WO2013031954A1 - Solar cell module and photovoltaic generation system - Google Patents

Abstract

The purpose of the present invention is to provide a highly reliable solar cell module that exhibits an increased durability to moisture permeation and an increased solar cell matrix fixing strength in the layers of the solar cell module. This solar cell module (M1) comprises the following, which are sequentially layered: a translucent substrate (1) on which light is incident; a first resin layer (2); a solar cell element group (3') comprising at least one solar cell element (3); a second resin layer (4) comprising an unesterified thermoplastic resin; and a protective sheet (5).

Description

Solar cell module and solar power generation system

The present invention relates to a solar cell module and a solar power generation system including the same.

Generally, a solar cell module constituting a solar power generation system is formed by laminating a plurality of materials. The laminated structure is, for example, a glass substrate, a resin layer, a photoelectric conversion unit, a resin layer, and a back surface protective film in this order from the light receiving surface side, and the structure of such a solar cell module is called a super straight structure.

As the resin layer constituting the solar cell module, an ethylene-vinyl acetate copolymer to which a cross-linking agent is added (hereinafter, ethylene-vinyl acetate copolymer is abbreviated as EVA) is used. In addition, a photoelectric conversion unit is used in which a plurality of solar cell elements using a silicon substrate having a pn junction are electrically connected to each other by an interconnect such as a copper foil.

In such a solar cell module, when moisture permeates from the back surface protective film, the resin layer (EVA) is hydrolyzed due to secular change or the like. Since EVA generates acetic acid by hydrolysis, this acetic acid may corrode the electrical connection portion and connection wiring of the photoelectric conversion portion. Moreover, the adhesive force of the interface of a resin layer and a photoelectric conversion part, or the interface of a resin layer and a back surface protective film may fall by a cross-linking agent or an acetic acid by a secular change.

Therefore, a solar cell module using a thermoplastic resin that does not generate acetic acid even when the resin layer is hydrolyzed and does not contain a crosslinking agent has been proposed (see, for example, JP-A-2007-103738).

However, when the resin layer is changed to the thermoplastic resin as described above, if a sudden temperature change is repeatedly applied, the photoelectric conversion unit repeats thermal expansion and contraction, and the photoelectric conversion unit expands in the resin layer. There is a possibility that the interconnector in the photoelectric conversion unit may move away from the output extraction electrode of the solar cell element. In addition, the output power and FF (fill factor) of the solar cell module may be reduced accordingly.

Accordingly, one of the objects of the present invention is to increase the fixing strength of the solar cell matrix in the stacking of the solar cell modules while increasing the durability against moisture permeability, and to provide a highly reliable solar cell module and solar power generation system. Is to provide.

A solar cell module according to an embodiment of the present invention includes a translucent substrate on which light is incident, a first resin layer, a solar cell element group including one or more solar cell elements, and a non-ester thermoplastic resin. The second resin layer made of and a protective sheet are sequentially stacked.

In addition, a solar power generation system according to an embodiment of the present invention includes the above solar cell module.

According to the solar cell module and the photovoltaic power generation system configured as described above, as the second resin layer disposed between the photoelectric conversion unit and the protective sheet, a thermoplastic resin that does not generate acetic acid by hydrolysis is disposed. Corrosion of the electrodes constituting the solar cell element and the interconnector connecting the solar cell elements can be suppressed.

In particular, since the second resin layer is substantially free of a cross-linking agent, when used for a long time, the cross-linking agent and the acetic acid cause the space between the protective sheet and the second resin layer, and the solar cell element. A decrease in the adhesive force between the group and the second resin layer can be suppressed.

As described above, according to the solar cell module and the solar power generation system configured as described above, a highly reliable solar cell having high strength against a temperature change while obtaining an effect of reducing acetic acid generated with hydrolysis. Modules and photovoltaic systems can be provided.

FIG. 1 is a drawing schematically showing a solar cell module according to an embodiment of the present invention, FIG. 1 (a) is a plan view seen from the light receiving surface side, and FIG. 1 (b) is FIG. 2 is a cross-sectional view taken along line AA ′ in FIG. FIG. 2 is a drawing schematically showing a solar cell module according to another embodiment of the present invention, FIG. 2 (a) is a plan view seen from the light receiving surface side, and FIG. 2 (b) is a plan view of FIG. It is sectional drawing cut | disconnected by CC 'line | wire in a). FIG. 3 is a block diagram illustrating an embodiment of a photovoltaic power generation system according to an embodiment of the present invention. FIGS. 4A and 4B are plan views (partially photographs) showing a state after the temperature cycle test of the solar cell module according to the comparative example, respectively. Fig.5 (a), (b) is a top view (partial photograph) which shows the mode after the temperature cycle test of the solar cell module which concerns on an Example, respectively.

