WO2011039951A1

WO2011039951A1 - Solar cell module

Info

Publication number: WO2011039951A1
Application number: PCT/JP2010/005521
Authority: WO
Inventors: Hiroshi Kubo
Original assignee: Fujifilm Corporation
Priority date: 2009-09-30
Filing date: 2010-09-09
Publication date: 2011-04-07
Also published as: TW201130146A; JP2011077301A

Abstract

A solar cell module includes a solar cell module body having a submodule provided with a photoelectric conversion unit having a function capable of obtaining electricity from light, and a positive electrode and a negative electrode, a first conductive member connected to the negative electrode of the photoelectric conversion unit, a second conductive member connected to the positive electrode of the photoelectric conversion unit, and a connection box connected to the first conductive member and the second conductive member. The connection box is provided inside the solar cell module body and has a thickness substantially equal to that of the solar cell module body.

Description

SOLAR CELL MODULE

The present invention relates to a thin solar cell module of thin-film type and particularly to a solar cell module having an even thickness without projections or the like.

Today, intensive researches are being conducted in solar cells. Solar cell modules forming a solar battery each comprise on a substrate a solar cell submodule including a number of series-connected laminate-structured photoelectric conversion elements essentially composed of photoelectric conversion layers generating current by light absorption each sandwiched by a back electrode (lower electrode) and a transparent electrode (upper electrode). There have been heretofore proposed various solar cell submodules.

As illustrated in Fig. 5, a solar cell module 100 has a glass substrate 104 provided on the underside of a solar cell submodule 102 and a cover glass 108 secured to the opposite side from the glass substrate 104 of the solar submodule 102 by an EVA resin layer (ethylene vinyl acetate resin layer) 106 serving as bond/seal layer. On the underside of the glass substrate 104 is secured a back sheet 110 by another EVA resin layer 106.

The back sheet 110 has attached thereto a connection box 112 to which the line led from the solar cell submodule 102 is connected. The connection box 112 is equipped with a cable 114 through which the solar cell module 100 can be connected to the outside.
The solar cell submodule 102 and the glass substrate 104 with the cover glass 108 and the back sheet 110 attached are secured to a frame 118 through the intermediary of a seal material 116.
A variation of the solar cell module 100 is not provided with the glass substrate 104; still another variation thereof has a protection layer in lieu of the cover glass 108.

The solar cell module 100 is manufactured for example as illustrated in Figs 6A to 6D.
First, to be provided is the solar cell submodule 102 as illustrated in Fig. 6A comprising on the surface of a substrate a number of series-connected laminate-structure photoelectric conversion elements each formed of a semiconductor photoelectric conversion layer generating current by light absorption sandwiched by an underside electrode and a transparent electrode.
Next, as illustrated in Fig. 6B, lines 120 using copper foil, for example, are provided at the electrode terminals of both end portions of the solar cell submodule 102. Then, lines 122 are provided so as to extend from the lines 120 located at both ends and fold back onto an underside 102b of the solar cell submodule 102 to reach a substantially central portion of the solar cell submodule 102. The wiring lines 122 are formed, for example, of copper ribbon.

Next, as illustrated in Fig. 6C, the EVA resin layer 106 and a cover layer 124 are provided on a top side 102a of the solar cell submodule, and the EVA resin layer 106 and the back sheet 110 are provided on a bottom side 102b of the solar cell submodule 102. The lines 122 project through holes (not shown) made in the EVA resin layer 106 and the back sheet 110 provided on the bottom side. Now, these are integrated by a vacuum laminating method.
Subsequently follows trimming, then the procedure proceeding to fold back the lines 122 projecting from the back sheet 110 or taking other steps as may be required so that the lines 122 are connected, as illustrated in Fig. 6D, to the terminal box 112, thereafter securing the terminal box 112 to the back sheet 110 with an adhesive other means.

There are proposed various other solar cell submodules than that described above (see Patent Documents 1 and 2).
The solar cell module described in Patent Document 1 has a solar battery disposed on a top surface protection member formed of FTFE (ethylene tetrafluoroethylene) and an adhesive resin formed of EVA (ethylene vinyl acetate) superposed on each other. The solar battery is equipped with a terminal connected by soldering to a lead wire to collect generated electricity. Thereon is provided another adhesive resin formed of EVA and a notched copper plate as the bottom surface protection member.
The lead wire is led past a lateral side of the bottom surface protection member through the notch of the bottom surface protection member to reach the non-light receiving surface of the bottom surface protection member. The lead wire led onto the non-light receiving surface of the bottom surface protection member is routed into the terminal box provided on the non-light receiving surface of the bottom surface protection member to output generated electricity to the outside. Thus, the solar cell module described in the Patent Document 1 also has the terminal box positioned on the bottom side thereof.

The solar cell module described in the Patent Document 2 has an internal cable for delivering the electricity generated by the solar cell module to a terminal and another cable for collecting generated electricity on the outside, the lead wire and the cable being connected by soldering at a connection portion on a bottom side reinforcement plate. The cable is secured by resin formed into a cylinder provided on the surface of the bottom side reinforcement plate. This resin acts as the terminal in the solar cell module described in the Patent Document 2. Thus, a constituent part acting as a terminal in the solar cell module described in the Patent Document 2 is also positioned on the bottom side thereof.

JP 3972245 B JP 2006-210446 A

TECHNICAL PROBLEMS

Solar cell submodules are thin and therefore solar cell modules should also permit reduction of their thickness. However, in the conventional solar cell module 100, the connection box is provided close to the center of the back sheet 110, increasing the thickness of the solar cell module 100 and making the thickness uneven, with the connection box projecting from the surface.
With the modules described in the Patent Documents 1 and 2, the terminal box and the terminals are provided on the underside of the solar cell module, which increases the thickness of the solar cell modules and results in an uneven thickness thereof because the terminal box and the terminals project from the surface.
Thus, transporting conventional solar cell modules stacked on each other required a spacer having a recess for accommodating the connection box, etc. and other like jigs, which increased the transportation costs.

In addition, the connection box and the like of the solar cell modules impeded the installation work and made handling difficult, resulting in increased installation costs. Further, the connection box, etc. could break upon impact and thus reduce the reliability of the solar cell modules.
Thus, conventional solar cell modules required high transportation costs and installation costs, which could increase the costs of the solar cell modules.

An object of the present invention is to overcome the above problems associated with the prior art and provide a solar cell module having no projections or the like and a uniform thickness.

SOLUTION TO THE PROBLEMS

To achieve the above objects, the invention provides a solar cell module comprising a solar cell module body including a submodule provided with a photoelectric conversion unit having a function capable of obtaining electricity from light, and a positive electrode and a negative electrode, a first conductive member connected to the negative electrode of the photoelectric conversion unit, a second conductive member connected to the positive electrode of the photoelectric conversion unit, and a connection box connected to the first conductive member and the second conductive member, wherein the connection box is provided inside the solar cell module body and has a thickness substantially equal to that of the solar cell module body.

