Solar battery module and solar battery array

A solar battery module (40) includes a stack of: a plurality of solar battery strings (30) and bus sections (32) connected to both ends of each of the plurality of solar battery strings (30); flexible resin layers (33a through 33c); and a flexible resin film (34). The flexible resin layers (33a through 33c) and the flexible resin film (34) have, on a light receiving surface side of solar battery cells (20), holes through which the bus sections (32) are each partially exposed. The exposed parts of the bus sections (32) serve as a respective plurality of electrically-connecting means (32a). A solar battery array (41) includes a plurality of solar battery modules (40). The plurality of solar battery modules (40) are electrically connected with each other via the plurality of electrically-connecting means (32a). This makes it possible to achieve a large-scale solar battery array (41) with high mechanical strength.

TECHNICAL FIELD

The present invention relates to a solar battery module and a method for producing a solar battery module.

BACKGROUND ART

In recent years, a solar battery module has been attracting attention in view of effective use of resources and prevention of environmental contamination etc., because the solar battery module directly converts sunlight into electrical energy. In particular, since there has been increasing need for a lightweight and large-area solar battery module, development of such a solar battery module has been carried out.

For example, Patent Literature 1 discloses a solar battery module mounted on a sheet member. The solar battery module shown in Patent Literature 1 is described below with reference toFIGS. 12 and 13.FIG. 12is a plan view illustrating (i) a sheet member61and a solar battery module60mounted on the sheet member61.FIG. 13is a cross-sectional view illustrating the solar battery module60.

As illustrated inFIG. 12, the solar battery module60is sewed on the sheet member61with a thread62. Further, as illustrated inFIG. 13, the solar battery module60is configured such that solar battery cells65are sealed within a sealing resin66, which is sandwiched between a light receiving surface protection film63and a back surface protection film64.

According to Patent Literature 1, a large-area solar battery module is formed by sewing a plurality of the foregoing solar battery modules60onto the sheet member61. Note however that, while volume of the light receiving surface protection films63and the back surface protection films64with respect to volume of the large-area solar battery module is approximately 66%, volume of the sheet member61with respect to the volume of the large-area solar battery module is approximately 33%. Further, the sheet member61is greater in weight than the light receiving surface protection films63etc., because the sheet member is made from material with high mechanical strength. Accordingly, total weight of the large-area solar battery module is markedly large because of the sheet member61.

On the other hand, there has been developed a large-area solar battery sheet that is constituted by a combination of flexible solar battery modules without a sheet member. For example, a conventional solar battery sheet array illustrated inFIG. 15is described below. (a) ofFIG. 15is a plan view illustrating the solar battery sheet array. (b) ofFIG. 15is a cross-sectional view taken along line I-I′ of (a) ofFIG. 15.

The solar battery sheet array illustrated inFIG. 15is constituted by a plurality of unit solar battery sheets110.FIG. 14illustrates one of the plurality of unit solar battery sheets110. (a) ofFIG. 14is a plan view illustrating one of the unit solar battery sheet. (b) ofFIG. 14is a cross-sectional view taken along line H-H′ of (a) ofFIG. 14. The unit solar battery sheet110is configured such that (i) solar battery cells104are electrically connected in series with one another via inter connectors105, and (ii) both ends of an electrical connection among the solar battery cells104are connected to respective bus sections106a, which collect electric power.

Each of the bus sections106aof the unit solar battery sheet110is protruded from a flexible resin film101, a back surface protection member102, and a silicon resin103so that the plurality of unit solar battery sheets110can be electrically connected with one another as illustrated inFIG. 15.

The solar battery sheet array shown inFIG. 15is configured such that protruded parts of bus sections106of adjacent ones of the plurality of unit solar battery sheets110are welded together to form a welded part107and thereby the plurality of unit solar battery sheets110are electrically connected with one another via the welded parts107. In addition, adjacent ones of the plurality of unit solar battery sheets110are physically connected with each other with use of an adhesive agent108. The adhesive agent108fixes also a corresponding one of the welded parts107, and has protection films109on its both surfaces.

According to the configuration as shown inFIG. 15, a large-area solar battery sheet array is formed without a sheet member. Therefore, with this configuration, it is possible to achieve a lightweight and large-area solar battery sheet array.

CITATION LIST

Patent Literatures

Patent Literature 1

SUMMARY OF INVENTION

Technical Problem

However, according to the solar battery sheet array shown inFIG. 15, a connection part between adjacent ones of the plurality of solar battery modules110is not uniform in its flexibility and strength. For example, see a cross-sectional view taken along line J-J′. According to the cross-sectional view, a left one-third of the connection part between adjacent ones of the plurality of solar battery modules110is constituted by the protection films109, the adhesive agent108, and corresponding ones of the bus sections106. On the other hand, the other two-thirds of the connection part is constituted by the protection films109and the adhesive agent108. That is, the connection part shown in the cross-sectional view taken along line J-J′ is not uniform in its structure.

