JP2010073720A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module which can be used stably for a long period even when thin type solar cells are used. <P>SOLUTION: The solar cell module having solar cells sandwiched using sealing materials between a light-incident-side transparent protective member and a back-side protective member is characterized in that a resin material A as a sealing material between the solar cell and back-side protective material has a smaller coefficient of linear expansion than a resin material B as a sealing material between the solar cell and light-incident-side protective member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solar cell module, and more particularly to a solar cell module with improved reliability.

  In recent years, solar cells that directly convert sunlight into electric energy have attracted attention and are being developed from the viewpoint of effective use of resources and prevention of environmental pollution.

  In general, a solar cell module is configured to sandwich a solar cell that generates power by receiving sunlight between a front surface and a back surface protection member using a sealing material such as ethylene-vinyl acetate (EVA) or silicone. It has a structure. In these solar cell modules, since an electromotive force is insufficient in one cell, it is rarely configured from a single cell, and usually a plurality of solar cells are connected in series or series-parallel. That is, as shown in FIG. 1, the electrodes of the solar cells are connected using a conductive material, and these solar cells and the conductive material are made of glass, resin plate, resin film, metal using a sealing material. It is sandwiched between protective members made of, for example.

  On the other hand, with the widespread use of solar cells, there is an increasing supply of silicon wafers used for solar cells and demands for cost reduction. Recently, studies have been conducted to make solar cells thinner. However, thin-layer solar cells are prone to warping and cracking due to heating, and when used in the same material and module configuration as before, it has been found that a new problem arises that durability is poor due to long-term use. I came. In particular, a solar cell module that is thinner than a conventional solar cell module manufactured by using a thin-layer solar cell has a large temperature rise of the sealing material and the back surface protection member on the back surface side of the solar cell due to heating by sunlight incident upon use, In general, a sealing material made of a resin material or a back surface protection member is thermally expanded, and a phenomenon occurs in which the solar battery cell is warped with the back surface side convex. In long-term use, there is a problem that such a thermal contraction of the solar battery cell repeatedly causes wiring defects such as cracking of the solar battery cell and peeling of the back electrode.

  On the other hand, as a technique for preventing the warpage of the solar battery cell, a method using a sealing material having different adhesive forces on the front surface side and the back surface side of the solar battery cell has been proposed (for example, see Patent Document 1). Since the difference in adhesive strength becomes smaller with time, it is difficult to maintain the effect over a long period of time. Furthermore, this method cannot solve the problem that the back surface side of the solar battery cell warps convexly.

  There has been proposed a method for solving a wiring defect due to thermal expansion and contraction of the base material by making the structure in which the sealing material layer and the plate-like base material are movably stacked (see, for example, Patent Document 2). This method cannot suppress the warpage of the solar battery cell itself.

On the other hand, although there has been a proposal for a method for containing inorganic fine particles in a sealing material layer, there has been no method using a resin material containing inorganic fine particles for the purpose of improving the physical properties of solar cells as in the present invention. It was. Inorganic fine particles are dispersed in the encapsulant layer as an acid acceptor (see, for example, Patent Document 3), and this is used as an encapsulant on the light receiving surface side, and the back surface of the solar cell as in the present invention. It is not effective on the side. In addition, although a method using inorganic fine particles as a light scattering material has been shown (for example, see Patent Document 4), the inorganic fine particles described here are inorganic fine particles having a large particle size for the purpose of scattering light. In such a configuration, the effect of suppressing the warpage of the solar cell as in the present invention is not obtained.
JP 2007-294869 A JP 2005-101032 A JP 2008-118073 A JP 2000-183381 A

  As described above, although it is required to make the solar cell thinner, when the thin-layer solar cell is used in the same module configuration as the conventional one, the warpage of the solar cell due to heating becomes larger than the conventional one. Therefore, a new problem has arisen that the stability of the solar cell module is lowered. Therefore, the objective of this invention is providing the solar cell module which can be used stably for a long period of time, even if it uses a thin photovoltaic cell.