The connection box is preferably provided in a region that is formed by cutting out a part of the solar cell module body.
The first conductive member and the second conductive member are preferably connected to the connection box without being bent.
Preferably, the first conductive member and the second conductive member are arranged substantially linearly at one end portion of the submodule and connected to the connection box in a manner kept substantially linear.
Preferably, the submodule further comprises a substrate used as a conductor and provided with the photoelectric conversion unit, the positive electrode is positioned at one end portion of the photoelectric conversion unit and the negative electrode is positioned at another end portion of the photoelectric conversion unit, and wherein the substrate is connected to one of the positive electrode and the negative electrode, and the first conductive member or the second conductive member is provided on the substrate at an end of the substrate that is not connected to the one of the negative electrode and the positive electrode.

Preferably, the substrate has a conductive portion and an insulation layer formed on at least one side of the conductive portion, and the photoelectric conversion unit is formed on the insulation layer, the conductive portion of the substrate is used as the conductor and connected to the one of the positive electrode and the negative electrode, and the first conductive member or the second conductive member is provided on the conductive portion of the substrate at an end of the conductive portion that is not connected to the one of the negative electrode and the positive electrode.
The insulation layer is preferably formed of anodized aluminum.

The submodule is preferably a thin-film solar cell submodule.
The submodule is preferably an integrated type thin-film solar cell submodule.
The submodule is preferably a grid type solar cell submodule.

Further, the photoelectric conversion unit preferably comprises one kind of thin-film solar cells selected from the group consisting of CIS based thin-film solar cells, CIGS based thin-film solar cells, thin-film silicon-based thin-film solar cells, CdTe based thin-film solar cells, III-V group based thin-film solar cells, dye-sensitized thin-film solar cells, and organic thin-film solar cells.

According to the solar cell module of the invention, the connection box is mounted inside the solar cell module body, and the connection box has substantially the same thickness as the solar cell module body such that the solar cell module body has no projections from the surface. Accordingly, the work efficiency in transportation and installation of the solar cell module increases. Thus, although transporting conventional solar cell modules stacked on each other required a spacer having a recess for accommodating the connection box, etc. and other like jigs, the solar cell module of the invention requires no such spacers or other like jigs. Thus, transportation costs can be reduced.

Further, the solar cell module of the invention, having no projections, permits easy handling and hence increased work efficiency, which in turn reduces installation costs. Still further, since the connection box of the solar cell module of the invention does not have a chance of breaking upon impact, the reliability of the solar cell module increases. Thus, the transportation costs and installation costs can be reduced, as well as the costs of the solar cell module.

Fig. 1 is an enlarged cross section schematically illustrating how a connection box is disposed in a solar cell module according to a first embodiment of the invention. Fig. 2A is a top plan view of a solar cell submodule of the solar cell submodule according to the first embodiment of the invention. Fig. 2B is a top plan view schematically illustrating how the connection box is disposed in the solar cell module according to the first embodiment of the invention. Fig. 2C is a lateral view schematically illustrating the thicknesses of the solar cell module according to the first embodiment of the invention and the connection box. Fig. 3 is a cross section schematically illustrating the solar cell submodule of the solar cell module according to the first embodiment of the invention. Fig. 4A is a top plan view of a solar cell submodule of the solar cell submodule according to a second embodiment of the invention. Fig. 4B is an enlarged cross section schematically illustrating how the connection box is disposed in the solar cell module according to the second embodiment of the invention. Fig. 4C is a schematic view illustrating the thicknesses of the solar cell module according to the second embodiment of the invention and the connection box. Fig. 5 is a schematic cross section illustrating a conventional solar cell module. Fig. 6A is a schematic view illustrating one of the steps of a method of manufacturing a conventional solar cell module in sequential order. Fig. 6B is a schematic view illustrating next one of the steps of a method of manufacturing a conventional solar cell module in sequential order. Fig. 6C is a schematic view illustrating next one of the steps of a method of manufacturing a conventional solar cell module in sequential order. Fig. 6D is a schematic view illustrating next one of the steps of a method of manufacturing a conventional solar cell module in sequential order.

The solar cell module of the invention will be described below based on preferred embodiments illustrated in the attached drawings.
Fig. 1 is an enlarged cross section schematically illustrating how a connection box is disposed in a solar cell module according to a first embodiment of the invention. Fig. 2A is a top plan view of a solar cell submodule of the solar cell submodule according to the first embodiment of the invention; Fig. 2B is a top plan view schematically illustrating how the connection box is disposed in the solar cell module according to the first embodiment of the invention; and Fig. 2C is a lateral view schematically illustrating the thicknesses of the solar cell module according to the first embodiment of the invention and the connection box. Fig. 1 is a cross section schematically illustrating the solar cell submodule of the solar cell module according to the first embodiment of the invention.

As illustrated in Fig. 1, a solar cell module 10 according to the first embodiment of the invention comprises a solar cell submodule 12, a bond/seal layer 14 and a top surface protection layer (which corresponds to a protection layer according to the invention) 16 provided on the top side of the solar cell submodule 12, a bond/seal layer 18 and a back sheet (which corresponds to a protection layer according to the invention) 20 provided on the bottom side of the solar cell submodule 12, and a connection box 22.
The top side of the solar cell submodule 12 denotes the side for receiving light for obtaining electricity; the bottom side denotes the opposite side from the top side.

The solar cell submodule 12, the bond/seal layer 14 and the top surface protection layer 16 provided on the top side of the solar cell submodule 12, the bond/seal layer 18 and the back sheet 20 provided on the bottom side of the solar cell submodule 12 are integrated with the solar cell submodule by vacuum laminating treatment according to a vacuum laminating technique. In this embodiment, the solar cell submodule 12, the bond/seal layer 14, the top surface protection layer 16, the bond/seal layer 18, and the back sheet 20 are referred to herein as a whole as a solar cell module body 10a. The solar cell module body 10a and the connection box 22 attached thereto constitute the solar cell module 10.

The solar cell submodule 12 comprises a photoelectric conversion unit 48 (see Fig. 2A) capable of obtaining electricity from light. The solar cell submodule 12 will be described in detail later.

The bond/seal layer 14 is provided to seal and protect the solar cell submodule 12 and bond it to the top surface protection layer 16.
The bond/seal layer 14 is formed, for example, of EVA (ethylene vinyl acetate) or PVB (polyvinylbutyral).

The top surface protection layer 16 is provided to protect the solar cell submodule 12 from smear, moisture, etc. and minimize the decrease of the amount of incoming light into the solar cell submodule 12 due to smear. The top surface protection layer 16 is formed, for example, of a fluorinated resin film. The fluorinated resin used is, for example, EFTE (ethylene/tetrafluoroethylene copolymer). The top surface protection layer 16 has a thickness of say 20 micrometers to 200 micrometers.

A water vapor barrier layer, for example, may be provided between the bond/seal layer 14 and the top surface protection layer 16. The water vapor barrier layer is provided to protect the solar cell submodule 12 from moisture. The water vapor barrier layer is formed of a transparent film made of, for example, PET or PEN, having an inorganic layer of, for example, SiO₂ or SiN formed thereon, or is formed of an inorganic layer made of, for example, SiO₂ or SiN sandwiched by transparent films made of, for example, PET or PEN.
The water vapor barrier layer is not specifically limited in composition, provided that it meets given performance requirements such as moisture vapor transmission rate, oxygen transmission rate, etc.