For example, in a case where the protection films109are made from a radiation-resistant film having high flexibility and low strength, the two-thirds of the connection part shown in the cross-sectional view taken along line J-J′ is constituted by (i) the protection films109with low strength and (ii) the adhesive agent108. That is, the two-thirds of the connection part has markedly low strength.

On the other hand, for example in a case where the protection films109are made from a radiation-resistant film having low flexibility and high strength, the left one-third of the connection part shown in the cross-sectional view taken along line J-J′ includes (i) the protection films109with low flexibility and (ii) the bus sections106made from metal. That is, the left one-third of the connection part has markedly low flexibility.

As such, according to the solar battery sheet array shown inFIG. 15, it is difficult to achieve both of flexibility and mechanical strength of the connection part between adjacent ones of the plurality of solar battery modules.

The present invention has been made in view of the problems, and an object of the present invention is to provide (i) a large-scale solar battery array with improved flexibility and improved mechanical strength and (ii) a solar battery module for constituting the solar battery array.

Solution to Problem

In order to attain the above object, a solar battery module in accordance with the present invention is a solar battery module for constituting a solar battery array, including: at least one solar battery string that is constituted by a plurality of solar battery cells electrically connected in series with each other; bus sections electrically connected with respective endmost ones of the plurality of solar battery cells that constitute said at least one solar battery string; and at least one flexible resin layer provided on each of both sides, which are a first side and a second side, of the solar battery module so as to sandwich said at least one solar battery string and the bus sections, the first side of the both sides of the solar battery module having first holes, through which the bus sections are each partially exposed, and the bus sections having areas which are exposed through the respective first holes, the areas serving as a respective plurality of electrically-connecting means.

A plurality of solar battery modules in accordance with the present invention are to constitute a solar battery array by being electrically connected with each other. In a case where each of the plurality of the solar battery modules is constituted by a flexible material, the each of the plurality of the solar battery modules is used as a flexible solar battery sheet. Accordingly, the solar battery array constituted by the plurality of solar battery modules is used as a flexible solar battery sheet array.

The plurality of solar battery modules in accordance with the present invention are electrically connected with each other via the plurality of electrically-connecting means of the bus sections. Note here that the plurality of electrically-connecting means of the bus sections can be connected with a wire by soldering etc. According to this configuration, the plurality of solar battery modules can be connected with each other via the wire. The bus sections are connected with respective endmost ones of the plurality of solar battery cells connected with each other, and collect electric power. Generally, the bus sections are made from metal.

According to this configuration, the plurality of electrically-connecting means of the bus sections are exposed through the respective first holes. Therefore, each of the bus sections is configured such that it does not protrude from the at least one flexible resin layer. Accordingly, there are no other members (e.g., the bus sections) between adjacent ones of the plurality of solar battery modules when the plurality of solar battery modules are electrically connected with each other. This makes it possible to achieve an advantage that the connected plurality of solar battery modules as a whole maintains its flexibility and keeps its mechanical strength uniform.

A solar battery array in accordance with the present invention includes: a plurality of the foregoing solar battery modules, the plurality of solar battery modules being electrically connected in series with each other via corresponding ones of the plurality of electrically-connecting means, each of which serves as an end of an electrical connection in a corresponding one of the solar battery strings electrically connected in series with each other.

According to this configuration, it is possible to easily produce a large-scale solar battery array in accordance with the present invention by connecting the plurality of solar battery modules. In addition, according to the solar battery array in accordance with the present invention, it is possible to improve flexibility of the entire solar battery array because there are no members such as the bus sections between adjacent ones of the plurality of solar battery modules.

Advantageous Effects of Invention

A solar battery module in accordance with the present invention includes a plurality of electrically-connecting means on one of both sides of the solar battery module. Accordingly, by combining a plurality of such solar battery modules, it is possible to make a large-scale solar battery array having improved flexibility and improved mechanical strength.

DESCRIPTION OF EMBODIMENTS

A first embodiment in accordance with the present invention is described below with reference toFIGS. 1 through 8.

First, the following description discusses, with reference toFIGS. 2 and 3, how solar battery cells20used in the present embodiment are schematically configured.FIG. 2is a plan view illustrating a light receiving surface of one of the solar battery cells20.FIG. 3is a cross-sectional view, illustrating the solar battery cell20, which is taken along line A-A′ ofFIG. 2.