  The above object of the present invention can be achieved by the following configuration.

  1. In a solar cell module in which a solar battery cell is sandwiched between a light incident side transparent protective member and a back surface side protective member using a sealing material, a sealing material between the solar cell and the back surface side protective member. A solar battery module, wherein a linear expansion coefficient of a certain resin material A is smaller than a linear expansion coefficient of a resin material B which is a sealing material between the solar battery cell and the light incident side transparent protective member.

  2. 2. The solar cell module according to 1 above, wherein the linear expansion coefficient of the resin material A is 1/2 to 1/50 of the linear expansion coefficient of the resin material B.

  3. 3. The solar cell module according to 1 or 2, wherein the resin material A is a resin material in which inorganic fine particles are dispersed.

  ADVANTAGE OF THE INVENTION According to this invention, the cost reduction by use of a thin layer photovoltaic cell can be achieved, and also the solar cell module which can be used stably for a long period of time with respect to the heating / cooling at the time of use can be provided.

  The present invention will be described in more detail.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a part of a cross section of a general solar battery module, in which adjacent solar battery cells 1 are connected by wiring 3.

  The solar cells thus connected are sandwiched between the light incident side transparent protective member 41 and the back side protective member 42 via the sealing material layer 2.

  In this invention, while making this photovoltaic cell 1 thinner than before, the back surface side sealing which is a low linear expansion resin material between the back surface of the photovoltaic cell 1 and the back surface side protection member 42 among the sealing material layers 2 is carried out. The solar cell module shown in FIG. 2 in which the stopper layer 22 is enclosed can be preferably used. Furthermore, as shown in FIG. 3, in order to improve the adhesiveness between the back surface side sealing material layer 22 and the back surface side protection member 42, which are the low linear expansion resin material, an adhesive layer 23 may be inserted between them. it can.

  The solar cell 1 used in the present invention has a semiconductor junction such as a PN junction or a PIN junction inside, a silicon semiconductor material such as single crystal silicon, polycrystalline silicon, or amorphous silicon, or a compound semiconductor such as GaAs or CuInSe. General solar cell materials such as organic materials such as materials and dye-sensitized systems can be used, but in the solar cell module configuration of the present invention, crystalline materials such as single crystal silicon, polycrystalline silicon, GaAs, and CuInSe The solar cell using is preferably used.

  The thickness of the solar battery cell of the present invention may be about 200 to 300 μm, which is conventionally used for crystalline silicon, but a thin solar battery cell of 150 μm or less is preferable because the high effect of the present invention can be obtained. In particular, a solar cell having a thickness of 30 to 100 μm using a thin silicon wafer is preferable.

  The solar cell module of the present invention includes a front side sealing material layer 21 that is a high linear expansion resin material (B) and a back side sealing material layer 22 that is a low linear expansion resin material (A) in a sealing layer. It is characterized by. Examples of high linear expansion resin materials include ethylene-vinyl acetate (EVA) and polyvinyl butyral (PVB), silicone resins, urethane resins, acrylic resins, fluorine resins, ionomer resins, ethylene- Resin materials having a linear expansion coefficient of 100 to 500 ppm / ° C., such as acrylic acid copolymer, ethylene-methacrylic acid copolymer, polyethylene resin, polypropylene resin, acid-modified polyolefin resin, and epoxy resin, are preferable, and particularly transparent. EVA having high lightness and adhesiveness is preferable.

  The low linear expansion resin material may be any resin material having a smaller linear expansion coefficient than the above-mentioned high linear expansion resin material, but the linear expansion coefficient is ½ that of the high linear expansion resin material in the solar cell module. It is preferable to be used in a combination of ˜1 / 50. The linear expansion coefficient of the low linear expansion resin material is preferably 5 to 50 ppm / ° C, more preferably 5 to 30 ppm / ° C, although it depends on the types of the solar battery cell and the back surface side protection member.

