JP2009043872A - Solar cell module, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a solar cell module and a manufacturing method of the structure, which can manufacture a photoelectric conversion device with a sufficient yield even if the film thickness of a semiconductor layer constituting a solar cell is very thin. <P>SOLUTION: The module is provided with a solar cell array formed by connecting a solar cell string consisting of a plurality of solar cells 6 which are electrically connected by interconnectors 5 to bus bars 7, a transparent silicone resin 3 which is formed and laminated to cover whole upper and lower faces of the solar cell array and to include the solar cell array, and a flexible transparent cover board 4 formed just above the transparent silicone resin 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solar cell module and a manufacturing method thereof, and more specifically to a flexible solar cell module for space using a single crystal semiconductor solar cell and a manufacturing method thereof.

  As a conventional technique, a solar cell module as shown in FIG. 9 is disclosed in, for example, Patent Document 1 below. 9A is a plan view of the photoelectric conversion device, FIG. 9B is a cross-sectional view of the photoelectric conversion device IXb-IXb, and FIG. 9C is a cross-sectional view of the photoelectric conversion device IXc-IXc. As shown in FIG. 9, this conventional solar cell module includes a single substrate 101, a plurality of solar cells 103 arranged in a plane on the substrate 101 and bonded by silicon resin 102, and a plurality of solar cells 103. An interconnector 104 that is a connecting member for electrically connecting the solar cells 103 and a single transparent cover plate 105 that covers the solar cells 103 and the interconnector 104 are provided. The transparent cover plate 105 is bonded to the solar battery cell 103 and the interconnector 104 with a transparent silicon resin 106. Further, in the solar cell 103, a front electrode 112 is formed on the main surface of the single crystal semiconductor substrate 111 that receives sunlight, and a back electrode 113 is formed on the opposite main surface.

  However, in the above-described conventional technique, the single crystal semiconductor substrate 111 is formed with an ultra-thin single crystal semiconductor layer having a thickness of 50 μm or less and the upper portion thereof is covered with a flexible transparent cover plate 105. In the case of a solar cell module, it has been found that the method described in Patent Document 1 is difficult to manufacture and causes new problems.

  Specifically, in the solar cell module manufactured by the conventional technique shown in FIG. 9, the transparent silicon resin 106 is only on the light receiving surface side of the solar cell 103 as shown in FIGS. Is formed. Therefore, there is an in-plane distribution of the thickness of the transparent silicon resin 106. For example, in the IXb-IXb cross section shown in FIG. 9B and the IXc-IXc cross section shown in FIG. The distribution of height is greatly different. In particular, in the IXc-IXc cross section shown in FIG. 9C, there is a region where the transparent silicon resin 106 is not formed immediately below the transparent cover plate 105.

  For example, when a single crystal semiconductor layer having a thickness of 50 μm or more is formed on the single crystal semiconductor substrate 111 or when the transparent cover plate 105 having a sufficiently thick thickness of 100 μm or more is provided, the semiconductor layer or the flexible transparent cover Since the plate 105 has enough room to absorb the stress caused by the variation in the resin thickness, there is no problem. However, in the case of an ultra-thin flexible solar cell module in which the transparent cover plate 105 is 100 μm or less, since the mechanical strength of the transparent cover plate 105 is weak, it is caused by stress caused by the variation in the thickness of the transparent silicon resin 106. A wrinkle is generated in the transparent cover plate 105. Since the effective light receiving area is reduced by the defect, the photoelectric conversion characteristics of the solar cell module are deteriorated.

  Similarly, in the case of an ultra-thin flexible solar cell module in which a single crystal semiconductor layer having a single crystal semiconductor layer thickness of 50 μm or less is formed, the mechanical strength of the single crystal semiconductor is weak, so that the thickness of the silicon resin 102 varies. The single crystal semiconductor layer is wrinkled by the stress caused by. As a result, the effective light receiving area decreases, and the photoelectric conversion characteristics of the solar cell module deteriorate.