The bond/seal layer 18 provided on the bottom side of the solar cell submodule 12 has the same composition as the bond/seal layer 14 provided on the top side and will not be described in detail.
The back sheet 20 is provided to protect the solar cell module 10 from under the bottom side thereof and secure insulation of the solar cell module 10. The back sheet 20 has a structure such that, for example, an aluminum foil is sandwiched by resin films of PET, PEN, or the like. The back sheet 20 is not specifically limited in composition.

The connection box 22 is provided to collect the electricity obtained at the photoelectric conversion unit 48 of the solar cell submodule 12 onto the outside of the solar cell module 10 and connect a first conductive member 50 and a second conductive member 52 to

cables

66, 68, which in turn are connected to an external device (not shown) or another solar cell module. The connection box 22 will be described in detail later.

Next, the solar cell submodule 12 according to this embodiment will be described.
As illustrated in Fig. 2A, the solar cell submodule 12 according to this embodiment is rectangular as a whole and has the photoelectric conversion unit 48 formed on a rectangular metal substrate 30.
As illustrated in Fig. 30, the metal substrate 30 has, for example, a core material made of a stainless steel plate (which corresponds to a conductive portion in the invention) 32 provided with aluminum layers (which correspond to conductive portions in the invention) 34, 35 on its top surface 32a and bottom surface 32b, respectively. Thus, the top and bottom sides of the metal substrate 30 have surfaces formed of the aluminum layers 34, 35, respectively.
The aluminum layers 34, 35 of the metal substrate 30 are provided respectively with

insulation layers

36, 37. The insulation layer 36 is not formed at

end portions

34a, 34b of the aluminum layer 34 provided on the top side. The insulation layer 37 is also not formed on either of

end portions

35a, 35b of the aluminum layer 35 provided on the bottom side.

Such regions without the insulation layers 36, 37 may be secured by first forming the insulation layers 36, 37, and subsequently removing the corresponding portions of the insulation layers 36, 37 by, say, laser scribing.
Alternatively, where the insulation layers 36, 37 are formed by anodization, the regions without the insulation layers 36, 37 may be secured by masking both end portions and the lateral portions of the metal substrate 30.
On a surface 36a of the insulation layer 36 are formed, for example, series-connected photoelectric conversion elements (solar cells) 46 according to this embodiment, as will be described. The series-connected photoelectric conversion elements 46 constitute the photoelectric conversion unit 48.

The solar cell submodule 12 illustrated in Fig. 3 is of a substrate type, wherein the photoelectric conversion elements 46 provided in the solar cell submodule 12 as will be described are of a thin film type. The solar cell submodule 12 has thereon provided back electrodes 38, photoelectric conversion layers 40, buffer layers 42, and transparent electrodes 44 superposed on each other in this order; the back electrodes 38, the photoelectric conversion layers 40, the buffer layers 42, and the transparent electrodes 44 constitute the photoelectric conversion elements 46.

The back electrodes 38 are formed on the surface 36a of the insulation layer 36, and adjacent back electrodes 38 are separated each other by a separation groove (P1) 41. The photoelectric conversion layers 40 are formed on the back electrodes 38 so as to fill the separation grooves (P1) 41. The buffer layers 42 are formed on the surfaces of the photoelectric conversion layers 40. The photoelectric conversion layers 40 and the buffer layers 42 are separated from an adjacent photoelectric conversion layer 40 and an adjacent buffer layer 42 by grooves (P2) 43 reaching the back electrodes 38. The grooves (P2) 43 are formed in different positions from those of the separation grooves (P1) 41 separating the back electrodes 38.

The transparent electrodes 44 are formed on the surfaces of the buffer layers 42 so as to fill the grooves (P2) 43.
Opening grooves (P3) 45 are formed so as to reach the back electrodes 38 through the transparent electrodes 44, the buffer layers 42, and the photoelectric conversion layers 40. The photoelectric conversion elements 46 are connected in series to each other through the back electrodes 38 and the transparent electrodes 44. In this embodiment, the back electrode 39 disposed at the left end portion as seen in Fig. 1 is connected to the end portion 34b without the insulation layer 36 and thus electrically connected to the metal substrate 30.

The photoelectric conversion elements 46 of this embodiment are so-called integrated type CIGS photoelectric conversion elements (CIGS solar cells) and have a configuration such, for example, that the back electrodes 38 are molybdenum electrodes, the photoelectric conversion layers 40 are formed of CIGS, the buffer layers 42 are formed of CdS, and the transparent electrodes 44 are formed of ZnO.
As illustrated in Fig. 2A, the photoelectric conversion elements 30 are parallel to a side of the metal substrate 30 and extend in one direction. Accordingly, the back electrode 39, for example, is also longer in one direction parallel to the one side of the metal substrate 30.

As illustrated in Fig. 3, the first conductive member 50 is connected to a rightmost back electrode 38a. The first conductive member 50 is provided to collect the output from a negative electrode as will be described. Although a photoelectric conversion element 46 is formed on the back electrode 38a, that photoelectric conversion element 46 is removed by, say, laser scribing or mechanical scribing technique to expose the back electrode 38a.

The first conductive member 50 is, for example, an elongate strip member; it is connected to the back electrode 38a and extends substantially linearly in a direction parallel to a side of the metal substrate 30 as illustrated in Fig. 2A. As illustrated in Fig. 3, the first conductive member 50 is formed, for example, of a copper ribbon 50a covered with a coating material 50b made of an alloy of indium and copper. The first conductive member 50 is connected to the back electrode 38a by, for example, an ultrasonic solder.

A second conductive member 52 is connected substantially linearly to the end portion 34a without the insulation layer 36 and thus electrically connected to the metal substrate 30. The second conductive member 52 is connected to the back electrode 39 through the metal substrate 30 (the aluminum layer 34 and the stainless steel plate 32) acting as a conductor.

The second conductive member 52 is provided to collect the output from the positive electrode as will be described onto the outside. The second conductive member 52 is an elongate strip member as is the first conductive member 50; it is connected to the end portion 34a and extends substantially linearly in a direction parallel to a side of the metal substrate 30 as illustrated in Fig. 2A.
In the solar cell submodule 12, the first conductive member 50 and the second conductive member 52 are positioned adjacent to each other on one end portion and both extend substantially linearly and substantially parallel to each other.

The second conductive member 52 is composed similarly to the first conductive member 50 and formed, for example, of a copper ribbon 52a covered with a coating material 52b made of an alloy of indium and copper.
The first conductive member 50 and the second conductive layer 52 may be formed of a tin-coated copper ribbon. Further, the first conductive member 50 and the second conductive member 52 may be secured by such means as, for example, a conductive adhesive and conductive tape in lieu of by an ultrasonic solder.

The photoelectric conversion elements 46 of this embodiment may be fabricated by any of known methods used to fabricate CIGS solar cells. The separation grooves (P1) 41 of the back electrodes 38, the grooves (P2) 43 reaching the back electrodes 38, and the opening grooves (P3) 45 reaching the back electrodes 38 may be formed by laser scribing or mechanical scribing.