Each of the solar battery cells20has (i) a light receiving surface for receiving sunlight and (ii) a non-light receiving surface opposed to the light receiving surface. Note that, in this Specification, a side on which the light receiving surface of each of the solar battery cells20is situated is hereinafter referred to as a light receiving surface side, whereas the other side on which the non-light receiving surface of the each of the solar battery cells20is situated is hereinafter referred to as a non-light receiving surface side.

As illustrated inFIGS. 2 and 3, each of the solar battery cells20is constituted by a multilayered semiconductor layer22, an n-type electrode25, p-type electrodes26, and a back surface electrode27. The multilayered semiconductor layer22is constituted by: a solar battery layer23including a p-n junction between a p-type region and an n-type region; a contact layer24via which the p-type electrodes26and the solar battery layer23are electrically connected with each other; and a contact layer29via which the n-type electrode25and the solar battery layer23are electrically connected with each other.

The n-type electrode25has a comb-teeth shape, and is provided on a surface, of the contact layer29, which is on the light receiving surface side. Each of the p-type electrodes26has a rectangular shape, and is provided on a surface, of the contact layer24, which is on the light receiving surface side. The back surface electrode27covers an entire surface of each of the solar battery cells20, and is provided on a surface, of the contact layer24, which is on the non-light receiving surface side.

In the present embodiment, each of the solar battery cells20is provided with (i) the n-type electrode25having three pads and (ii) three p-type electrodes26. Note, however, that the present invention is not limited to this configuration. Further, shape of each of the back surface electrode27, the n-type electrode25, and the p-type electrodes26is not limited to those described above, as long as they function as constituents of each of the solar battery cells20. Furthermore, the configurations of the n-type electrode25and the p-type electrodes26are interchangeable.

Each of the solar battery cells20has, on its light receiving surface side, inter connectors31provided on the n-type electrode25and on the p-type electrodes26. The each of the solar battery cells20can further have an antireflective film on its light receiving surface.

(Production Method for Solar Battery Cells20)

The following description discusses a production method for the solar battery cells20with reference toFIGS. 2 and 3.

The production method for the solar battery cells20includes: a step of forming epitaxial layers on a semiconductor substrate; a step of forming a back surface electrode27on the non-light receiving surface side; a step of removing the semiconductor substrate; a step of forming n-type electrodes25and p-type electrodes26on the light receiving surface side; and a step of separating out the solar battery cells20.

Each of the steps included in the production method for the solar battery cells20is specifically described below. Note, however, that a production method of the present invention is not limited to the production method as described below.

(1) Step of Forming Epitaxial Layers on Semiconductor Substrate

The semiconductor substrate used in this step is for example: an elemental semiconductor substrate such as that made from silicon (Si) and/or germanium (Ge); or a compound semiconductor substrate such as that made from gallium arsenic (GaAs). The semiconductor substrate is preferably a single crystal semiconductor substrate.

First, layers are epitaxially-grown on the semiconductor substrate so as to obtain a multilayered semiconductor layer22, which is constituted by: a contact layer24; a contact layer29; and a solar battery layer23including p-n junctions. The multilayered semiconductor layer22thus obtained preferably consists of epitaxial layers with small deformation. A thickness of the multilayered semiconductor layer22(i.e., a thickness of each of the resulting solar battery cells) is preferably not less than 0.5 μm; however, the thickness is preferably not more than 30 μm so as to ensure flexibility of the solar battery cells20. The multilayered semiconductor layer22can be a compound semiconductor layer, which is a multilayer film including the p-n junctions.

As an alternative, the multilayered semiconductor layer22can be formed by MBE (molecular beam epitaxy), MOCVD (metalorganic chemical vapor deposition), VPE (vapor phase epitaxy), or the like.

(2) Step of Forming Back Surface Electrode27on Non-Light Receiving Surface Side

A back surface electrode27is formed on a surface of the multilayered semiconductor layer22by a generally-used electrode forming method such as a vapor-deposition method. In order for the back surface electrode27to serve as a support of the multilayered semiconductor layer22, a thickness of the back surface electrode27is preferably not less than 1 μm. On the other hand, in order to prevent each of the solar battery cells20from warping due to a difference between thermal linear coefficients of expansion between the multilayered semiconductor layer22and the back surface electrode27, the thickness of the back surface electrode27is preferably not more than 8 μm. The back surface electrode27can be made from a conductive material such as silver (Ag).

