalent parts and components will be indicated with the same reference symbols, and in order to avoid redundancy in description, their description will not be repeated. 
         [0024]    First, a solar cell module to which a terminal box according to the present invention is attached will be described with reference to  FIG. 1  and  FIG. 2 .  FIG. 1  is a plan view which shows a solar cell module with a terminal box according to the present invention attached thereto.  FIG. 2  is a plan view which shows a primary portion of a solar cell panel to which the terminal box according to the present invention is attached. 
         [0025]    A solar cell module  1  to which a terminal box according to the present invention is attached includes a solar cell panel  10  which has a plurality of solar cells  11  . . . therein; and a frame  20  attached therearound. Each solar cell  11  is made of crystalline semiconductors provided by monocrystal silicon and polycrystal silicon having a thickness of 0.15 mm for example in a substantially square shape having a side of 100 mm approx. However, the present invention is not limited to this, and the solar cells may be of a different type. 
         [0026]    The solar cell  11  has, for example, an n-type region and a p-type region formed therein. A junction is formed in the interface between the n-type region and the p-type region, for formation of an electric field to separate carriers. The solar cell used in this embodiment may have an arrangement, for example, that a substantially intrinsic amorphous silicon layer is placed between a monocrystal silicon substrate and an amorphous silicon layer for reduced defect in the interface therebetween and improved characteristics of a hetero junction interface. 
         [0027]    Each of these solar cells  11  is electrically connected with the adjacent solar cells  11  with ribbons  102  which are made of flat copper foils for example. Specifically, each ribbon has its first-end side connected to an upper surface side electrode of a certain solar cell  11  while its second-end side is connected to a lower surface side electrode of another solar cell  11  adjoining the certain solar cell. These solar cells  11  . . . are connected in series by the ribbons  102 , to form a string  110 , and these strings  110 ,  110  are connected with each other by bus ribbons  111 . Also, the strings  110  are connected to end ribbons  112 , so that a predetermined level of output, of  200  Watts for example, is drawn from the solar cell module  1  via the end ribbons  112 . Also, the solar cell panel  10  includes a plurality of solar cells  11  sealed between a transparent front surface member such as glass or transparent plastic and a rear surface member which is provided by a weather resistant film as a weather resistance member, made by sandwiching a metal foil on the rear side between insulating films, or a transparent member such as glass or transparent plastic, using a sealing member  14  which has good weather resistance and moisture resistance such as EVA (ethylene vinyl acetate). 
         [0028]    As shown in  FIG. 1  and  FIG. 2 , the terminal box  30  is attached to the rear surface member, near the frame  20  of the solar cell panel  10 , using an adhesive or the like. 
         [0029]      FIG. 2  shows the terminal box  30  in a simplified manner without details of the terminals, etc. The terminal box  30  includes a box main body  31  having therein connection terminals  33   a  through  33   e  provided correspondingly to the end ribbons from the solar cell panel  10 . Correspondingly to these connection terminals  33   a  through  33   e , ribbon holes  38  . . . are formed in a bottom of the box main body  31  for insertion of the end ribbons. Also, through-holes (unillustrated) are formed on two side surfaces of the box main body  31  for insertion of external-connection cables  17 . 
         [0030]    In the embodiment in  FIG. 2 , five connection terminals are provided for four end ribbons  112  . . . In this embodiment, the end ribbons are not connected to the connection terminals  33   c , so the connection terminals  33   c  and the connection terminals  33   d  are connected with each other with a jumper wire  35 . A bypass diode  34  is connected at each of the following places; across the connection terminals  33   a  and  33   b , across the connection terminals  33   b  and  33   c , and across the connection terminals  33   d  and  33   e.    
         [0031]    With the above, connection between the terminal box  30  and the end ribbons  112  from the solar cell panel  10  is made as follows: Through the ribbon holes  38  . . . , the end ribbons  112  . . . are introduced inside, and each of the end ribbons  112  . . . is soldered to one of the connection terminals  33   a ,  33   b ,  33   d ,  33   e . Then, the cables  17  inserted into the connection terminal  33   a  via the through-holes are rigidly fixed by cable swaging for example. Likewise, the cables  17  inserted into the connection terminal  33   e  via the through-hole are rigidly fixed by cable swaging for example. 