In the photoelectric conversion unit 48, light entering the photoelectric conversion elements 30 from the side bearing the transparent electrodes 44 passes through the transparent electrodes 44 and the buffer layers 42 and causes the photoelectric conversion layers 40 to generate electromotive force, thus producing a current that flows, for example, from the transparent electrodes 44 to the back electrodes 38. Note that the arrows shown in Fig. 3 indicate the direction of the current, and the direction in which electrons move is opposite to that of the current. In the photoelectric conversion unit 48, therefore, the leftmost back electrode 39 in Fig. 3 has the positive polarity (plus polarity) and the rightmost back electrode 38 has the negative polarity (minus polarity).

According to this embodiment, the back electrode 39 is connected to the aluminum layer 34 of the metal substrate 30, and the second conductive member 52 is connected to the aluminum layer 34 of the metal substrate 30. Thus, the back electrode 39 and the second conductive member 52 can be electrically connected through the aluminum layer 34 and the stainless steel plate 32 of the metal substrate 30 acting as conductor. The first conductive member 50 is connected to a back electrode 38a. Thus, the electricity generated by the solar cell submodule 12 can be collected from the solar cell submodule 12 through the first conductive member 50 and the second conductive member 52 positioned adjacent to each other.
The first conductive member 50 has a negative polarity; the second conductive member 52 has a positive polarity. The polarities of the first conductive member 50 and the second conductive layer 52 may be reversed; their polarities may vary according to the configuration of the photoelectric conversion elements 46, the configuration of the solar cell module 10, and the like.

According to this embodiment, the first conductive member 50 and the second conductive member 52 extend parallel to each other and are longer along a side of the metal substrate 30 as illustrated in Fig. 2A.
As illustrated in Fig. 2B, at least the back electrode 39 electrically connected to the second conductive member 52 preferably has a length X not less than a half of L, the length of a side of the metal substrate 30. Thus, a good conductivity can be ensured between the back electrode 39 and the metal substrate 30.

According to this embodiment, the second conductive member 52 is connected through the metal substrate 30 to the photoelectric conversion element 46 positioned at the positive end of the series-connected photoelectric conversion elements 46. Therefore, the second conductive member 52 is connected to the photoelectric conversion element 46 having a highest potential of all the photoelectric conversion elements 46 in the photoelectric conversion unit 48. Thus, the electricity collected from the second conductive member 52 has the highest of the potentials produced.

In this embodiment, the metal substrate 30, e.g., the aluminum layer 34 and the stainless steel plate 32, is used as a conductor. The metal substrate 30, although a clad substrate formed of the stainless steel plate 32 and the aluminum layers 34, 35, does not consume the current generated by the solar cell submodule 12 by virtue of sufficiently high conductivities of both the stainless steel plate 32 and the aluminum layers 34, 35.

Next, the connection box 22 will be described in detail.
As illustrated in Fig. 2A, the connection box 22 has a substantially rectangular external shape. The solar cell submodule 12 has a substantially rectangular notch in one of the four corners thereof at an end of a side thereof on which the first conductive member 50 and the second conductive member 52 are provided. The notch has the size of a region 24 corresponding to the external dimensions of the connection box 22.
The region 24 is also provided in the solar cell module body 10a incorporating the solar cell submodule 12. The connection box 22 is secured in the region 24 in a direction such that the thickness of the former agrees with that of the solar cell module body 10a. The connection box 22, as incorporated, does not project from the external surface of the metal substrate 30 as it was before the notch was cut out from the metal substrate 30.
As illustrated in Fig. 2B, a width W1 of the connection box 22 is the sum of, for example, a region extending from an edge 30c of the metal substrate 30 and free from the photoelectric conversion unit 48, the sum of the widths of the first conductive member 50 and the second conductive member 52, and the width of one photoelectric conversion element 46.

A thickness t of the connection box 22 illustrated in Fig. 2C is substantially equal to a thickness T of the solar cell module body 10a illustrated in Fig. 1. The thickness T of the solar cell module body 10a corresponds to the sum of the thicknesses of the solar cell submodule 12 forming a part of the solar cell module 10a, the bond/seal layer 14, the top surface protection layer 16, the bond/seal layer 18, and the back sheet 20 in the direction in which these layers are superposed.
Thus, the thickness t of the connection box 22 is substantially the same as the thickness T of the solar cell module body 10a, and the connection box 22 is incorporated in the solar cell module 10 without projecting from the original external shape of the metal substrate 30 of the solar cell submodule 12.

As illustrated in Fig. 1, the connection box 22 comprises a housing 60 and a base 61 formed inside the housing 60. The distance between a top surface 60b of the housing 60 and a bottom surface 60c thereof is equal to the thickness t of the connection box 22 and, as described above, substantially equal to the thickness T of the solar cell module body 10a.
With the connection box 22 attached in the direction such that its thickness agrees with that of the solar cell module body 10a, the top surface 60b of the housing 60 is flush with a top surface 16a of the top surface protection layer 16, and the bottom surface 60c of the housing 60 is flush with a surface 20a of the back sheet 20.

The housing 60 has the base 61 formed in an internal space 60a thereof. On a base surface 61a of the base 61, there are provided a lead wire 62, a crimp member 64, and a cable 66.
The lead wire 62 is connected to the first conductive member 50 by, for example, a conductive bond 70. The lead wire 62 is mechanically joined to a cable core 66a of the cable 66 by the crimp member 64. The cable 66 is secured to the base surface 61a by a fastener 69 provided in the base 61. The crimp member 64 is not specifically limited, provided that it is capable of mechanically joining the lead wire 62 and the cable core 66a of the cable 66. The crimp member 64 may be, for example, a crimp contact.

In the connection box 22, the height of the base surface 61a of the base 61 is adjusted so that the first conductive member 50 may be connected, kept straight as originally routed, to the lead wire 62 without the need to bend the first conductive member 50.
Although Fig. 1 only illustrates the connection of the first conductive member 50 and the cable 66, the second conductive member 52 is likewise connected to the lead wire 62 provided on the base surface 61a by the conductive bond 70, and the lead wire 62 is mechanically joined to the cable core of the cable 68 by the crimp member 64. The second conductive member 52 is likewise connected to the lead wire 62, kept straight as originally routed, without the need to bend the second conductive member 52.

According to this embodiment, the connection box 22 has a configuration such that, for example, the upper half portion of the housing 60 is removable. To connect the connection box 22 having such a configuration to the solar cell module body 10a, the upper half portion is first removed, and the first conductive member 50 and the second conductive member 52 are connected to the respective lead wires 62 by the conductive bond 70 and, hence, to the

cables

66, 68. Then, the internal space 60a of the housing 60 is filled with a seal bond 72 to mount the upper half portion. Thus, the internal space 60a of the connection box 22 is sealed to maintain the first conductive member 50 and the second conductive member 52 connected respectively to the

cables

66, 68, and, hence, connected to the solar cell module body 10a, completing the solar cell module 10.