  Further, in a thin film solar cell using an amorphous silicon semiconductor or a microcrystalline silicon semiconductor, an example in which an ethylene vinyl acetate copolymer (EVA) is used instead of the above-described conventional silicon resin is disclosed in, for example, Patent Document 2 below. Is disclosed. The ethylene vinyl acetate copolymer disclosed in Patent Document 2 has a thick film thickness of 400 μm. If it is amorphous or microcrystalline, even if an ethylene vinyl acetate copolymer with a thickness of 400 μm is used, its flexibility is not hindered. However, when a single crystal semiconductor is laminated, it is extremely flexible. Sex is inhibited.

In general, it is difficult to reduce the thickness of an ethylene vinyl acetate copolymer, and the current technology limits the thinning to about 200 μm. In addition, in resins such as an ethylene vinyl acetate copolymer whose viscosity decreases only when heated at 100 ° C. or higher, the linear expansion coefficient of the ethylene vinyl acetate copolymer (on the order of 10 ⁻⁴ / ° C.) and the linear expansion coefficient of the semiconductor ( ^Warpage occurs because it is very different from 10 ⁻⁶ / ° C.). For this reason, it cannot be used for a flexible solar cell module using an ultra-thin single crystal semiconductor. In addition, ethylene vinyl acetate copolymer is not suitable as a material for space because it is yellowed by ultraviolet rays.

Therefore, in the conventional method as described above, an ultra-thin flexible single crystal semiconductor solar cell module having a layer thickness of 50 μm or less and a thickness of the flexible transparent cover plate 105 of 100 μm or less is excellent. There was a problem that it was difficult to manufacture while maintaining the characteristics.
JP 2000-307143 A JP 2004-55970 A

  The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to provide a photoelectric conversion device that is a very thin film having a semiconductor layer thickness of 50 μm or less. It is an object of the present invention to provide a method that can be manufactured with high yield and a structure of such a photoelectric conversion device.

  The solar cell module of the present invention that achieves the above object includes a solar cell array formed by connecting a solar cell string including a plurality of solar cells electrically connected by an interconnector to a bus bar, and a solar cell array A transparent silicon resin and a flexible transparent cover plate formed immediately above the transparent silicon resin are provided so as to cover the entire upper and lower surfaces and to be laminated so as to enclose the solar cell array.

  In one embodiment of the solar cell module of the present invention, the transparent silicon resin is formed on the silicon resin formed directly on the substrate.

  In preferable embodiment of the solar cell module of this invention, the thickness of a flexible transparent cover board is 100 micrometers or less, and the layer thickness of the single crystal semiconductor layer which comprises a photovoltaic cell is 50 micrometers or less. The viscosity of the silicon resin and the transparent silicone resin at room temperature is preferably 2,000 mPa · s or more and 100,000 mPa · s or less. Furthermore, the film thickness of the transparent silicon resin is not less than the sum of the thickness of the single crystal semiconductor layer of the solar battery cell and the thickness of the interconnector, and is preferably not more than 75 μm.

  The manufacturing method of the solar cell module of the present invention includes a step of arranging a plurality of solar cells in series and electrically connecting electrodes of adjacent solar cells among the plurality of solar cells by an interconnector. A step of forming a solar cell string, a step of forming a solar cell array by connecting a plurality of formed solar cell strings to a bus bar, a solar cell array on a transparent silicon resin, and another transparent A step of stacking the silicon resin on the solar cell array, a step of laminating the solar cell array placed on the transparent silicon resin and overlaying the transparent silicon resin from above in a vacuum, and a transparent silicon resin Heating and curing.

  In one embodiment of the method for manufacturing a solar cell module of the present invention, after the step of applying the laminate, before the step of heating and curing the transparent silicon resin, the bubbles contained in the laminated solar cell module are removed. A step of removing is further provided.

  According to the present invention, since no wrinkles enter the flexible transparent cover plate, it is possible to prevent the effective light receiving area from decreasing. As a result, a solar cell module structure that does not deteriorate the photoelectric conversion characteristics of the solar cell module is realized, and such a solar cell module can be manufactured with a good yield. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of a solar cell module of the present invention, in which (a) is a plan view of the solar cell module viewed from the light receiving surface, and (b) is a cross-sectional view taken along line Ib-Ib in (a). FIG.