         [0032]    Following these steps, the end ribbons  112  from the solar cell panel  10  are connected in series by using the terminal box  30 , so that a cable  17  for a positive terminal and a cable  17  for a negative terminal are drawn out of the terminal box  30 . 
         [0033]    Next, a terminal box for solar cell module according to a first embodiment of the present invention will be described with reference to  FIG. 3  and  FIG. 4 .  FIG. 3  is a side view of a terminal box for solar cell module according to the first embodiment of the present invention, with half of the side shown in a sectional view whereas  FIG. 4  is a plan view of the terminal box, showing a state where its lid portion is removed, with part of a cable through-hole shown as a sectional view. 
         [0034]    Like the example described thus far, this terminal box  30  for solar cell module according to the first embodiment is attached to a rear surface of a solar cell panel  10  which includes a plurality of solar cells connected electrically in series. 
         [0035]    The terminal box  30  is made of a synthetic resin by molding for example, and includes a box main body  31  which has a holding recess  37  inside itself, and a platy lid member  32  which closes the holding recess  37 . The box main body  31  is structured as a rectangular case with its upper surface open to the outside. The lid member  32  is attached on the upper surface side of the box main body  31 . 
         [0036]    The terminal box  30  is attached by bonding the lower surface of the box main body  31  to the rear surface member of the solar cell panel  10  by using an adhesive. Also, for purposes of waterproofing, moisture prevention, heat dissipation, water condensation prevention, etc., silicone resin is used to fill the holding recess  37  as a filler resin, and then the lid member  32  is fitted securely. 
         [0037]    The box main body  31  has a bottom formed with the ribbon holes  38  through which the end ribbons from the solar cell panel  10  are inserted. Also, cable through-holes  36  are formed on left and right ends of the box main body  31  for insertion of external-connection cables  17 . 
         [0038]    Also, connection terminals  33   a  through  33   e  are erected side by side in the left-right direction from the bottom surface, correspondingly to the ribbon holes  38 , between the cable through-hole  36 ,  36  in the box main body  31 . In this embodiment, connection of the cables  17  are made by, first, fitting core wire portions  17   b  of the cables  17  into connection portions of the respective left and right connection terminals  33   a ,  33   e  and then tightly fixing the portions. 
         [0039]    With the above, edge portions of the plural end ribbons from the solar cell panel  10  are inserted into the box main body  31  through the ribbon holes  38 , and then soldered to edge portions of the respective connection terminals  33   a  through  33   e.    
         [0040]    Also, between mutually adjacent connection terminals  33   a  through  33   e , metal heat dissipation plates  35  . . . are formed so as to connect with the connection terminals. Bypass diodes  34  each working as a rectifier for a bypass are disposed across two metal heat dissipation plates  35 . These bypass diodes  34  are connected across the connection terminal. 
         [0041]    Heat generated in the bypass diodes  34  is dissipated through the heat dissipation plates  35 , so the arrangement can effectively prevent localized hot spots. The heat dissipation plates  35  provide heat removal from increased area, achieving improvement in heat dissipation capabilities. This improves durability of the bypass diodes  34 , etc., offering an advantage of improved long term reliability of the bypass diodes  34 , and of the solar cell module in this regard. 
         [0042]    The cables  17  are inserted through the through-holes  36  and then into the box main body  31 . Then, the cables  17  are fixed to the box main body  31  of the terminal box  30  with unillustrated cable fasteners. 
         [0043]    The cables  17  have an outer coat  17   a  made of cross-linked polyethylene, for example. Cross-linked polyethylene does not provide good bonding to silicone resin and in addition does not easily find its way into narrow gaps. To improve on these, silicone pockets  37   a  are provided inside the through-holes  36  in the present embodiment to ensure that silicone resin will fill sufficiently. Specifically, in this first embodiment, the through-holes  36  are given a sufficiently larger inner diameter than an outer diameter of the cables  17 , to form the silicone pockets  37   a  so that silicone resin will flow from the holding recess  37  of the box main body  31  and fill the space. 