Hereinafter, embodiments of a solar cell module and a photovoltaic power generation system according to the present invention will be described in detail with reference to the drawings.

<< First Embodiment of Solar Cell Module >>
<Basic configuration of solar cell module>
As shown in FIGS. 1A and 1B, a solar cell module M1 according to this embodiment includes a translucent substrate 1, a translucent first resin layer 2, and a plurality of solar cell elements 3. The electrically connected solar cell element group (solar cell matrix) 3 ′, the second resin layer 4, and the back surface protective film 5 that is a protective sheet are laminated in this order. The plurality of solar cell elements 3 are electrically connected by the interconnector 6 and the connection wiring 7.

Here, in particular, the second resin layer 4 is preferably made of a polyethylene resin. In particular, the first resin layer 2 is preferably made of a non-ester resin, and particularly preferably a polyethylene resin. Moreover, in the said solar cell module M1, it is good that the 1st resin layer 2 has a crosslinking agent, and the 2nd resin layer 4 does not have a crosslinking agent substantially.

Note that the solar cell module M1 may include a terminal box (not shown) for taking out the electric power generated by the solar cell element 3 outside the back surface protective film 5.

Next, each component constituting the solar cell module M1 will be described.

<Translucent substrate>
The translucent substrate 1 has a light receiving surface 1a on which light is mainly incident and a back surface 1b to which the first resin layer 2 is bonded. Such a translucent substrate 1 is, for example, blue plate glass (soda lime glass) or white plate glass obtained by removing iron from blue plate glass, glass such as hard glass, synthetic resin such as transparent polycarbonate resin or transparent acrylic resin, Or what is hard and has translucency is used. Moreover, the shape of the translucent board | substrate 1 is not restricted to the flat form which has a plane, The shape which has a curved surface according to a use may be sufficient. As long as the thickness of the translucent board | substrate 1 is a flat thing, the thing of about 3 mm can be used in the case of glass, and the thing of about 5 mm can be used in the case of a synthetic resin.

<First resin layer>
The first resin layer 2 has a function of sealing the solar cell element group 3 ′ in cooperation with the second resin layer 4. Furthermore, the 1st resin layer 2 has a function which adhere | attaches the translucent board | substrate 1 and solar cell element group 3 '. The first resin layer 2 is obtained by curing EVA (ethylene-vinyl acetate copolymer) to which a crosslinking agent is added, and the main component EVA is 80 parts by mass with respect to 100 parts by mass of the first resin layer. A sheet-like material having a thickness of about 0.4 to 1 mm and having a mass part or more is used.

As the crosslinking agent, an organic peroxide can be used. For example, 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane or the like can be used. The organic peroxide content may be added so as to be 0.5 to 5 parts by mass with respect to 100 parts by mass of the first resin layer. Moreover, you may add a crosslinking adjuvant or a ultraviolet absorber as needed. The first resin layer 2 and the second resin layer 4 are fused with each other by applying heat and pressure under reduced pressure by a laminating apparatus, and are cross-linked to be integrated with the solar cell element group 3 ′ and other members.

<Solar cell element group>
The solar cell element group 3 ′ is a photoelectric conversion unit and has a function of converting incident sunlight into electricity. The solar cell element group 3 ′ in the present embodiment is a solar cell matrix in which a plurality of solar cell elements 3 are electrically connected.

The solar cell element 3 is made of, for example, single crystal silicon or polycrystalline silicon having a thickness of about 0.1 to 0.4 mm. A pn junction is formed inside the solar cell element 3, and electrodes are provided on the light receiving surface and the back surface, respectively. Further, an antireflection film may be provided on the light receiving surface side. The size of the solar cell element 3 is about 70 to 160 mm square and about 200 μm in thickness for polycrystalline silicon. Such solar cell elements 3 constitute a solar cell matrix by being electrically connected in series or in parallel by the interconnector 6 and the connection wiring 7.