  As shown in FIG. 1, in the solar cell module of the present invention, the silicon resin 2 is formed on almost the entire surface of the substrate 1 and immediately above it. A transparent silicon resin 3 is formed on almost the entire surface of the silicon resin 2, and a flexible transparent cover plate 4 is formed on the almost entire surface of the transparent resin 3. The plurality of solar cells 6 including a single crystal semiconductor connected by the interconnector 5 are encapsulated in the transparent silicon resin 3 except for the external connection portions 8 of the bus bars 7 of the solar cells 6.

  Since the plurality of solar cells 6 connected by the interconnector 5 are included in the transparent silicon resin 3 except for the external connection portion 8 of the bus bar 7 connected from the solar cells 6 via the interconnector 5. Silicon resin 2 and transparent silicon resin 3 are uniformly formed on almost the entire surface of the solar cell module. Therefore, there are no irregularities on the surfaces of the silicon resin 2 and the transparent silicon resin 3, and no wrinkles occur on the transparent cover plate 4. Therefore, the effective light receiving area does not decrease, and the photoelectric conversion characteristics of the solar cell module do not deteriorate.

  In this Embodiment, the flexible transparent cover board 4 is 100 micrometers or less, and the layer thickness of the single crystal semiconductor layer 11 of the photovoltaic cell 6 is 50 micrometers or less. Such a plurality of solar cells 6 connected by the interconnector 5 that are weak in mechanical strength and easily damaged are mostly contained in the transparent silicon resin 3, and therefore may be damaged in the subsequent manufacturing process. Since the work can be performed without directly touching a certain place, it can be manufactured with a high yield.

  In the solar cell module of the present embodiment, the viscosity of the silicon resin and the transparent silicon resin at room temperature is not less than 2,000 mPa · s and not more than 100,000 mPa · s. If the viscosity of the silicon resin and the transparent silicone resin at room temperature is not 2,000 mPa · s or more, it is difficult to obtain a required film thickness, and bubbles are likely to enter. The appearance of bubbles not only deteriorates the appearance, but also may damage the solar cell in an environment such as outer space. Further, if the viscosity at room temperature is not 100,000 mPa · s or less, it is difficult to remove bubbles in the resin with a vacuum laminator or the like, which causes bubbles to enter.

  The viscosity of the silicone resin and the transparent silicone resin at room temperature is from 2,000 mPa · s to 100,000 mPa · s, and a solar cell with good appearance can be formed with high yield without bubbles. In addition, when a resin capable of obtaining such a viscosity at a high temperature of about 100 ° C. is used, warpage occurs in the obtained solar cell module because the linear expansion coefficient of the resin and the linear expansion coefficient of the semiconductor are generally greatly different. However, handling becomes difficult.

  Moreover, the film thickness of the transparent silicon resin of this Embodiment is more than the sum of the thickness of the single crystal semiconductor layer of a photovoltaic cell, and the thickness of an interconnector, and is 75 micrometers or less. If the maximum film thickness in the plane of the transparent silicon resin is not equal to or greater than the sum of the thickness of the single crystal semiconductor layer and the thickness of the interconnector, a resin gap is generated and bubbles are generated. Further, by setting the maximum film thickness in the plane of the transparent silicon resin to 75 μm or less, for example, in a temperature cycle test from −198 ° C. to 150 ° C., the flexible transparent cover plate 4 is wavy after the test. Can be prevented.

  As shown in FIG. 1, in the solar cell module according to the present embodiment, a silicon resin 2 is formed on almost the entire surface of the substrate 1 and a transparent silicon resin 3 is formed on the almost entire surface of the silicon resin 2. . In addition, a flexible transparent cover plate 4 is formed on almost the entire surface of the transparent silicon resin 3 and immediately above the plurality of solar cells 6 connected by the interconnector 5 except for the external connection portion 8 of the bus bar 7. It is included in the transparent silicone resin 3. Therefore, since the silicon resin 2 and the transparent silicon resin 3 are uniformly formed on almost the entire surface of the solar cell module, there is no unevenness in the expressions of the silicon resin 2 and the transparent silicon resin 3, and a flexible transparent cover plate There is no trap in 4 Therefore, since the effective light receiving area does not decrease, the photoelectric conversion characteristics of the solar cell module do not deteriorate.