  Examples of the resin having a linear expansion coefficient of 50 ppm / ° C. or less that can be preferably used as the low linear expansion resin material include polycarbonate resins, polyimide resins, polyphenylene ether resins, and the like. These resins can be used alone or in combination. it can. Furthermore, in order to enclose these resin between a photovoltaic cell and a back surface side protection member, it is preferable to use as a sheet-like film of thickness 50-1000 micrometers, for example.

  The solar cell module of the present invention preferably includes a front side sealing material layer 21 that is a high linear expansion resin material and a back side sealing material layer 22 that is a resin material in which inorganic fine particles are dispersed in the sealing layer. . Here, as the resin material of the base material in which the inorganic fine particles are dispersed, any of generally known resin materials may be used. However, in the present invention, the resin material generally used as the transparent sealing material described above. Can be preferably used.

  Examples of the inorganic fine particles include carbon black, carbon fiber, clay compounds such as talc generally used as a reinforcing material for resins, glass beads, carbonate fine particles such as calcium carbonate, and oxide fine particles such as alumina. In the present invention, carbonate fine particles and oxide fine particles are preferably used because of low linear expansion and reduction of heating due to the absorption of sunlight.

  Specifically, for example, titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, yttrium oxide, lanthanum oxide, cerium oxide, oxide Indium, tin oxide, lead oxide, lithium niobate, potassium niobate, lithium tantalate, etc. that are composed of these oxides, phosphates, sulfates, etc. formed in combination with these oxides Can be mentioned.

  In addition, fine particles having a semiconductor crystal composition can be preferably used as the inorganic fine particles of the present invention. There is no restriction | limiting in particular in this semiconductor crystal composition, Although fluorescent substance etc. can be used, What does not prevent the light absorption of a photovoltaic cell is preferable. For example, a material that absorbs ultraviolet light or the like and emits light in a wavelength region where the absorption intensity of the solar battery cell is high is desirable.

  One kind of these inorganic fine particles may be contained in the resin, or a plurality of kinds of inorganic fine particles may be used in combination.

  The content of the inorganic fine particles is not particularly limited as long as the effect of the present invention can be exhibited, and can be arbitrarily determined depending on the kind of the resin and the inorganic fine particles. However, if the content of the inorganic fine particles is high, the film formability deteriorates. And it is not preferable because it becomes difficult to use as a film. Therefore, the content of the inorganic fine particles is preferably 30% or less with respect to the mass of the resin, more preferably 0.1% by mass or more and 20% or less, and further preferably 0.1% by mass or more and 10% or less. .

  The average particle diameter of the inorganic fine particles is preferably 1 nm or more and 1 μm or less, and more preferably 1 nm or more and 100 nm or less. If it is less than 1 nm, it is difficult to disperse the particles, so that the desired performance may not be obtained. If it exceeds 1 μm, a large amount of inorganic fine particles is required to obtain the desired effect, and as a result, it is used as a film. Becomes difficult. The average particle diameter here refers to the diameter when converted to a sphere having the same volume as the particle.

  The shape of the inorganic fine particles used in the present invention is not particularly limited, and acicular or spherical fine particles are preferably used. Further, the particle size distribution is not particularly limited, but in order to achieve the effect of the present invention more efficiently, a particle having a relatively narrow distribution is preferably used rather than a particle having a wide distribution. Used.

  The resin material in which the inorganic fine particles are dispersed preferably has a low linear expansion coefficient, and the inorganic fine particles are preferably dispersed in the resin material so as to have a linear expansion coefficient of 5 to 50 ppm / ° C. Moreover, since it encloses between a photovoltaic cell and a back surface side protection member, it is preferable to obtain as a sheet-like film of thickness 50-1000 micrometers, for example.