The solar cell module 10 according to this embodiment has the connection box 22 provided in the region 24, which is a notch formed at a corner of the solar cell submodule 12, wherein the thickness t of the connection box 22 is substantially equal to the thickness T of the solar cell module body 10a. Thus, the solar cell module 10 has no projections from the surface thereof and has a uniform thickness, unlike conventional solar cell modules having the connection box projecting from the surface thereof. Therefore, the work efficiency in transportation and installation of the solar cell module 10 increases.
Thus, although transporting conventional solar cell modules stacked on each other required a spacer having a recess for accommodating the connection box, etc. and other like jigs, the solar cell module 10 according to this embodiment requires no such spacers or the like jigs. Thus, transportation costs can be reduced.

Further, since the solar cell module 10 according to this embodiment has no projections from the surface thereof, the solar cell module 10 permits easy handling and an increased installation work efficiency. Therefore, installation costs can be reduced and, since the connection box of the solar cell module of the invention does not have a chance of breaking upon impact, the reliability of the solar cell module can also be increased.
Thus, the transportation costs and installation costs can be reduced, as well as the costs of the solar cell module.

The first conductive member 50 and the second conductive member 52 can be connected, kept substantially straight, to the connection box 22, without causing stress to the first conductive member 50 and the second conductive member 52 as by bending. Therefore, problems such as breaks in cables caused by bending and the like can be minimized and reliability of the solar cell module 10 based on an increased durability and the like can be enhanced.
Further, since the first conductive member 50 and the second conductive member 52 can be connected, kept straight, to the lead wires 62 without the need of bending, the first conductive member 50 and the second conductive member 52 can be connected to the respective lead wires 62 more readily and, hence, with an increased work efficiency.

Further, although a portion of the metal substrate 30 is cut out according to this embodiment, the invention is not limited this way. For example, one may use a metal substrate having a part previously cut out for attachment of the connection box 22, provided that the connection box 22 can be incorporated without projecting from the external surface of the solar cell module 10.
According to this embodiment, where the connection box 22 is attached to a corner of the solar cell submodule 12 and, therefore, not located in the proximity of the center of the solar cell module as was conventionally the case, the connection box does not hinder the solar cell module from being bent inwardly or outwardly, provided that a flexible metal substrate is used.

Although the first conductive member 50 and the second conductive member 52 are positioned adjacent to each other at an end portion of the solar cell submodule 12 according to this embodiment, the invention is not limited to this configuration. For example, the first conductive member 50 may be provided at one end portion (back electrode 38a) of the metal substrate, and the second conductive member 52 at the other end portion (back electrode 39). With this configuration, when the connection box 22 is located in the position illustrated in Fig. 2A, the second conductive member 52 is disposed on the insulation layer 36 of the metal substrate 30 so as to extend along the photoelectric conversion unit 48 and connected to the connection box 22.

The configuration of the solar cell submodule 12 is not specifically limited to that of this embodiment. However, when the first conductive member 50 and the second conductive member 52 can be positioned at one end portion as in the solar cell submodule 12 according to this embodiment, their connection to the connection box 22 is made easier and there is no need to route around the line from the second conductive member 52 as described above, so that the length of wiring can be reduced.

Next, a second embodiment of the invention will be described.
Fig. 4A is a top plan view of a solar cell submodule of the solar cell module according to the second embodiment of the invention; Fig. 4B is an enlarged top plan view schematically illustrating how the connection box is disposed in the solar cell module according to the second embodiment of the invention; and Fig. 2C is a schematic view illustrating the thicknesses of the solar cell module according to the second embodiment of the invention and the connection box.
The same components of this embodiment as those of the solar cell module 10 according to the first embodiment illustrated in Figs. 1 to 3 are given like reference characters, and a detailed description thereof will be omitted.

As illustrated in Figs. 4A and 4B, a solar cell submodule 12a according to this embodiment has a connection box 22a that is different in dimensions from that of the solar submodule 12 (see Figs. 2A and 2B) according to the first embodiment; the other components and configuration are similar to those of the solar submodule 12 (see Figs. 2A and 2B) according to the first embodiment, and their description will be omitted.

The connection box 22a of this embodiment has the same thickness t as the connection box 22 of the first embodiment but has a width W2 that is smaller than the width W1 of the connection box 22. The width W2 of the connection box 22 of this embodiment is slightly greater than the sum of the widths of the first conductive member 50 and the second conductive member 52 and approximately equal to the sum of widths of two photoelectric conversion elements 46. Thus, the connection box 22a can be reduced in dimensions. The connection box 22a has the same internal configuration as the connection box 22 and therefore a detailed description thereof will be omitted.
Different from the first embodiment only in that the width W2 of the connection box 22a is smaller, this embodiment produces the same effects as the first embodiment, although a detailed description thereof will be omitted.

In any of the above embodiments, the metal substrate 30 used in this embodiment is a clad substrate, as described above, formed of the stainless steel plate 32 as a core material and the aluminum layers 34, 35 as coating layers. The composition of the stainless steel plate 32 may be determined as appropriate from the results of a stress calculation based on material properties of the insulation layer and the photoelectric conversion elements used. The stainless steel plate 32 may be formed, for example, of austenitic stainless steel (thermal expansion coefficient: 17 x 10^-61/deg C), carbon steel or ferritic stainless steel (10 x 10^-61/deg C) to control the thermal expansion coefficient of the photoelectric conversion elements as a whole.
The metal substrate 30 may use a plate member formed, for example, of steel such as mild steel, 42 invar alloy, kovar alloy (5 x 10^-61/deg C) or 36 invar alloy (< 1 x 10^-61/deg C) in lieu of the stainless steel plate 32.

The stainless steel plate 32 may have any thickness as appropriate according to the ease of handling in the manufacture of photoelectric conversion elements and in use (strength and flexibility); the thickness is preferably in a range of 10 micrometers to 1 mm.

The rigidity required of the stainless steel plate 32, of which the elastic limit stress without plastic deformation is of critical importance, is defined in terms of yield stress or 0.2% proof-stress. The 0.2% proof-stress and the temperature dependency of the stainless steel plate 32 is described in "Steel Material Handbook" edited by the Japan Institute of Metals and the Iron and the Steel Institute of Japan, published by Maruzen Company, Limited or in "Stainless Steel Handbook (3rd edition)," edited by the Japan Stainless Steel Association and published by Nikkan Kogyo Shimbun. The 0.2% proof-stress of the stainless steel plate 32, although dependent upon the degree of machining and thermal refining, is preferably 250 MPa to 900 MPa at room temperature. Although the photoelectric conversion elements (photoelectric conversion unit) of the solar cell module reaches a high temperature of 500 deg C or higher at the time of manufacture, generally about 70 % of the proof stress of the steel is maintained at 500 deg C. Although dependent upon the degree of machining and thermal refining, the proof stress of aluminum at room temperature is 300 MPa or more but decreases to 1/10 or lower at a temperature of 350 deg C or higher. Accordingly, the elastic limit stress and the thermal expansion of the metal substrate 30 at a high temperature mostly depend upon the high temperature characteristics of the stainless steel plate 32. The Young's moduli of aluminum and stainless steel and their temperature dependencies needed for stress calculation are described in "Elastic Moduli of Metallic Materials" by The Japan Society of Mechanical Engineers.