  Next, the manufacturing method of the solar cell module of embodiment of this invention is demonstrated using FIGS. FIGS. 2-4 is the top view and schematic sectional drawing which show the manufacturing process of the solar cell module of this invention.

  First, a plurality of solar cells 6 as shown in FIGS. 2A and 2B are prepared. The solar battery cell 6 includes a front electrode 10, a semiconductor layer 11, and a back electrode 12, and a mesa (not shown), an antireflection film (not shown), and the like are appropriately formed.

  In the present embodiment, the solar battery cell 6 includes a single crystal semiconductor layer including a pn junction as the semiconductor layer 11. If necessary, it may be a semiconductor layer composed of a multilayer film including a pn junction. The semiconductor layer 11 that can be used in the present embodiment is not limited to a specific material, and a known layer can be used depending on the application. Examples of materials applicable as the semiconductor layer 11 include Si, Ge, GaAs, InP, InGaP, and InGaAs. Further, the semiconductor layer 11 is preferably an epitaxial layer with a small strain in order to remove all or part of the semiconductor substrate.

  In the present invention, the semiconductor layer 11 can be laminated by epitaxial growth as described above, and as its method, MBE method, MOCVD method, VPE method, or the like can be used. Further, the semiconductor layer 11 preferably has a layer thickness of 2 μm or more and 50 μm or less for use as a solar cell. If the thickness is less than 2 μm, light absorption is insufficient, and thus the photoelectric conversion efficiency may be deteriorated. There is a problem that the photoelectric conversion efficiency per unit deteriorates. The thickness of the semiconductor layer 11 is more preferably 3 μm or more and 20 μm or less.

  Next, a process of forming the back electrode 12 on the surface opposite to the light receiving surface of the semiconductor layer 11 will be described. Specifically, after an electrode is formed by a normal vapor deposition method or a sputtering method, the electrode is brought into close contact with the back surface of the semiconductor layer 11 by a sintering method or the like. In addition, other ordinary electrode forming methods can be used. In the present invention, a material that can be used for the surface electrode is not particularly limited, and those known in the art can be used. As an example, a conductive material made of silver (Ag) can be given.

  Next, the process of forming the surface electrode 10 on the main surface of the semiconductor layer 11 will be described. Specifically, the surface electrode 10 is formed on the semiconductor layer by, for example, a normal photolithography method, a vapor deposition method, a lift-off method, or a sintering method. In addition, other ordinary electrode forming methods can be used. In the present invention, the material that can be used for the surface electrode is not particularly limited, and those known in the art can be used. For example, a conductive material made of silver (Ag) can be given as an example.

  Here, it is preferable that the surface electrode 10 has a comb shape as shown in FIG. 1A. However, in the present invention, the surface electrode 10 is not limited to the comb shape, and all other functions capable of functioning as a photoelectric conversion device. An electrode shape can be employed. In addition, a known method can be used as a method of forming a surface electrode such as a comb shape. Specifically, the semiconductor layer is etched into a desired shape through a mask, and the surface electrode is applied to the etched portion. The method of forming etc. is mentioned. Thereafter, a mesa (not shown) and an antireflection film (not shown) are formed to complete the solar battery cell 6.

Next, as shown in FIG. 3, the interconnector 5 is welded to the pad portions on the surface electrodes 10 of the plurality of solar cells 6 using a parallel gap welder. The interconnector 5 is preferably provided with stress relief, and the interconnector material is more preferably silver or silver added with a small amount of impurities. The thickness of the interconnector is preferably 10 μm or more and 30 μm or less. If it is 10 μm or more, the strength as an interconnector can be sufficiently maintained, and if it is not 30 μm or less, it cannot be completely encapsulated with silicon resin, causing bubbles. If necessary, one bypass diode (not shown) is simultaneously welded to one solar battery cell 6 in parallel gap. Area of the bypass diode is preferably 5 mm ² or more 80 mm ² or less, if it is less than 5 mm ^2, the heat generation of the diode reliability problems become more 0.99 ° C. when the bypass function is activated. When the area of the bypass diode is larger than 80 mm ² , the flexibility of the solar cell module is hindered. The thickness of the diode is preferably 10 μm or more and 60 μm or less. When the thickness of the diode is less than 10 μm, the manufacturing yield is rapidly deteriorated, and the cost of the diode is rapidly increased. On the other hand, if it is thicker than 60 μm, there is a problem that the resin does not completely enclose the diode and bubbles tend to remain.