(3) Step of Removing Semiconductor Substrate

The entire semiconductor substrate, or the entire semiconductor substrate and part of the multilayered semiconductor layer22, is/are removed by a generally-used etching method so as to cause the contact layer29to be exposed. As an alternative, the semiconductor substrate can be removed from the multilayered substrate layer22by an epitaxial lift-off method etc. This step includes formation of mesas, on which n-type electrodes25and p-type electrodes26are to be formed. First, masks are formed by a generally-used photolithographic method so as to cover only necessary parts of the solar battery layer23. Then, unnecessary parts of the solar battery layer23are removed by an etching method so that the contact layer24is partially exposed.

The etching method can be a dry etching method or a wet etching method. Note, however, that it is preferable to employ a selective etching method, in which the etching process substantially stops upon reaching a surface of a certain layer.

The n-type electrodes25and the p-type electrodes26are formed on a surface, of the solar battery layer23, which is on the light receiving surface side. The n-type electrodes25and the p-type electrodes26are formed by a generally-used electrode forming method such as a photolithographic method, a vapor-deposition method, a lift-off method, or a sintering method. The n-type electrodes25and the p-type electrodes26can be made from a conductive material such as silver (Ag). Either the n-type electrodes25or the p-type electrodes26can be formed first, or the n-type electrodes25and the p-type electrodes26can be formed concurrently.

(5) Step of Separating Solar Battery Cells20

From the board thus obtained through the above steps, necessary parts only are separated out as the solar battery cells20. The solar battery cells20can be separated out by (i) making a cut in a peripheral outline of each of the solar battery cells20by a dicing method or a scribing method, and then (ii) separating out the solar battery cells20by an expanding method or a breaking method.

The solar battery cells20are obtained through the above steps. Next, a step of forming the inter connectors on the obtained solar battery cells20is described below.

(6) Step of Connecting Inter Connectors

The inter connectors31are connected to the n-type electrodes25and the p-type electrodes26by a spot welding method. The inter connectors31can be made from a conductive material such as silver (Ag). Shape of each of the inter connectors31can be any shape, as long as the each of the inter connectors31can be drawn out of the peripheral outline of each of the solar battery cells20.

The following description discusses a solar battery module40of the present embodiment with reference toFIG. 8.FIG. 8illustrates the solar battery module40. (a) ofFIG. 8is a plan view. (b) ofFIG. 8is a cross-sectional view taken along line C-C′ of (a) ofFIG. 8.

The solar battery module40is constituted by: the solar battery cells20; the inter connectors31; bus sections32; flexible resin layers33a,33b, and33c; and a flexible resin film34.

As illustrated in (a) ofFIG. 8, the solar battery module40includes: five solar battery cells20electrically connected in series with one another via corresponding ones of the inter connectors31to form a string. Such a string constituted by a plurality of solar battery cells20electrically connected in series with one another is referred to as a solar battery string30.

Each end of the solar battery string30is connected with a corresponding one of the bus sections32via corresponding ones of the inter connectors31. The bus sections32are provided at both ends of the solar battery string30, and collect electric power. The solar battery module40includes three solar battery strings30, each of which is provided with the bus sections32.

Note here that, in the present invention, (i) the number of the solar battery cells20included in each of the solar battery strings30and (ii) the number of the solar battery strings30are not limited to those described above, and can be any numbers.

As illustrated in (b) ofFIG. 8, the solar battery strings30include a stack of (i) the flexible resin layers33a,33b, and33c, and (ii) the flexible resin film34. The flexible resin layer33cis provided on the light receiving surface side of the solar battery strings30. The flexible resin layer33a, the flexible resin film34, and the flexible resin layer33bare provided, on the non-light receiving surface side of the solar battery strings30, such that they are on top of one another in this order from the solar battery cells20toward the non-light receiving surface side.

The flexible resin layer33a, the flexible resin layer33b, and the flexible resin film34, which are provided on the non-light receiving surface side, have holes (first holes)38penetrating them. Through the holes38, the bus sections32are each partially exposed. The exposed parts of the bus sections32serve as a respective plurality of electrically-connecting means32a. The plurality of electrically-connecting means32aare on the non-light receiving surface side. Note here that, although one hole38is formed in each of the bus sections32in the present embodiment, two or more holes38can be formed in each of the bus sections32as long as mechanical strength can be kept.

According to this configuration, a plurality of solar battery modules40can be connected with each other via the plurality of electrically-connecting means32aso as to form a solar battery array. Since such a solar battery array is configured such that adjacent ones of the plurality of solar battery modules40are connected with each other without any member therebetween, the connection part between the adjacent ones of the plurality of battery modules40has improved flexibility.

(Production Method for Solar Battery Module40)

The following description discusses a production method for the solar battery module40with reference toFIGS. 4 through 8.FIGS. 4 through 7are views with reference to which to explain steps included in the production method for the solar battery module40.