  The low linear expansion resin material is disposed so as to contact the back surface of the solar battery cell 1 provided with the back electrode and the wiring material as shown in FIG. It is characterized by that. At the time of manufacturing the solar cell module, these members are sealed by a vacuum laminating apparatus or the like, so that the resin material and the solar battery cell are bonded, and the resin material and the back surface protective material are bonded, for example, A silane coupling agent can be blended in the resin material to further improve the adhesion. Further, in order to improve the adhesion between the resin material and the back surface protective material, an adhesive layer as shown in FIG. 3 may be newly provided. As the adhesive layer, a resin material such as EVA used for a sealing material on the upper surface of the solar battery cell is preferably used.

  Note that a solar battery module in which electrodes are formed only on the back surface side of the solar battery cells and the back surfaces of the solar battery cells are connected by wiring as shown in FIG. 4 is also one of the preferred embodiments of the present invention.

The front electrode 11, the back electrode 12, and the wiring 3 are formed of a conductive material such as silver, aluminum, copper, nickel, tin, gold, or an alloy thereof. Note that the electrode may have a single layer structure containing a conductive material or a multilayer structure. In addition to the layer containing these conductive materials, SnO 2, _ITO, IWO, it may have a layer including a translucent conductive oxide such as ZnO.

  The light incident side transparent protective member 41 is usually a glass substrate such as silicate glass. As for the thickness of a glass substrate, 0.1-10 mm is common, and 0.3-5 mm is preferable. The glass substrate may generally be chemically or thermally strengthened. A resin material can also be used to reduce the weight of the solar cell module.

  The resin material used as the light incident side transparent protective member is not particularly limited as long as the light receiving surface side of the solar cell is translucent. For example, polycarbonate, acrylic resin, polyethylene terephthalate, polybutylene terephthalate, Polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinylidene chloride, polyphenylene sulfide, polyamide, polyurethane, polymethacrylate, polyacrylonitrile, ABS, phenol resin, melamine resin, formaldehyde resin, urea resin, unsaturated polyester resin, It may be composed of an epoxy resin, natural rubber or a derivative thereof, or may be composed of two or more kinds of the above resins, or may be composed of two or more kinds of resin plates bonded together. In addition, an inorganic filler such as aluminum hydroxide or calcium hydroxide, a flame retardant, or the like may be sewn to provide nonflammability or flame retardancy. Further, it may be foamed by adding a foaming agent or the like, and may further be added with a plasticizer, a stabilizer, a foaming aid, an ultraviolet absorber, a pigment, or the like, and a metal foil is bonded thereto. It may be a thing.

  The back side protective member 42 can be made of the same material as the light incident side transparent protective member 41. Further, in order to reduce the mass of the entire module, a relatively soft film-like PET (polyethylene terephthalate) film is used. Or a resin film such as a fluororesin film, a resin film on which a metal oxide vapor deposition film such as silica or alumina is formed, a metal film such as an aluminum foil, or a laminated film thereof. .

  In this invention, the solar cell module by which the low linear expansion coefficient film was installed in the back surface of the photovoltaic cell by said structure is obtained. As a result, the low linear expansion coefficient film suppresses the warpage of the solar battery cell due to the irradiation of sunlight. Moreover, the surprising effect that the adhesiveness of the electrode and wiring material which were installed in the back surface of a photovoltaic cell improves by installing the film containing an inorganic fine particle in the back surface of a photovoltaic cell is acquired. Therefore, even when the solar battery cell is warped by heating, it is possible to suppress a decrease in efficiency due to peeling of the electrode and the wiring material. Therefore, by using a low linear expansion coefficient film in which inorganic fine particles are dispersed on the back surface of the solar battery cell, even when a thin solar battery cell having a thickness of 150 μm or less is used, a solar battery module having higher durability than conventional ones is produced. It becomes possible.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the aspect of this invention is not limited to this.

<Preparation of sealing film>
Using an EVA resin composition having the following composition, an EVA film and a sealing film in which inorganic fine particles were dispersed in EVA were prepared.

[EVA resin composition blended (values indicate parts by mass)]
EVA resin (vinyl acetate content 26% by mass) 100
Cross-linking agent (1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane) 2.0
Crosslinking aid (triallyl isocyanurate) 3.0
Inorganic fine particles Formulations shown in Table 1 in proportions shown in Table 1.