  Next, the solar cell 6 to which the interconnector 5 is welded is welded to an electrode having a polarity different from that of the surface electrode 10 at the end of the other adjacent interconnector 5 by using a parallel gap welding machine to form a string. To do. At this time, as shown in FIG. 3, when the electrode having the polarity different from that of the surface electrode 10 is only the back electrode 12, the electrode is welded to the back electrode 12, but the electrode having the polarity different from that of the surface electrode 10 is on the light receiving surface side. May be welded to electrodes having different polarities on the light receiving surface side.

  Next, the strings produced as shown in FIG. 3C are connected in series or in parallel by the bus bar 7 to produce an array. As the bus bar material, silver or silver added with a small amount of impurities is more preferable. The thickness of the bus bar is preferably 10 μm or more and 50 μm or less. If it is 10 μm or more, the strength as an interconnector can be sufficiently maintained, and if it is thicker than 50 μm, there is a problem that the resin cannot completely enclose the bus bar and air bubbles tend to remain.

  Next, as shown in FIG. 4, on the other hand, a transparent silicon resin 3 is formed on the release film 13, and an array in which strings are connected by bus bars is installed. Similarly, the transparent silicon resin 3 is formed on the flexible transparent cover plate 4, and the flexible transparent cover plate 4 is overlaid so that the transparent silicon resin 3 is on the array as shown in FIG.

  As a material constituting the flexible transparent cover plate 4, tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene-ethylene copolymer resin (ETFE), or biaxially stretched polyethylene naphthalate resin (PEN) is desirable. Further, it is more preferable that AlOx and SiOx are formed on the light receiving surface (light receiving side) of these resins constituting the flexible transparent cover plate 4. Further, it is desirable that the back surface (cell side) is subjected to a treatment for increasing the affinity with other resins, for example, a corona discharge treatment. Tetrafluoroethylene-hexafluoropropylene copolymer resin and tetrafluoroethylene-ethylene copolymer resin have high visible light transmittance, and visible light even when exposed to space radiation such as ultraviolet rays, electron beams, and proton beams. The transmittance of is not reduced. In addition, by coating AlOx film or SiOx film on the surface of tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-ethylene copolymer resin, or biaxially stretched polyethylene naphthalate resin (PEN) It was confirmed that the transmittance of the resin hardly decreased even when exposed to oxygen.

  Thus, in space solar cell modules, AlOx film, SiOx film coating, uncoated tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-ethylene copolymer resin, or biaxial stretching It is particularly desirable to use polyethylene naphthalate resin (PEN) or the like. In the case of tetrafluoroethylene-hexafluoropropylene copolymer resin, the film thickness is desirably 25 μm or more and 100 μm or less. If it is 25 μm or more, the proton beam is sufficiently decelerated in the tetrafluoroethylene-hexafluoropropylene copolymer resin, stays in the tetrafluoroethylene-hexafluoropropylene copolymer resin, and does not adversely affect the solar battery cell. On the other hand, when the thickness is 100 μm or more, the flexibility of the resin becomes poor and the flexibility of the solar cell module becomes poor. In the case of a tetrafluoroethylene-ethylene copolymer resin, it is preferably 30 μm or more and 100 μm or less. If it is 30 μm or more, the proton beam is sufficiently decelerated in the tetrafluoroethylene-ethylene copolymer resin and stays in the tetrafluoroethylene-ethylene copolymer resin and does not adversely affect the solar battery cell. On the other hand, when the thickness is 100 μm or more, the flexibility of the resin becomes poor, and the flexibility of the solar cell module becomes poor. In the case of a biaxially stretched polyethylene naphthalate resin, it is preferably 50 μm or more and 100 μm or less. If it is 50 μm or more, the proton beam is sufficiently decelerated in the tetrafluoroethylene-ethylene copolymer resin and stays in the tetrafluoroethylene-ethylene copolymer resin and does not adversely affect the solar cell. On the other hand, when the thickness is 100 μm or more, the flexibility of the resin becomes poor, and the flexibility of the solar cell module becomes poor.