For example, in the case of a solar cell module of about 190 W, the solar cell element group 3 ′ is formed by electrically connecting the solar cell elements 3 arranged in 8 rows and 6 columns by the interconnector 6 and the connection wiring 7. The plane size of the battery element group 3 ′ is about 1300 mm × 1000 mm.

<Second resin layer>
The second resin layer 4 only needs to contain a non-ester thermoplastic resin as a main component. That is, when the 2nd resin layer 4 is 100 mass parts, 80 mass parts or more of non-ester type thermoplastic resins are included. The non-ester thermoplastic resin is, for example, a polyethylene resin that does not have a crosslinking agent. For example, the non-ester thermoplastic resin is a thermoplastic resin obtained by polymerizing a polyethylene compound containing an ethylene-α-olefin copolymer as a main component. Such a second resin layer 4 is in the form of a sheet having a thickness of about 0.4 to 1 mm.

The second resin layer 4 is fused and integrated with the solar cell matrix 3 ′ and other members by applying heat and pressure under reduced pressure using a laminating apparatus. The second resin layer 4 may be any material as long as it does not produce a corrosion product such as acetic acid by hydrolysis and has a flexibility to alleviate the impact applied to the solar cell matrix 3 ′. In addition, a cyclic olefin compound, a vinyl aromatic compound, a polyene compound, a propylene compound, a butene compound, a hexene compound, or an octene compound may be used, or a polymer obtained by polymerizing one or more of them may be used. The propylene compound is propylene polymerized with an ethylene-α-olefin copolymer. Similarly, the butene compound is butene polymerized with an ethylene-α-olefin copolymer, and the hexene compound is an ethylene-α-olefin. 1-hexene polymerized with the copolymer, and the octene compound is 1-octene polymerized with the ethylene-α-olefin copolymer.

Such a second resin layer 4 differs from the first resin layer 2 in that it does not contain ester-based vinyl acetate, so that acetic acid, which is a corrosive product, is generated with hydrolysis due to moisture absorption. There is no.

In addition, if the melting point of the second resin layer 4 is too high, the heating temperature at the time of manufacturing the solar cell module becomes too high and the soldered portion of the solar cell matrix 3 ′ may come off. Preferably there is.

<Protective sheet>
The back surface protective film 5 used as a protective sheet has a function of reducing moisture from entering the solar cell element 3, the first resin layer 2, and the second resin layer 4. Examples of such a back surface protective film 5 include a polyethylene terephthalate (PET) sheet, a polyethylene naphthalate (PEN) sheet, a polyvinyl fluoride (PVF) sheet, a laminate thereof, and a weather-resistant fluorine sandwiching an aluminum foil. A resin sheet or a polyethylene terephthalate (PET) sheet on which alumina or silica is deposited is used.

<Interconnector and connection wiring>
The interconnector 6 and the connection wiring 7 have a function of electrically connecting the solar cell elements 3 to each other. The interconnector 6 and the connection wiring 7 are not particularly limited in shape and material, but for example, a copper foil having a thickness of about 0.1 mm and a width of about 1 mm to 6 mm coated with solder is used for a predetermined amount. It is good to cut | disconnect to length and to solder on the electrode of the solar cell element 3, etc. The thermal expansion coefficient of copper is 16.5 × 10 ⁻⁶ / ° C., and the thermal expansion length per 1300 mm when the temperature change is 80 ° C. is 1.7 mm, for example.

<Effect>
Next, the effect of the solar cell module according to this embodiment will be described. Since the solar cell module M1 has a super straight structure, the back side is protected with a resin film such as a PET sheet. For this reason, the moisture permeability from the back surface side where the resin film is arrange | positioned as the back surface protective film 5 is larger than the light-receiving surface side where glass etc. were used as the translucent board | substrate 2. FIG.

However, since the second resin layer 4 is a thermoplastic resin that does not generate acetic acid by hydrolysis as described above, even if the second resin layer 4 absorbs moisture through the back surface protective film 5. Corrosion products such as acetic acid are not generated.

Moreover, since the 2nd resin layer 4 does not produce acetic acid and does not contain a crosslinking agent, acetic acid or the crosslinking agent is a factor of acetic acid or the crosslinking agent due to long-term use. It is possible to suppress a decrease in the adhesive force between the second filler 4 and the back surface protective film 5.