         [0044]    With this arrangement, the core wire portions  17   a  of the cables  17  are first connected to the connection terminals  33   a  ( 33   e ). Subsequently, the holding recess  37  of the box main body  31  is filled with silicone resin. The silicone resin flows between the through-hole  36  and the outer coat  17   a  of the cable  17 , and fills the silicone pockets  37   a  sufficiently. As a result, gaps between the through-hole  36  and the cable  17  are filled with silicone resin, reliably preventing entry of water etc. from the through-holes  36 . 
         [0045]    Next, a second embodiment of the present invention will be described with reference to  FIG. 5 .  FIG. 5  is a side view of a terminal box for solar cell module according to the second embodiment of the present invention, with half of the side shown in a sectional view. It should be noted here that the same or equivalent parts and components as in the first embodiment will be indicated with the same reference symbols, and in order to avoid redundancy, their description will not be repeated hereafter. 
         [0046]    While the silicone pocket  37   a  is formed inside the through-hole  36  according to the first embodiment, a silicone pocket  37   b  in the second embodiment is formed near the connection area between the through-hole  36  for the cable  17  and inside (the holding recess  37 ) of the box main body  31 . The silicone pocket  37   b  is formed by enlarging a lower region of the box main body  31  which faces the through-hole  36  of the box main body  31 . The silicone pocket  37   b  ensures that the inside space of the box main body  31  facing the through-hole  36  is sufficiently filled with silicone resin. Since silicon resin reliably fills the spaces where the cables  17  are inserted into the box main body  31 , the arrangement reliably prevents water which happens to find its way from any gap between the through-holes  36  and the cables  17 , by the silicone resin which completely fills up the silicone pocket  37   b.    
         [0047]    It should be noted here that in the second embodiment described above, the through-hole  36  has a slightly greater inner diameter than an outer diameter of the cables  17 . However, as shown in a variation of the second embodiment in  FIG. 6 , a silicone pocket  17   a  may be provided inside the through-hole  36 . The combination of the silicone pocket  37   a  inside the through-hole  36  and the silicone pocket  37   b  inside the box main body  31  enhances waterproofing capability. 
         [0048]    Next, a third embodiment of the present invention will be described with reference to  FIG. 7  and  FIG. 8 .  FIG. 7  is a side view of a terminal box for solar cell module according to the third embodiment of the present invention, with half of the side shown in a sectional view.  FIG. 8  is a plan view of the terminal box, showing a state where its lid portion is removed, with part of a cable through-hole shown in a sectional view. The same or equivalent parts and components as in the first embodiment will be indicated with the same reference symbols, and in order to avoid redundancy, their description will not be repeated hereafter. 
         [0049]    While the silicone pocket  37   a  in the first embodiment is formed inside the through-hole  36  by enlarging the inner diameter of the through-hole  36 , the third embodiment uses an arrangement where the core wire portion  17   b  of the cable  17  comes inside the through-hole  36 , and a silicone pocket  37   c  is formed between the core wire portion  17   b  of the cable  17  and an inner wall of the through-hole  36 . In this third embodiment, the core wire portion  17   b  of the cable  17  makes contact with silicone resin inside the through-hole  36 . Bonding strength between the core wire portion  17   b  and silicone resin is better than that between the outer coat  17   a  of the cable  17  and silicone resin, and therefore the arrangement provides more improved waterproofing capability than the first and the second embodiments. 
         [0050]    It should be noted here that the quantity of the bypass diodes disposed, or the quantity and shape of the terminals disposed in each embodiment described thus far may be determined as appropriate. These do not limit any of the embodiments. 
         [0051]    All of the embodiments disclosed herein are to show examples, and should not be considered as of a limiting nature in any way. For example, the present invention is also applicable to thin-film solar cell modules. The scope of the present invention is identified by the claims and is not by the descriptions of the embodiments given hereabove, and it is intended that the scope includes all changes falling within equivalents in the meaning and extent of the Claims. 
       REFERENCE SIGNS LIST 
       [0052]      30  terminal box 
         [0053]      31  box main body 
         [0054]      32  lid portion 
         [0055]      33   a  through  33   e  connection terminals 
         [0056]      36  through-hole 
         [0057]      37  holding recess 
         [0058]      37   a ,  37   b ,  37   c  silicone pocket 
         [0059]      17  cable 
         [0060]      17   a  outer coat 
         [0061]      17   b  core wire portion