  The transparent silicone resin preferably has a viscosity of 2,000 mPa · s to 100,000 mPa · s. If the viscosity of the transparent silicone resin at room temperature is not 2,000 mPa · s or more, it is difficult to obtain a necessary film thickness, and it is difficult to enclose an object to be included, and bubbles are likely to enter. Further, if the viscosity at room temperature is not 100,000 mPa · s or less, it becomes difficult to remove bubbles in the resin with a vacuum laminator or the like, which causes bubbles to enter. In particular, in the case of a solar cell module for space use, silicon resin with less degas is required, and specific products satisfying the above include DC93-500 manufactured by DOW-CORNING, CV-2500 manufactured by NuSil, and the like.

  Next, the solar cell array formed on the transparent silicon resin 3 and laminated with the transparent silicon resin 3 from above is laminated in a vacuum using a vacuum laminating apparatus, whereby the structure shown in FIG. 5 is obtained. It is formed. Thereafter, further, air bubbles between the flexible transparent cover plate 4 and the transparent silicon resin 3, air bubbles between the release film 13 and the transparent silicon resin 3, and between the solar battery cell 6 and the transparent silicon resin 3. Air bubbles, bubbles between the transparent silicone resins 3, bubbles in the transparent silicone resin 3 are almost all removed. Thereafter, curing is performed at room temperature for 3 days, and heat curing is performed at 120 ° C. for 60 minutes to cure the transparent silicon resin 3.

  As the vacuum laminating apparatus used here, an apparatus provided with two upper and lower vacuum chambers partitioned by a diaphragm rubber sheet and capable of being vacuum-pressed is preferable. In addition, the vacuum press is preferably realized by evacuating the upper and lower chambers to 133 Pa and returning only the upper chamber to atmospheric pressure over a period of 1 minute or longer. If the atmospheric pressure is suddenly applied only to the upper chamber, bubbles are generated.

  At this time, the thickness of the transparent silicon resin formed on the flexible transparent cover plate 4 is preferably not less than the sum of the thickness of the single crystal semiconductor layer and the thickness of the interconnector and not more than 75 μm. This film thickness can be controlled by the thickness of the transparent silicon resin 3 formed on the flexible cover plate 4 or the release film 13 and the pressure of the vacuum press. If the thickness of the transparent silicon resin is not more than the sum of the thickness of the single crystal semiconductor layer and the thickness of the interconnector, the solar cells and the interconnector cannot be completely encapsulated with the resin, causing bubbles. Moreover, if it is not 100 micrometers or less, resin will become thick too much and the flexibility of a solar cell module will be impaired. A fluororesin such as ETFE or FEP can be used as the release film.

  Next, as shown in FIG. 6A, a silicon resin 2 is formed on the substrate 1. Next, the release film 13 of the array laminated with the transparent silicon resin 3 shown in FIG. 5 is peeled off, the flexible transparent cover plate 4 is turned up, and as shown in FIG. Install on top. Thereafter, laminating is performed in a vacuum using a vacuum laminating apparatus, and almost all the bubbles are removed, whereby the solar cell module shown in FIG. 1 is formed.

  The silicone resin preferably has a viscosity of 100,000 mPa · s or less. If the viscosity of the silicone resin at room temperature is not more than 2,000 mPa · s, it is difficult to obtain the required film thickness, and bubbles cannot easily be contained because the objects to be included cannot be included. If the viscosity at room temperature is not 100,000 mPa · s or less, it is difficult to remove bubbles in the resin with a vacuum laminator or the like, which causes bubbles to enter. In particular, in the case of a solar cell module for space use, a silicon resin with less degas is required, and as a specific product that satisfies the above, there is RTV-S691 manufactured by WACKER-CHEMIE.