Moreover, the water reaching the first resin layer 2 can be reduced, and acetic acid generated from the first resin layer 2 can be reduced.

Further, the thermoplastic resin used for the second resin layer 4 is subjected to strong binding force at the crosslinking point in the process of returning to room temperature after the crosslinking is completed, like the thermosetting resin when the crosslinking agent is added. There is an advantage that water absorption is less likely to occur than when the molecular motion is fixed in a large free volume state.

In addition, since the first resin layer 2 is EVA to which a cross-linking agent is added, the first resin layer 2 may be cross-linked into a rubber-like elastic body by performing heating and pressurization in the manufacturing process. A rubber-like elastic body obeys Hooke's law over a wide stress range, and has the property of returning to its original shape when an external force is removed.

From this, even when the solar cell element group 3 'moves through the resin layer due to thermal expansion / contraction due to temperature change in the surrounding environment, it returns to the original position as it returns to room temperature. Can do.

The cross-linking of the first resin layer 2 will be described in more detail. By adding an organic peroxide cross-linking agent to EVA and raising the temperature to be higher than the decomposition temperature of the organic peroxide, the chain polymers are chemically bonded to each other. It is a chemical cross-link having a network structure. Due to the chemical crosslinking, the first resin layer 2 is unlikely to be irreversibly deformed even at a high temperature. In addition, since the first resin layer 2 is bonded to the hard translucent substrate 2, the translucent substrate 2 is unlikely to expand and contract by an external force unlike the back surface protective film 5. The position of the battery element group 3 ′ is difficult to shift and can return to the original position stably.

Moreover, since EVA has higher translucency than polyethylene-based resin, the power generation efficiency of the solar cell element group 3 ′ can be increased by using EVA for the first resin layer 2.

This makes it possible to obtain a highly reliable solar cell module that does not deform with respect to temperature changes while obtaining the effect of introducing a thermoplastic resin that does not generate acetic acid.

<< Second Embodiment of Solar Cell Module >>
Next, 2nd Embodiment which is other embodiment of a solar cell module is described.

A solar cell module using a polyethylene resin having a crosslinking agent in the first resin layer 2 may be used. Since the other configuration is the same as that of the first embodiment, description thereof is omitted.

According to such a solar cell module, when the usage environment of the solar cell module is severe and the side surface of the solar cell module is in contact with outside air or rainwater containing moisture, moisture is permeable from the first resin layer 2 side. However, since the 1st resin layer 2 does not produce corrosion products, such as acetic acid, the fall of power generation efficiency can be controlled.

Further, by using polyethylene having a crosslinking agent for the first resin layer 2, the effect of suppressing the positional deviation of the solar cell element group 3 'can be obtained as in the first embodiment.

This can improve the reliability of the solar cell module.

<< Third Embodiment of Solar Cell Module >>
Next, 3rd Embodiment which is further another embodiment of a solar cell module is described.

As shown in FIG. 2, the solar cell module M <b> 2 is a solar cell element group 3 ′ in which a back contact solar cell element is used as the solar cell element 3 and the interconnector 6 is disposed on the side facing the second resin layer 4. Is used.

According to this solar cell module M2, even if the use environment of the solar cell module M2 is severe and moisture passes to the first resin layer 2 and acetic acid is generated from the first resin layer 2, the solar cell element Since the electrical connection part of 3 and the interconnector and 6 is arrange | positioned so that the 2nd resin layer 4 may be contact | connected, the influence of the corrosion of the electroconductive part produced by an acetic acid can be reduced. Thereby, the reliability of a solar cell module can be improved.

<< Solar power generation system >>
For example, as shown in FIG. 3, the photovoltaic power generation system according to one embodiment of the present invention includes a solar cell module 40 in which a plurality of solar cell elements are electrically connected, and a solar cell module 40. And a power converter 45 to which DC power is input.

The power conversion device 45 is, for example, an input filter circuit 41 for DC smoothing, a power conversion circuit 42 for converting DC power into AC power, an output filter circuit 43 for AC smoothing, and power conversion control. The control circuit 44 is provided. In this way, the commercial power from the power conversion device 45 is output to the commercial power supply system 46. According to this solar power generation system 50, the solar cell module constituting the solar cell module that employs the solar cell modules according to the first to third embodiments described above provides excellent durability and reliability. A power generation system can be provided.