First, five solar battery cells20are prepared. Then, inter connectors31are welded to the solar battery cells20by a spot welding method, via which inter connectors the solar battery cells20are electrically connected in series with one another (seeFIG. 4). In this way, a solar battery string30is formed.

Next, other inter connectors31are welded to both ends of the solar battery string30also by the spot welding method. The both ends of the solar battery string30are connected with the bus sections32via such inter connectors31. The bus sections32can be made from metal.

Then, as illustrated inFIG. 5, three solar battery strings30each having the bus sections32connected at its both ends are arranged in parallel with one another. According toFIG. 5, the rightmost one and the leftmost one of the solar battery strings30are arranged such that their n-type regions are on an upper side ofFIG. 5and their p-type regions are on a lower side ofFIG. 5. The midmost one of the solar battery strings30is arranged such that its n-type region is on the lower side ofFIG. 5and its p-type region is on the upper side ofFIG. 5. Note here that, the solar battery strings30can be arranged such that adjacent ones of the solar battery strings30have their n-type regions and p-type regions on opposite sides (e.g.,FIG. 5), or can be arranged such that all the solar battery strings30have their n-type regions and p-type regions on the same sides.

Then, the flexible resin layer33ais applied to the flexible resin film34, which has openings formed in areas corresponding to positions of the bus sections32. Thereafter, such a flexible resin film34is laminated to the solar battery strings30that are arranged in parallel with one another (seeFIG. 6). Note here that the flexible resin film34is laminated such that its openings are on the non-light receiving surface side of the solar battery cells20. In this way, a temporarily-jointed solar battery module36is obtained.

The flexible resin film34is preferably a polyimide film or a fluorine resin film. It is further preferable that front and back surfaces of the polyimide film or of the fluorine resin be subjected to a corona discharge treatment or be treated with a chemical agent etc. so that the front and back surfaces become easy to adhere. One specific example of such a film is KAPTON 100EN (manufactured by DU PONT-TORAY CO., LTD.) or the like, whose front and back surfaces have been subjected to the corona discharge treatment so that the surfaces become easy to adhere.

The flexible resin layers33a,33b, and33care preferably made from transparent flexible resin with high adhesiveness. Examples of such flexible resin encompass: epoxy resin, urethane resin, silicon resin, acrylic resin, and fluorine resin. Specific example of such flexible resin is DC93-500 (manufactured by Dow Corning Toray Co., Ltd).

Then, as illustrated inFIG. 7, the flexible resin layers33band33care applied to respective two exfoliate resin films37. Such two exfoliate resin films37are laminated to the light receiving surface side and the non-light receiving surface side of the temporally-joined solar battery module36, respectively.

The exfoliate films37serve as exfoliate paper. Each of the exfoliate films37is preferably a polyimide film or a fluorine resin film. A specific example of each of the exfoliate films37is KAPTON 200H (manufactured by DU PONT-TORAY CO., LTD.) or the like.

The laminating is carried out preferably with use of a generally-used lamination device under a condition where a heater temperature is a room temperature and a pressure is 0.02 MPa.

Then, as illustrated inFIG. 8, the two exfoliate films37are removed. Thereafter, parts of the flexible resin layers33aand33b, which parts correspond to positions of the openings in the flexible resin film34, are removed. In this way, each of the bus sections32is partially exposed to outside.

The flexible solar battery module40is obtained through the above steps.

A solar battery array41can be constituted by a plurality of the foregoing flexible solar battery modules40. The following description discusses the solar battery array41with reference toFIG. 1.FIG. 1illustrates the solar battery array41. (a) ofFIG. 1is a plan view. (b) ofFIG. 1is a cross-sectional view taken along line D-D′ of (a) ofFIG. 1. (c) ofFIG. 1is a cross-sectional view taken along line E-E′ of (a) ofFIG. 1.

The solar battery array41is constituted by three solar battery modules40connected with one another.

As illustrated in (a) ofFIG. 1, the solar battery strings30in each of the solar battery modules40are connected in series with one another via corresponding ones of wires43, which are connected with the bus sections32. Similarly, the three solar battery modules40in the solar battery array41are connected in series with one another via corresponding ones of the wires43. In this way, all the solar battery cells20included in the solar battery array41are electrically connected in series with one another. Note here that the wires43can be connected to the bus sections32by soldering.

According to this configuration, an electrical connection between adjacent ones of the solar battery modules40is made on the non-light receiving side of the solar battery array41. Therefore, there are no metal components such as the bus sections32between adjacent ones of the solar battery modules40connected with each other. Accordingly, flexibility of the connection part between the adjacent ones of the solar battery modules40is improved.