  A temperature cycle test of −198 ° C. to 150 ° C. was performed on the solar cell array shown in FIG. The thickness of the transparent silicon resin 3 was taken as a parameter. The measured value was the rate of change from the initial value of the short-circuit current value of the solar cell array. FIG. 7 shows a graph of the results when the holding time at −198 ° C. and 150 ° C. is 1 minute or more and the cycle number is 100 times. All the solar cells have two GaInP / GaAs junctions, and the thickness of the semiconductor layer was about 5.0 μm. The interconnector was made of silver added with magnesium as a small amount of impurities, the thickness was 15 μm, and the bus bar was also made of the same material and the thickness was 30 μm. As the silicone resin, RTV-S691 manufactured by WACKER-CHEMIE was used, the thickness thereof was 75 μm, and a Kapton film 300EN made by Toray DuPont having a thickness of 75 μm was used as the substrate.

  From the graph shown in FIG. 7, it can be seen that the rate of change in the short-circuit current after the test decreases with the transparent silicon resin thickness in the vicinity of 75 μm as the boundary. When the thickness of the transparent silicon resin exceeds 75 μm, it was found that a wavy ridge as shown in FIG. 8 entered the flexible transparent cover plate, and the solar cell was also deformed into a wavy shape. It is considered that the wrinkle like this wave reduces the effective light receiving area and the short circuit current. In addition, it is considered that the cause of wrinkles is that the flexibility of the solar cell module suddenly decreases and the rigidity increases with the transparent silicon resin thickness of 75 μm as a boundary.

  As an example, a solar cell module using a single crystal semiconductor solar cell as shown in FIG. 1 was produced. First, as shown in FIG. 2, a multilayer semiconductor layer 11 was epitaxially grown on a semiconductor substrate (not shown) using a Ge material by a metal organic chemical vapor deposition (MOCVD) method. Here, the multilayer semiconductor layer 11 is a p-type GaAs layer having a thickness of 1 μm and an n-type GaAs layer having a thickness of 3 μm. In the case where the photoelectric conversion device functions as a solar cell, the semiconductor layer 11 may have a total film thickness of 2 μm or more. Next, a surface electrode 10 mainly composed of silver (Ag) was formed on the main surface of the multilayer semiconductor layer 11 by combining a conventionally known photolithography method, vapor deposition step method, lift-off method, and heat treatment.

Next, unnecessary multilayer semiconductor layer 11 is removed by etching using a wet etching method to form a mesa (not shown), an antireflection film made of AlO _x / TiO _{x is} formed by a vapor deposition method, and heat treatment is performed. To adhere. As an etchant, a mixed aqueous solution of citric acid and hydrogen peroxide was used.

  Next, as shown in FIG. 3, an interconnector 5 with a stress relief made of silver in which a small amount of magnesium having a thickness of 12.5 μm is added as an impurity to the pad portion of the surface electrode 10 on the plurality of solar cells 6. Weld using a parallel gap welder. Next, the solar battery cell 6 to which the interconnector 5 is welded is welded to the back electrode 12 having a polarity different from that of the front electrode at the other end of the interconnector by using a parallel gap welder to form a string.

  Next, as shown in FIG. 4, a DC93-500 transparent silicon resin 3 made by DOW-CORNING is applied onto a release film 13 made of tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) having a thickness of 100 μm. An array is formed and strings are connected by bus bars. On the other hand, DC93-500 transparent silicon resin 3 made by DOW-CORNING was similarly formed on a flexible transparent cover plate 4 made of tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), as shown in FIG. As described above, the flexible transparent cover plate 4 is overlaid so that the transparent silicon resin is placed on the array.

  Next, a DC93-500 transparent silicon resin 3 manufactured by DOW-CORNING was formed on the tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) release film 13, and an array was placed. Hexafluoropropylene copolymer (FEP) Flexible transparent cover plate 4 is laminated with a DC93-500 transparent silicon resin 3 made by DOW-CORNING and laminated in a vacuum using a vacuum laminator. Remove almost all the bubbles. Thereafter, curing is performed at room temperature for 3 days, and heat curing is performed at 120 ° C. for 60 minutes to cure DC93-500 transparent silicon resin 3 manufactured by DOW-CORNING.