The aluminum layers 34, 35 may be formed using, for example, an alloy of a Class 1000 pure aluminum as defined by Japan Industrial Standard (JIS), an Al-Mn alloy, an Al-Mg alloy, an Al-Mn-Mg alloy, an Al-Zr alloy, an Al-Si alloy, or an Al-Mg-Si alloy and another metallic element (see "Aluminum Handbook, 4th edition)" (published in 1990 by Japan Light Metal Association). The aluminum layers 34, 35 may contain a trace amount of a metallic element such as Fe, Si, Mn, Cu, Mg, Cr, Zn, Bi, Ni, and Ti.

The thicknesses of the aluminum layers 34, 35 may be determined as appropriate according to the results of stress calculations based upon the whole layer configuration and the material properties of the solar cell module. When integrated with the metal substrate 30, the aluminum layers 34, 35 have a thickness in a range of 0.1 micrometers to 500 micrometers. Interposition of the aluminum layers 34, 35 between the stainless steel plate 32 and the insulation layers 36, 37 formed of the anodized film moderates a stress that may act upon the insulation layers 36, 37 upon thermal expansion due to temperature variation. When forming the insulation layers 36, 37 on the metal substrate 30, the thicknesses of the aluminum layers 34, 35 decrease as they undergo anodization, washing prior to anodization, and polishing. Therefore, the thicknesses of the aluminum layers 16, 17 need to allow for such reduction in thickness.

The aluminum layers 34, 35 may be formed by any method as appropriate, provided that adhesion between the stainless steel plate 32 and the aluminum layers 34, 35 are ensured. The aluminum layers 34, 35 may be formed on the stainless steel plate 32 by, for example, vapor-phase film deposition methods such as vapor deposition, sputtering, etc., hot-dip plating technique by immersion in a molten aluminum bath, a connecting method such as pressure connection by rolling after surface cleaning, and any other method as appropriate.
When using hot-dip plating, caution should be used not to admit fragile intermetallic compounds at the interface between the stainless steel plate 32 and the aluminum layers 34, 35. From a viewpoint of manufacturing costs and productivity, the aluminum layers 34, 35 are preferably formed by pressure connection technique by rolling or other means.

The insulation layers 36, 37 typically are anodized films having fine pores produced by anodization of the aluminum layers 34, 35. These anodized films have an enhanced insulation performance.

Anodization is achieved by immersing the metal substrate 30 as the positive electrode in an electrolytic solution together with the negative electrode and applying a voltage between the positive and negative electrodes. Where necessary, the anodization may include steps of subjecting the aluminum layers 34, 35 to washing and polishing/smoothing processes. The negative electrode is typically formed of carbon, aluminum, or the like. The electrolyte is not specifically limited; preferably used is one or more kinds of acids selected from sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, and amidosulfonic acid to prepare an acidic electrolytic solution. The anodizing conditions vary with the kinds of electrolytes used and are not specifically limited. By way of example, appropriate conditions are an electrolyte concentration of 1 % to 80 %, a liquid temperature of 5 deg C to 70 deg C, a current density of 0.005 A/cm² to 0.60 A/cm², a voltage of 1 V to 200 V, and an electrolysis time of 3 min to 500 min. The electrolytic solution preferably contains a sulfuric acid, phosphoric acid, or oxalic acid or mixture thereof. Electrolytes as described above are used preferably with an electrolyte concentration of 4 mass% to 30 mass%, a current density of 0.05 A/cm² to 0.30 A/cm², and a voltage of 30 V to 150 V.

In anodization of the aluminum layers 34, 35, oxidation reaction takes place from the surfaces and substantially vertically to produce anodized films. Where any of the above electrolytic solution is used, the anodized films obtained will have a number of fine columns tightly arranged having a substantially hexagonal form as seen in planar view. The fine columns each have a pore at the core, the bottom being somewhat rounded. At the bottom of the fine columns is formed a barrier layer with a thickness of 0.02 micrometers to 0.1 micrometers is formed. In lieu of the acidic electrolytic solution, a neutral electrolytic solution such as one containing boric acid, etc. may be used for electrolytic treatment, whereby anodized films having a denser composition can be obtained in place of those where the porous fine columns are arranged. After producing the porous anodized films using an acidic electrolytic solution, pore filling technique may be used to perform additional electrolytic treatment in order to increase the thickness of the barrier layer.

The thicknesses of the insulation layers 36, 37 are not specifically limited, provided that the insulation layer 14 has insulation properties and a surface hardness sufficient to prevent damage that may be caused by a mechanical impact during handling. An excessive thickness thereof, however, may present problems from a viewpoint of flexibility. Accordingly, a preferred thickness of the insulation layers 36, 37 is 0.5 micrometers to 50 micrometers; the thickness can be controlled using the electrolysis time in constant current electrolysis as well as constant voltage electrolysis.
Where the insulation layers 36, 37 are formed by anodization technique, the lateral sides of the metal substrate 30 (stainless steel plate 32) need to be masked for insulation to prevent formation of a local battery between the stainless steel plate 32 and the aluminum layers 34, 35. Where an anodized film is formed on one of the aluminum layers 34, 35, the surface of the other of the aluminum layers 34, 35 needs to be masked for insulation in addition to the lateral sides of the metal substrate 30 (stainless steel plate 32).

The insulation layers 36, 37 are not limited to aluminum oxide layers produced by anodization. The insulation layers 36, 37 are exemplified by aluminum oxide films, silicon oxide films, and resin layers. The insulation layers 36, 37 may be formed, for example, by a CVD method, a PVD method, or a sol-gel method; the thicknesses are in a range of 1 micrometer to 100 micrometers, preferably 10 micrometers to 50 micrometers.

The back electrodes 38 and the transparent electrodes 44 of the photoelectric conversion elements 46 are provided both to collect current generated by the photoelectric conversion layers 40. Both the back electrodes 38 and the transparent electrodes 44 are each made of a conductive material. The transparent electrodes 44, provided on the side from which light is admitted, need to be pervious to light.

The back electrodes 38 are formed, for example, of Mo, Cr or W, or a material composed of two or more of these. The back electrodes 38 may have a single-layer structure or a laminated structure such as a dual-layer structure.
The back electrodes 38 have a thickness of 100 nm or more, preferably 0.45 micrometers to 1.0 micrometers.
The back electrodes 38 may be formed by any of vapor-phase film deposition methods as appropriate such as electron-beam deposition and sputtering.

The transparent electrodes 44 are formed, for example, of ZnO added with Al, B, Ga, Sb, etc., ITO (indium tin oxide), SnO₂, or a material composed of two or more of these. The transparent electrodes 44 may have a single-layer structure or a laminated structure such as a dual-layer structure. The thickness of the transparent electrodes 44, which is not specifically limited, is preferably 0.3 micrometer to 1 micrometer.
The transparent electrodes 44 may be formed by any of vapor-phase film deposition methods as appropriate such as electron-beam deposition and sputtering.

The buffer layers 42 are provided to protect the photoelectric conversion layers 40 when forming the transparent electrodes 44 and admit the light entering the transparent electrodes 44 into the photoelectric conversion layers 40.
The buffer layers 42 are formed, for example, of CdS, ZnS, ZnO, ZnMgO, or ZnS (O, OH) or a material composed of two or more of these.
The buffer layers 42 preferably have a thickness of 0.03 micrometers to 0.1 micrometers. The buffer layers 42 are formed, for example, by the chemical bath deposition (CBD) method.