  After the inorganic fine particle powder is gradually added to the mixture of the EVA resin, the crosslinking agent and the crosslinking aid, the mixture is kneaded at 80 ° C. with a biaxial kneader, and then the resulting resin composition is calendered at 100 ° C. and allowed to cool. Thereafter, sealing films EVA-2 to EVA-6 were obtained in which inorganic fine particles were dispersed in EVA having a thickness of 600 μm. In these materials, an EVA film having a thickness of 600 μm that does not contain inorganic fine particles was also produced, and this was designated as EVA-1.

<Production of solar cell module>
As shown in FIG. 2 or FIG. 3, the solar cell 1 is interposed between a light incident side transparent protective member 41 made of a glass plate (thickness 3 mm) and a back side protective member 42 made of a polycarbonate sheet (thickness 1 mm). A solar cell module was manufactured by sealing with four connected in series. As the solar cell, three types having a thickness of 50 μm, 150 μm, and 250 μm using a single crystal silicon wafer and having aluminum electrodes on the front and back surfaces were used. Further, as the resin material (sealing material B) of the front surface side sealing material layer 21 and the resin material (sealing material A) of the back surface side sealing material layer 22, the above-mentioned EVA-1 to EVA-6 having a film thickness of 600 μm are used. And sheets of 800 μm thick Zylon G701H and G703H, which are modified polyphenylene ether resins manufactured by Asahi Kasei Chemicals Corporation. Sealing was performed by thermocompression bonding with a vacuum laminator at a temperature of 150 ° C. under vacuum.

<Evaluation of solar cell module>
The solar cell module produced above was irradiated with pseudo-sunlight at 25 ° C. and an irradiation intensity of 1000 mW / cm ² by a solar simulator whose spectrum was adjusted to AM 1.5, and the open voltage [V] of the solar cell and 1 cm ^2. The nominal maximum output operating current [A] and the nominal maximum output operating voltage [V] are measured, and the nominal maximum output [W] (JIS C8911 1998) is obtained from these products, and this is used as the reference output of each module. .

  Next, the solar cell module was installed on a hot plate, and the solar cell module was subjected to a heat cycle test, with 6 hours as one cycle after the hot plate was operated at 100 ° C. for 3 hours and then stopped for 3 hours. And the nominal maximum output [W] in the time of 200 cycles, 400 cycles, and 600 cycles was calculated | required, and the output ratio [%] which remove | divided this by the above-mentioned reference | standard output was calculated | required. The results are shown in Table 2.

  From Table 2, it can be seen that the solar cell module of the present invention has a small output drop in the heat cycle test, and a stable output can be obtained even after long-term use.

It is the schematic of the cross section of a common solar cell module. It is the schematic of the cross section which shows the aspect of the solar cell module of this invention. It is the schematic of the cross section which shows another aspect of the solar cell module of this invention. It is the schematic of the cross section which shows another aspect of the solar cell module of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Sealing material layer 3 Wiring 11 Front surface electrode 12 Back surface electrode 21 Front surface side sealing material layer 22 Back surface side sealing material layer 23 Adhesive layer 41 Light incident side transparent protective member 42 Back surface side protective member

Claims (3)

In a solar cell module in which a solar battery cell is sandwiched between a light incident side transparent protective member and a back surface side protective member using a sealing material, a sealing material between the solar cell and the back surface side protective member. A solar battery module, wherein a linear expansion coefficient of a certain resin material A is smaller than a linear expansion coefficient of a resin material B which is a sealing material between the solar battery cell and the light incident side transparent protective member. The solar cell module according to claim 1, wherein a linear expansion coefficient of the resin material A is 1/2 to 1/50 of a linear expansion coefficient of the resin material B. The solar cell module according to claim 1 or 2, wherein the resin material A is a resin material in which inorganic fine particles are dispersed.

Images