Further, as illustrated in (b) ofFIG. 1, the solar battery array41is configured such that adjacent ones of the solar battery modules40overlap each other at their neighboring ends, with their neighboring ends in contact with each other. The overlapped areas of the respective adjacent ones of the solar battery modules40are physically connected with each other with an adhesive agent42. The adhesive agent is not limited to a particular kind. A specific example of the adhesive agent is RTV-S691 (manufactured by WACKER ASAHIKASEI SILICONE CO., LTD.) or the like.

According to this configuration, the solar battery array41is configured such that the connection part between adjacent ones of the solar battery modules40is uniform in its physical structure. Accordingly, mechanical strength of the connection part is improved.

A second embodiment in accordance with the present invention is described below with reference toFIGS. 9 through 11. Note here that constituents corresponding to the constituents of Embodiment 1 are assigned identical referential numerals.

A solar battery module50of the present embodiment is described below with reference toFIG. 10.FIG. 10illustrates a solar battery module of a second embodiment in accordance with the present invention. (a) ofFIG. 10is a plan view. (b) ofFIG. 10is a cross-sectional view taken along line F-F′ of (a) ofFIG. 10.

The solar battery module50is different from the foregoing solar battery module40of Embodiment 1 mainly in terms of (i) the number of solar battery cells20and the number of solar battery strings30a, (ii) a laminated structure of flexible resin layers45aand45band flexible resin films46aand46b, which are laminated to the solar battery strings30a, and (iii) holes (second holes)48formed on the light receiving surface side. In view of this, the following description mainly discusses these differences.

As illustrated in (a) ofFIG. 10, the solar battery module50includes two solar battery strings30a. Each of the solar battery strings30aincludes three solar battery cells20. Note however that, in the present invention, the number of the solar battery cells20and the number of the solar battery strings30aare not limited to those described above, and can be any numbers depending on the situation.

As illustrated in (b) ofFIG. 10, the solar battery module50is configured such that the flexible resin layers45aand45band the flexible resin films46aand46bare laminated to the solar battery strings30a, each of which has its ends connected with respective bus sections32. The flexible resin layer45band the flexible resin film46bare provided such that they are on top of each other in this order from the solar battery cells20toward the light receiving surface side. The flexible resin layer45aand the flexible resin film46aare provided such that they are on top of each other in this order from the solar battery cells20toward the non-light receiving side. That is, both sides of the solar battery module50are protected by the flexible resin films46aand46b, respectively.

The solar battery module50has, on its non-light receiving surface side, holes47penetrating the flexible resin layer45aand the flexible resin film46a. The holes47are formed in areas corresponding to positions of the bus sections32. Further, the solar battery module50has, on its light receiving surface side, the holes48penetrating the flexible resin layer45band the flexible resin film46b. The holes48are formed in areas corresponding to the positions of the bus sections32. That is, part of each of the bus sections32is exposed through a corresponding one of the holes47and a corresponding one of the holes48on the non-light receiving surface side and on the light receiving side, respectively.

(Production Method for Solar Battery Module50)

The following description discusses a production method for the solar battery module50. The following description mainly discusses differences between the production method for the solar battery module50and that for the solar battery module40of Embodiment 1.

First, as illustrated inFIG. 9, two solar battery strings30aare prepared. The solar battery strings30aare arranged in the same way as in Embodiment 1.FIG. 9illustrates how the solar battery strings30aare arranged.

Next, the flexible resin layers45aand46bare applied to the flexible resin films46aand46b, respectively, by a roll coater method. Note here that the flexible resin films46aand46bhave, in advance, openings formed in areas corresponding to positions of the bus sections32.

Then, the flexible resin films46aand46b, to which the flexible resin layers45aand45bare applied, are laminated to the non-light receiving surface side and the light receiving surface side of the solar battery strings30ahaving the bus sections32connected thereto, respectively. The laminating is carried out preferably by a generally-used lamination device for terrestrial application, under a condition where a heater temperature is a room temperature and a pressure is 0.01 MPa.

Each of the flexible resin films46aand46bis preferably a resin film with high transparency and high heat resistance, unlike the flexible resin film34of Embodiment 1. Examples of such a resin film encompass a resin film made from: an ethylene tetrafluoride-ethylene copolymer, vinylidene fluoride resin, polytrifluorochloroethylene resin, acrylic resin, polytrifluorochloroethylene resin-coated acrylic resin, or polyester resin. A specific example of such a resin film is AFLEX 50NS (manufactured by ASAHI GLASS CO., LTD.) or the like.

Thereafter, parts of the flexible resin layer45a, which parts correspond to positions of the openings in the flexible resin film46a, are removed so that each of the bus sections32is partially exposed. Similarly, parts of the flexible resin layer45b, which parts correspond to positions of the openings in the flexible resin film46b, are removed so that each of the bus sections32is partially exposed.