  Next, as shown in FIG. 6, first, an RTV-S691 silicon resin 2 made of WACKER-CHEMIE having a thickness of 75 μm is formed on a Kapton substrate 1 having a thickness of 75 μm. Next, the release film 13 of the array laminated with the transparent silicon resin 3 shown in FIG. 5 is peeled off and placed on the silicon resin 2 with the flexible transparent cover plate 4 facing up. Thereafter, laminating is performed in a vacuum using a vacuum laminating apparatus, and almost all bubbles are removed to produce the solar cell module shown in FIG. This solar cell module can be used, for example, for a space solar cell (for artificial satellite mounting).

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the solar cell module of one embodiment of this invention, Comprising: (a) is a top view of the solar cell module seen from the light-receiving surface side, (b) is the Ib-Ib line cross section in (a). FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic explaining one process of the manufacturing process of the solar cell module of one embodiment of this invention, (a) is a top view of a photovoltaic cell, (b) is sectional drawing of a photovoltaic cell. It is the schematic explaining the other process of the manufacturing process of the solar cell module of this invention, (a) is a top view of a solar cell string, (b) is sectional drawing of a solar cell string, (c) is 2 rows. It is a top view in the state where a solar cell string was formed. It is a schematic sectional drawing which shows the other process of the manufacturing process of the solar cell module of one embodiment of this invention. It is a schematic sectional drawing which shows the other process of the manufacturing process of the solar cell module of this invention. (A), (b) is a schematic sectional drawing which shows another process of the manufacturing process of the solar cell module of this invention. It is a figure which shows the temperature cycle test result of the solar cell module of this invention. When a transparent silicon resin thickness exceeds 75 micrometers vicinity, it is a schematic sectional drawing which shows the state where the wavy wrinkle entered the flexible transparent cover board. It is a schematic diagram of the conventional solar cell module, (a) is a top view of a photoelectric conversion apparatus, (b) is IXb-IXb sectional drawing of the said photoelectric conversion apparatus, (c) is IXc-IXc cross section of the said photoelectric conversion apparatus. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Board | substrate, 2 silicone resin, 3 transparent silicone resin, 4 flexible transparent cover board, 5 interconnector, 6 photovoltaic cell, 7 bus bar, 8 external connection part, 10 surface electrode, 11 semiconductor layer, 12 back surface electrode, 13 Release film.

Claims (7)

A solar cell array formed by connecting a solar cell string including a plurality of solar cells electrically connected by an interconnector to a bus bar;
A transparent silicon resin that covers the entire upper and lower surfaces of the solar cell array and is laminated so as to enclose the solar cell array, and laminated,
A solar cell module comprising: a flexible transparent cover plate formed immediately above the transparent silicon resin. The solar cell module according to claim 1, wherein the transparent silicon resin is disposed on a silicon resin formed immediately above the substrate. The solar cell module according to claim 1 or 2, wherein the thickness of the flexible transparent cover plate is 100 µm or less, and the thickness of the single crystal semiconductor layer constituting the solar cell is 50 µm or less. The solar cell module according to any one of claims 1 to 3, wherein the silicon resin and the transparent silicon resin have a viscosity at room temperature of 2,000 mPa · s to 100,000 mPa · s. The film thickness of the said transparent silicon resin is more than the sum of the thickness of the single-crystal semiconductor layer of the said photovoltaic cell, and the thickness of an interconnector, and is 75 micrometers or less, In any one of Claims 1-4. Solar cell module. Arranging a plurality of solar cells in series;
A step of forming a solar cell string by electrically connecting electrodes of adjacent solar cells among the plurality of solar cells by an interconnector;
Connecting a plurality of the formed solar cell strings to a bus bar to form a solar cell array;
Installing the solar cell array on a transparent silicon resin, and stacking another transparent silicon resin on the solar cell array;
A step of laminating the solar cell array, which is installed on the transparent silicon resin and overlaid with the transparent silicon resin from above, in a vacuum,
And a step of heating and curing the transparent silicon resin. The sun according to claim 6, further comprising a step of removing bubbles contained in the laminated solar cell module before the step of heating and curing the transparent silicon resin after the step of applying the laminate. Manufacturing method of battery module.

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