Note that the solar power generation system 50 may be provided with a solar cell array in which a plurality of solar cell modules are electrically connected instead of the solar cell module 40.

Next, an example embodying the first embodiment will be described. *

As shown in FIG. 1, the solar cell module M1 of this example includes a light-transmitting substrate 1 made of white glass and about 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane as EVA. A translucent first resin layer 2 added with 3 parts by mass, a solar cell element group 3 'in which a large number of solar cell elements 3 are electrically connected to each other by a copper foil interconnector, and an ethylene-α-olefin copolymer A second resin layer 4 that is a polyethylene-based thermoplastic resin obtained by polymerizing a combined polyethylene compound and a back surface protective film 5 made of polyethylene terephthalate were laminated in this order. Here, the solar cell element group 3 ′ is obtained by electrically connecting the solar cell elements 3 arranged in 8 rows and 6 columns by the interconnector 6 and the connection wiring 7, and the size on the plane is about 1300 mm × It was set to 1000 mm.

And in order to confirm the effect of a present Example, the temperature cycle test was done based on JIS C8917 (The environmental test method and durability test method of a crystalline solar cell module). This temperature cycle test is a test for the purpose of investigating the durability of a solar cell module by repeating a rapid temperature change. The temperature cycle conditions were 100 ° C. on the high temperature side, −40 ° C. on the low temperature side, and 250 cycles.

Also, a temperature cycle test was performed on the solar cell module of the comparative example under the same test conditions as described above. That is, the same material as that of the second resin layer 4 was disposed as the third resin layer above and below the solar cell element group 3 ', and the solar cell module M3 similar to that of the present example was tested.

As a result of these tests, the solar cell module M3 which is a comparative example has a position where the connection wiring 7 of the solar cell element group 3 ′ protrudes from the peripheral portion 1b of the translucent substrate 1 as shown in FIG. As shown in FIG. 4B, the interconnector 6 was bent and deformed such as being detached from the output extraction electrode of the solar cell element 3. Along with this, the maximum output operating power decreased by about 15%, and the FF decreased by about 15%.

This is considered due to the fact that the third resin layer is a thermoplastic resin that does not contain a crosslinking agent. That is, since the third resin layer does not cause a chemical cross-linking reaction, the molecular chain slips and fluidity tends to occur at a high temperature. For this reason, when a temperature cycle in which the high temperature side rises to near the melting point is applied, a distribution occurs in the force for returning the solar cell element group 3 ′ to the original position, and the slight position of the solar cell element group 3 ′ is generated. This is probably because the movement accumulated without returning to the original position when the temperature was returned to room temperature.

On the other hand, in the solar cell module M1 of the present embodiment, as shown in FIGS. 5A and 5B, the position shift of the solar cell element group 3 ′ and the interconnector from the output extraction electrode of the solar cell element 3 No deviation of 6 occurred. Moreover, the electrical characteristics of the solar cell module M1 did not deteriorate.

From the above test results, it was confirmed that the solar cell module M1 of this example had higher durability against temperature changes than the solar cell module M3 of the comparative example.

M1, M2: Solar cell module 1: Translucent substrate 1b: Peripheral part 2: First resin layer 3: Solar cell element 3 ′: Solar cell element group 4: Second resin layer 5: Back surface protective film 6: Interconnector 7: Connection wiring 11: Third resin layer 12: Fourth resin layer

Claims (8)

A translucent substrate on which light is incident, a first resin layer, a solar cell element group composed of one or more solar cell elements, a second resin layer composed of a non-ester thermoplastic resin, and a protective sheet Solar cell modules that are stacked one after another. The solar cell module according to claim 1, wherein the second resin layer is made of a polyethylene resin. The solar cell module according to claim 1 or 2, wherein the first resin layer is made of a non-ester resin. The solar cell module according to claim 3, wherein the first resin layer is made of a polyethylene resin. The solar cell module according to any one of claims 1 to 4, wherein the first resin layer has a crosslinking agent, and the second resin layer has substantially no crosslinking agent. The solar cell module according to claim 1, 2 or 5, wherein the first resin layer comprises an ethylene-vinyl acetate copolymer having a crosslinking agent. The solar cell module according to claim 6, wherein the plurality of solar cell elements are electrically connected by an interconnector disposed only on the second resin layer side. A solar power generation system comprising the solar cell module according to any one of claims 1 to 7.

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