The solar battery module50is obtained through the above steps.

A solar battery array51is constituted by a plurality of the foregoing solar battery modules40, and includes solar battery cells20which are electrically connected in series with one another. The following description discusses the solar battery array51with reference toFIG. 11.FIG. 11illustrates the solar battery array51. (a) ofFIG. 11is a plan view. (b) ofFIG. 11is a cross-sectional view taken along line G-G′ of (a) of FIG.11.

The solar battery array51of the present embodiment is different from the foregoing solar battery array41of Embodiment 1 mainly in that solar battery modules50are physically connected with one another with use of rivets.

Since flexible resin films46aand46beach having high strength are provided as outermost layers of each of the solar battery modules50, the rivets are suitable for physical connection between adjacent ones of the solar battery modules50that constitute the solar battery array51. Note, however, that the adjacent ones of the solar battery modules50are physically connected with each other not necessarily with use of the rivets, and therefore can be physically connected with each other by sewing.

Further, since the solar battery array51has holes47and holes48on its non-light receiving surface side and light receiving surface side, respectively, wires53can be welded to bus sections32by a spot welding method. The spot welding method is such that (i) electrodes are pressed to a surface of each of the bus sections32through a corresponding one of the holes47, which surface is right opposite to a corresponding one of a plurality of electrically-connecting means32a, and then (ii) an electrical current is applied between the electrodes. In this way, the wires53are welded to the plurality of electrically-connecting means32a.

It should be noted that the number of solar battery cells in each of the solar battery strings, the number of the solar battery strings in each of solar battery modules, and the number of the solar battery modules in the solar battery array are not limited to those described above, and can be any numbers depending on the situation. Further, positions of the solar battery modules constituting the solar battery array are not limited to those described above, and can be any positions depending on the situation.

As described so far, in order to attain the above object, a solar battery module in accordance with the present invention is a solar battery module for constituting a solar battery array, including: at least one solar battery string that is constituted by a plurality of solar battery cells electrically connected in series with each other; bus sections electrically connected with respective endmost ones of the plurality of solar battery cells that constitute said at least one solar battery string; and at least one flexible resin layer provided on each of both sides, which are a first side and a second side, of the solar battery module so as to sandwich said at least one solar battery string and the bus sections, the first side of the both sides of the solar battery module having first holes, through which the bus sections are each partially exposed, and the bus sections having areas which are exposed through the respective first holes, the areas serving as a respective plurality of electrically-connecting means.

A plurality of solar battery modules in accordance with the present invention are to constitute a solar battery array by being electrically connected with each other. In a case where each of the plurality of the solar battery modules is constituted by a flexible material, the each of the plurality of the solar battery modules is used as a flexible solar battery sheet. Accordingly, the solar battery array constituted by the plurality of solar battery modules is used as a flexible solar battery sheet array.

The plurality of solar battery modules in accordance with the present invention are electrically connected with each other via the plurality of electrically-connecting means of the bus sections. Note here that the plurality of electrically-connecting means of the bus sections can be connected with a wire by soldering etc. According to this configuration, the plurality of solar battery modules can be connected with each other via the wire. The bus sections are connected with respective endmost ones of the plurality of solar battery cells connected with each other, and collect electric power. Generally, the bus sections are made from metal.

According to this configuration, the plurality of electrically-connecting means of the bus sections are exposed through the respective first holes. Therefore, each of the bus sections is configured such that it does not protrude from the at least one flexible resin layer. Accordingly, there are no other members (e.g., the bus sections) between adjacent ones of the plurality of solar battery modules when the plurality of solar battery modules are electrically connected with each other. This makes it possible to achieve an advantage that the connected plurality of solar battery modules as a whole maintains its flexibility and keeps its mechanical strength uniform.

The solar battery module in accordance with the present invention is preferably configured such that: a number of said at least one solar battery string is two or more; and the two or more solar battery strings are electrically connected in series with each other via corresponding ones of the plurality of electrically-connecting means.

According to this configuration, the two or more solar battery strings in the solar battery module are connected with each other via the plurality of electrically-connecting means of the respective bus sections, which are at both ends of the two or more solar battery strings. Accordingly, it is possible to downsize each of the bus sections of the solar battery module in accordance with the present invention, as compared with a conventional configuration in which each of some of the bus sections belongs to two or more solar battery strings. This makes it possible to improve flexibility of the solar battery module.

Further, the two or more solar battery strings in the solar battery module can be connected with each other via the wire, which is connected with corresponding ones of the plurality of electrically-connecting means of the bus sections. In this way, the two or more battery strings are electrically connected in series with each other easily.