The photoelectric conversion layers 40 absorb the incoming light admitted through the transparent electrodes 44 and the buffer layers 42 to generate current. According to this embodiment, the photoelectric conversion layers 40 are not specifically limited in configuration; they may be formed, for example, of a compound semiconductor having at least one kind of chalcopyrite structure. The photoelectric conversion layers 40 may be formed of at least one kind of compound semiconductor composed of a Ib group element, a IIIb group element, and a VIb group element.

For a high optical absorptance and a high photoelectric conversion efficiency, the photoelectric conversion layers 40 are preferably formed of at least one kind of compound semiconductor composed of at least one kind of Ib group element selected from the group consisting of Cu and Ag, at least one kind of IIIb group element selected from the group consisting of Al, Ga, and In, and at least one kind of VIb group element selected from the group consisting of S, Se, and Te. The compound semiconductor is exemplified by CuAlS₂, CuGaS₂, CuInS₂, CuAlSe₂, CuGaSe₂, CuInSe₂(CIS), AgAlS₂, AgGaS₂, AgInS₂, AgAlSe₂, AgGaSe₂, AgInSe₂, AgAlTe₂, AgGaTe₂, AgInTe₂, Cu(In1-xGax)Se₂(CIGS), Cu(In1-xAlx)Se₂, Cu(In1-xGax)(S, Se)₂, Ag(In1-xGax)Se₂, and Ag(In1-xGax)(S, Se)₂.

The photoelectric conversion layers 40 preferably contain CuInSe₂(CIS) and/or Cu(In,Ga)Se₂(CIGS), which is obtained by dissolving Ga in the former. CIS and CIGS are semiconductors each having a chalcopyrite crystal structure and reportedly have a high optical absorptance and a high photoelectric conversion efficiency. Further, CIS and CIGS have an excellent durability such that they are less liable to decrease in efficiency through exposure to light or other causes.

The photoelectric conversion layers 40 contain impurities for obtaining a desired semiconductor conductivity type. Impurities may be added to the photoelectric conversion layers 40 by diffusion from adjacent layers and/or direct doping into the photoelectric conversion layers 26. The photoelectric conversion layers 40 permit presence therein of a component element of I-III-VI group semiconductor and/or a density distribution of impurities; the photoelectric conversion layers 26 may contain a plurality of layer regions formed of materials having different semiconductor properties such as n-type, p-type, and i-type.
For example, a CIGS semiconductor, when given a thickness-wise distribution of Ga amount in the photoelectric conversion layers 40, permits control of band gap width, carrier mobility, etc. and thus achieves a high photoelectric conversion efficiency.

The photoelectric conversion layers 40 may contain single or two or more kinds of semiconductors other than I-III-VI group semiconductors. Such semiconductors other than I-III-VI group semiconductors include a semiconductor formed of a IVb group element such as Si (IV group semiconductor), a semiconductor formed of a IIIb group element and a Vb group element (III-V group semiconductor) such as GaAs, and a semiconductor formed of a IIb group element and a VIb group element (II-VI group semiconductor) such as CdTe.
The photoelectric conversion layers 40 may contain any other component than a semiconductor and impurities used to obtain a desired conductivity type, provided that no detrimental effects are thereby produced on the properties.
The photoelectric conversion layers 40 may contain a I-III-VI group semiconductor in any amount as deemed appropriate. The ratio of a I-III-VI group semiconductor contained in the photoelectric conversion layers 40 is preferably 75 mass% or more and, more preferably, 95 mass% or more and, most preferably, 99 mass% or more.

When the photoelectric conversion layers 40 of this embodiment are CIGS layers, the CIGS layers may be formed by such known film deposition methods as 1) multi-source co-evacuation methods, 2) selenization method, 3) sputtering method, 4) hybrid sputtering method, and 5) mechanochemical processing method.

1) Known multi-source co-evacuation methods include:
three-stage method (J.R. Tuttle et al, Mat. Res. Soc. Symp. Proc., Vol. 426 (1966), p. 143, etc.) and a simultaneous evaporation method by EC group (L. Stolt et al.: Proc. 13th ECPVSEC (1995, Nice) 1451, etc.).
According to the first-mentioned three-phase method, firstly, In, Ga, and Se are simultaneously evaporated under high vacuum at a substrate temperature of 300 deg C, which is then increased to 500 deg C to 560 deg C to simultaneously vapor-deposit Cu and Se, whereupon In, Ga, and Se are simultaneously evaporated. According to the latter method or the simultaneous evaporation method by EC group, Cu excess CIGS is vapor-deposited in an earlier stage of vapor deposition, and In excess CIGS is vapor-deposited in a later stage.

Following methods are among those where improvements have been made on the above methods to improve crystallinity of CIGS films.
a) Method using ionized Ga (H. Miyazaki et al, phys. stat. sol. (a), Vol. 203 (2006), p. 2603, etc.)
b) Method using radicalized Se (a pre-printed collection of speeches given at the 68th Academic Lecture by Japan Society of Applied Physics) (autumn of 2007, Hokkaido Kogyo Univ.), 7P-L-6, etc.)
c) Method using radicalized Se (a pre-printed collection of speeches given at the 54th Academic Lecture by Japan Society of Applied Physics) (spring of 2007, Aoyama Gakuin Univ.), 29P-ZW-14, etc.), and
d) Method using light excitation process (a pre-printed collection of speeches given at the 54th Academic Lecture by Japan Society of Applied Physics) (spring of 2007, Aoyama Gakuin Univ.), 29P-ZW-14, etc.).

2) The selenization method is also called two-stage method, whereby firstly a metal precursor formed of a laminated film such as a Cu layer/In layer, a (Cu-Ga) layer/In layer, or the like is formed by sputter deposition, vapor deposition, or electrodeposition, and the film thus formed is heated in selenium vapor or hydrogen selenide to a temperature of 450 deg C to 550 deg C to produce a selenide such as Cu(In_1-xGax)Se₂ by thermal diffusion reaction. This method is called vapor-phase selenization method. Another method available for the purpose is the solid-phase selenization method whereby solid-phase selenium is disposed on a metal precursor film to achieve selenization by solid-phase diffusion reaction using the solid-phase selenium as selenium source.

The selenization method may be implemented in several ways: selenium is previously mixed in a given ratio into the metal precursor film to avoid abrupt volume expansion that might take place in selenization process (T. Nakada et al, Solar Energy Materials and Solar Cells 35 (1994) 204-214, etc.); or selenium is sandwiched between thin metal films (e.g., as in Cu layer/In layer/Se layer ...... Cu layer/In layer/Se layer) to form a multiple-layer precursor film (T. Nakada et al, Proc. of 10th European Photovoltaic Solar Energy Conference (1991) 887 - 890, etc.).