The solar battery module in accordance with the present invention is preferably configured such that: light receiving surfaces of the respective plurality of solar battery cells are situated on the second side; and the plurality of electrically-connecting means are on the first side.

Generally, the light receiving surfaces of the plurality of solar battery cells, which surfaces receive sunlight, are on one of both sides of the solar battery module. In this regard, according to the above configuration, an electrical connection between a plurality of solar battery modules is made on the other one of the both sides of each of the plurality of solar battery modules, i.e., on a side on which surfaces opposite to the light receiving surfaces of the plurality of solar battery cells are situated. This makes it possible to connect the plurality of solar battery modules in accordance with the present invention without affecting electric power generation by the plurality of solar battery cells. Particularly, in a case where the plurality of electrically-connecting means of the bus sections are connected with each other via the wire, the wire does not shield the light receiving surfaces of the plurality of solar battery cells against sunlight. Accordingly, the wire can be freely drawn.

It is preferable that the solar battery module in accordance with the present invention be configured such that: the second side having second holes so as to correspond to positions of the respective first holes, through which second holes the bus sections are each partially exposed.

According to this configuration, part, of each of the bus sections, which is right opposite to a corresponding one of the plurality of electrically-connecting means, is exposed. That is, the part of each of the bus sections is exposed on both sides of the solar battery module. Accordingly, the wire can be welded to corresponding ones of the plurality of electrically-connecting means of the bus sections by parallel gap welding, which is more definite method than soldering.

Specifically, first, the wire is placed on a corresponding one of the plurality of electrically-connecting means through a corresponding one of the first holes. Next, parallel gap electrodes are pressed to the corresponding one of the plurality of electrically-connecting means through a corresponding one of the second holes. Then, an electrical current is applied between the parallel gap electrodes. In this way, it is possible to weld the wire to corresponding ones of the plurality of electrically-connecting means.

The solar battery module in accordance with the present invention can further include: a flexible resin film provided on the first side which is the opposite side of the second side on which light receiving surfaces of the respective plurality of solar battery cells are situated, the flexible resin film being provided between said at least one solar battery string and said at least one flexible resin layer. Alternatively, the solar battery module in accordance with the present invention can further include: a flexible resin film provided on both of the first side and the second side of the solar battery module so as to cover said at least one flexible resin layer.

Generally, a flexible resin film is greater in strength than a flexible resin layer. According to the above configuration, since the flexible resin film is included in the solar battery module, the solar battery module has high strength. Accordingly, the solar battery module keeps its strength even if a thickness of the entire solar battery module is reduced.

Further, according to the configuration in which the flexible resin films are provided on both sides of the solar battery module, outer surfaces of the solar battery module are increased in their strength. Accordingly, a rivet etc. can be easily used for physically connecting a plurality of solar battery modules so as to form a solar battery array.

A solar battery array in accordance with the present invention includes: a plurality of the foregoing solar battery modules, the plurality of solar battery modules being electrically connected in series with each other via corresponding ones of the plurality of electrically-connecting means, each of which serves as an end of an electrical connection in a corresponding one of the plurality of solar battery modules.

According to this configuration, it is possible to easily produce a large-scale solar battery array in accordance with the present invention by connecting the plurality of solar battery modules. In addition, according to the solar battery array in accordance with the present invention, it is possible to improve flexibility of the entire solar battery array because there are no members such as the bus sections between adjacent ones of the plurality of solar battery modules.

The solar battery array in accordance with the present invention can be configured such that: the plurality of solar battery modules are arranged such that adjacent ones of the plurality of solar battery modules overlap each other at their neighboring ends; and said neighboring ends are physically connected with each other by bonding, sewing, or a rivet.

According to this configuration, easy methods such as bonding, sewing, or the rivet can be used for physically connecting the plurality of solar battery modules. Therefore, it is possible to produce a large-scale solar battery array at low cost. Further, since the connection part between adjacent ones of the plurality of solar battery modules is uniform in its physical structure, mechanical strength of the solar battery array as a whole is improved.

The solar battery array in accordance with the present invention can further include: a wire connected with corresponding ones of the plurality of electrically-connecting means, the two or more of solar battery strings being electrically connected in series with each other via the corresponding ones of the plurality of electrically-connecting means and the wire.

The invention is not limited to the description of the embodiments above, but may be altered 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 invention.

INDUSTRIAL APPLICABILITY

The present invention is suitably applicable to a constituent unit of a large-scale solar battery sheet. The present invention can be employed in for example a solar battery for space application (i.e., a solar battery for an artificial satellite) or the like.

REFERENCE SIGNS LIST