Among the methods of forming a graded band gap CIGS film is one whereby firstly a Cu-Ga alloy film is disposed, and an In film is disposed thereon, subsequently achieving selenization by inclining the Ga density in the film thickness direction using natural thermal diffusion (K. Kushiya et al, Tech Digest 9th Photovoltaic Scienece and Engineering Conf. Miyazaki, 1996 (Intn. PVSEC-9, Tokyo, 1996) p. 149, etc.)

3) Known sputter deposition techniques include:
one using CuInSe₂ polycrystal as a target, one called two-source sputter deposition using Cu₂Se and In₂Se₃ as targets and using H₂Se/Ar mixed gas as sputter gas (J. H. Ermer, et al, Proc. 18th IEEE Photovoltaic Specialists Conf. (1985) 1655 - 1658, etc.) and
one called three-source sputter deposition whereby a Cu target, an In target, and an Se or CuSe target are sputtered in Ar gas (T. Nakada, et al, Jpn. J. Appl. Phys. 32 (1993) L1169 - L1172, etc.).

4) Known hybrid sputter deposition methods include one whereby metals Cu and In are subjected to direct current sputtering, while only Se is vapor-deposited (T. Nakada, et al., Jpn. Appl. Phys. 34 (1995) 4715 - 4721, etc.).

5) The mechanochemical processing method is a method whereby a material selected according to the CIGS composition is placed in a planetary ball mill container and mixed by mechanical energy to obtain pulverized CIGS, which is then applied to a substrate by screen printing and annealed to obtain a CIGS film (T. Wada et al, Phys. stat. sol. (a), Vol. 203 (2006) p. 2593, etc.).

Other methods of forming a CIGS film include screen printing method, close-spaced sublimation method, MOCVD method, and spray method. For example, the screen printing method or the spray method may be used to form a fine-particle film containing a Ib group element, a IIIb group element, and a VI group element on a substrate and obtain a crystal having a desired composition by, for example, pyrolysis treatment (which may be a pyrolysis treatment carried out under a VIb group element atmosphere) (JP 9-74065 A, JP 9-74213 A, etc.).

The configuration of the metal substrate of the solar cell submodule 12 is not limited to the clad substrate having the stainless steel plate 32 with the aluminum layers 34, 35 formed on both sides thereof. The metal substrate may have the aluminum layer 34 only on the top surface 32a of the stainless steel plate 32 and the insulation layer 36 formed on the aluminum layer 34.
The metal substrate may have an aluminum layer formed over the whole surface of the stainless steel plate 32. In this case, the aluminum layer may have the same composition as the aluminum layer 34 of this embodiment.
The metal substrate may be formed only of an aluminum substrate provided on at least one of its top and bottom surfaces with an insulation layer formed of an anodized film using aluminum.

The metal substrate is rectangular and the end portions of at least two sides thereof each preferably have a region without the insulation layer, so that the metal substrate is exposed. In this case, the two sides preferably are two opposite sides.
Further, the metal substrate is rectangular and the end portions of at least two sides thereof each may have a conductor connected to a conductive portion of the metal substrate. Also in this case, the two sides preferably are two opposite sides.

In any of the above embodiments, the solar cell submodule may be a thin-film type thin-film solar cell submodule, an integrated type solar cell submodule, or a grid type solar cell submodule.
In any of the above embodiments, the photoelectric conversion unit of the solar cell submodule is not specifically limited to one comprising CIGS based thin-film solar cells (CIGS based thin-film solar cells). The photoelectric conversion unit may comprise for example a CIS based thin-film solar cells or CIS based thin-film photoelectric conversion elements, thin-film silicon based thin-film solar cells or thin-film silicon-based thin-film photoelectric conversion elements, CdTe based thin-film solar cells or CdTe based thin-film photoelectric conversion elements, dye-sensitized thin-film solar cells or dye-sensitized thin-film photoelectric conversion elements, or organic thin-film solar cells or organic thin-film photoelectric conversion elements.

The present invention is basically as described above. While the solar cell module of the invention has been described above in detail, the present invention is by no means limited to the above embodiments, and various improvements or design modifications may be made without departing from the scope and spirit of the present invention.

10 solar cell module
10a solar cell module body
12 solar cell submodule
14, 18 bond/seal layers
16 top surface protection layer
20 back sheet
30 a metal substrate
32 stainless steel plate
34, 35 aluminum layers
36, 37 insulation layers
38 back electrodes
40 photoelectric conversion layers
42 buffer layers
44 transparent electrodes
46 photoelectric conversion elements
48 photoelectric conversion unit
50 first conductive member
52 second conductive member
60 housing
62 lead wires
64 crimp member
66, 68 cables

Claims

A solar cell module comprising
a solar cell module body including a submodule provided with a photoelectric conversion unit having a function capable of obtaining electricity from light, and a positive electrode and a negative electrode,
a first conductive member connected to the negative electrode of said photoelectric conversion unit,
a second conductive member connected to the positive electrode of said photoelectric conversion unit,
a connection box connected to said first conductive member and said second conductive member,
wherein said connection box is provided inside said solar cell module body and has a thickness substantially equal to that of said solar cell module body.
The solar cell module according to Claim 1, wherein said connection box is provided in a region that is formed by cutting out a part of said solar cell module body.
The solar cell module according to Claim 1 or 2, wherein said first conductive member and said second conductive member are connected to said connection box without being bent.
The solar cell module according to any one of Claims 1 to 3, wherein said first conductive member and said second conductive member are arranged substantially linearly at one end portion of said submodule and connected to said connection box in a manner kept substantially linear.
The solar cell module according to any one of Claims 1 to 4,
wherein said submodule comprises further a substrate used as a conductor and provided with said photoelectric conversion unit, said positive electrode is positioned at one end portion of said photoelectric conversion unit and said negative electrode is positioned at another end portion of said photoelectric conversion unit, and
wherein said substrate is connected to one of said positive electrode and said negative electrode, and said first conductive member or said second conductive member is provided on said substrate at an end of said substrate that is not connected to said one of said negative electrode and said positive electrode.
The solar cell module according to Claim 5,
wherein said substrate has a conductive portion and an insulation layer formed on at least one side of said conductive portion, and said photoelectric conversion unit is formed on said insulation layer, and
wherein said conductive portion of said substrate is used as said conductor and connected to said one of said positive electrode and said negative electrode, and said first conductive member or said second conductive member is provided on said conductive portion of said substrate at an end of said conductive portion that is not connected to said one of said negative electrode and said positive electrode.
The solar cell module according to Claim 6, wherein said insulation layer is formed of anodized aluminum.
The solar cell module according to any one of Claims 1 to 7, wherein said submodule is a thin-film solar cell submodule.
The solar cell module according to any one of Claims 1 to 8, wherein said submodule is an integrated type thin-film solar cell submodule.
The solar cell module according to any one of Claims 1 to 8, wherein said submodule is a grid type solar cell submodule.
The solar cell module according to any one of Claims 1 to 10, wherein said photoelectric conversion unit comprises one kind of thin-film solar cells selected from the group consisting of CIS based thin-film solar cells, CIGS based thin-film solar cells, thin-film silicon-based thin-film solar cells, CdTe based thin-film solar cells, III-V group based thin-film solar cells, dye-sensitized thin-film solar cells, and organic thin-film solar cells.