JP2010034353A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module lowering a temperature and equalizing a temperature distribution when hot spots occur by a simple structure. <P>SOLUTION: The solar cell module includes: a translucent substrate; a solar cell matrix composed of solar cell strings formed by connecting a plurality of solar cell elements in a straight line shape with inner leads and lateral wiring provided so as to electrically series-connect a plurality of solar cell strings arranged in parallel, and sealed with a filling material; and bypass elements formed by being laminated by a back surface protecting material, arranged at a back surface side of the solar cell matrix, and electrically connected in parallel to the solar cell strings. The bypass elements are arranged so as to overlap with regions formed between the solar cell elements in a transparent plan view. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solar cell module.

  In recent years, the market of solar cell modules has been expanded from the viewpoint of environmental protection. As a result, solar cell modules are not limited to Japan and Europe, but are increasingly installed in areas near the equator where the temperature and solar radiation intensity are high, or in high-temperature environments such as boats and warehouses where temperatures rise easily. ing. Thus, a solar cell module that can withstand a high temperature environment is demanded.

  By the way, in the solar cell module, depending on the use environment, fallen leaves, dust, and the like may accumulate on the solar cell module and cause a shadow on the solar cell element. In such a case, the solar cell element generates a so-called hot spot phenomenon in which the amount of power generation decreases and the resistance increases and abnormal heat is generated. Solar cell elements (hot spot cells) that generate heat due to hot spots themselves are damaged at high temperatures, the filler around the hot spot cells foams and becomes cloudy, or the back surface protective material that overlaps the hot spot cells bulges. As a result, the solar cell module is damaged.

In order to prevent such damage, a bypass element is provided for the purpose of bypassing the current flowing through the solar cell string. However, the bypass element also generates heat due to the current flowing, and in some cases, the terminal box and the potting material filling the terminal box are thermally deformed, the connection between the bypass element and the solar cell element is peeled off, and the bypass element is damaged. give. For the purpose of reducing overheating of the bypass element, Patent Document 1 discloses that a heat dissipation relay terminal is provided in a terminal box.
Japanese Patent Laid-Open No. 2004-247708

  However, Patent Document 1 suppresses overheating of the bypass element itself, and does not suppress overheating of the solar cell element caused by the hot spot phenomenon. Accordingly, an object of the present invention is to provide a solar cell module with a simple structure, which suppresses a temperature rise caused by a hot spot phenomenon, leveles a temperature distribution, and improves reliability.

  The present inventors have found that when a hot spot occurs, heat is generated in the hot spot cell, and the bypass element also generates heat, and by specifying these positional relationships, damage to the solar cell module can be suppressed. As a result, the present invention has been completed.

  In the present invention, a translucent substrate, a solar cell string formed by linearly connecting a plurality of solar cell elements by inner leads, and a plurality of the solar cell strings arranged in parallel are electrically connected in series. A solar cell matrix sealed with a filler, which is composed of provided horizontal wirings, and a back surface protective material are laminated, arranged on the back side of the solar cell matrix, and electrically connected to the solar cell string. In the solar cell module composed of bypass elements connected in parallel, the bypass elements are arranged so as to overlap regions formed between the solar cell elements in a plan view.

  In one embodiment, the bypass element is further arranged so as not to overlap the inner lead in a plan view.

  In a certain embodiment, the said bypass element is incorporated in the said terminal box, and the said terminal box is attached to the back surface side of the said back surface protection material.

  According to the solar cell module of the present invention, the hot spot cells and bypass elements, which are heat sources, are dispersed and arranged, thereby suppressing overheating by the hot spot cells and the bypass elements and eliminating foaming of the filler to generate power. A decrease in efficiency can be suppressed. Moreover, by suppressing these overheating, it can suppress that the inner lead which connects solar cell elements peels, and can improve the reliability of a solar cell module.

  Furthermore, it is preferable that the bypass element is disposed so as not to overlap with the inner leads connecting the solar cell elements in a plan view. The inner lead is made of a metal such as copper and has a higher coefficient of thermal expansion than silicon, which is the substrate of the solar cell element. For this reason, when high heat is applied to the inner lead, a high thermal stress is applied to the connecting portion of the inner lead, which tends to cause peeling. By disposing the bypass element so as not to overlap with the inner leads that connect the solar cell elements, it is possible to improve the reliability of the solar cell module by suppressing the peeling of the connecting portions of the inner leads.

  Hereinafter, the solar cell module of the present invention will be described with reference to the accompanying drawings.

  One Embodiment of the solar cell module of this invention is shown in FIGS. Fig.1 (a) is the top view which looked at an example of the solar cell module of this invention from the non-light-receiving surface side. The dotted line portion shown in FIG. 1A shows the internal structure when the solar cell module is seen through in plane. FIG.1 (b) is a schematic sectional drawing in the A-A 'line shown to the solar cell module of Fig.1 (a). FIG. 2 is a model diagram illustrating an example of electrical connection of the solar cell modules. And FIG. 3 is a perspective view which shows the laminated structure of a solar cell module.

  As shown in FIGS. 1 (a) and 1 (b), the solar cell module 1 of the present embodiment includes a translucent substrate 2, a solar cell matrix 3, a filler 4, a back surface protective material 5, a bypass element 6, The terminal box 7 and the frame 8 are included. The solar cell matrix 3 is sealed with a filler 4, and the filler 4 including the solar cell matrix 3 is sandwiched and protected between the translucent substrate 2 and the back surface protective material 5. Further, the periphery of these laminates is protected by a frame 8. Further, a terminal box 7 including a bypass element 6 is attached to the back surface side of the back surface protection material 5. In this specification, the light receiving surface side may be referred to as the front surface side, and the non-light receiving surface side may be referred to as the back surface side.

  The translucent substrate 2 may be any material that allows light to enter the solar cell element 311. For example, a white plate glass, tempered glass, double tempered glass, glass such as heat ray reflective glass, a substrate having high light transmittance made of polycarbonate resin, or the like is used. The thickness of the translucent substrate 2 is, for example, 3 mm to 5 mm. Specifically, a white plate tempered glass having a thickness of about 3 mm to 5 mm and a synthetic resin substrate (made of a polycarbonate resin or the like) having a thickness of about 5 mm are used.

  The solar cell matrix 3 is composed of linear solar cell strings 31 and horizontal wirings 32. The solar cell string 31 is formed by connecting a plurality of solar cell elements 311 linearly by inner leads 312.

  As the solar cell element 311, a crystalline solar cell element such as single crystal silicon or polycrystalline silicon, an amorphous silicon solar cell element, a Si thin film solar cell element, a CIS solar cell element, a CIGS solar cell element, or a dye-sensitized solar cell A battery element or the like is used. For example, when the solar cell element 311 is manufactured using a single crystal silicon substrate or a polycrystalline silicon substrate, a P layer containing a large amount of P-type impurities such as boron and an N layer such as phosphorus are formed inside the silicon substrate. A PN junction is formed by joining an N layer containing a large amount of type impurities. Further, an electrode made of silver paste or the like is formed on the front or back surface of the silicon substrate by a screen printing method or the like. The surface of the electrode is preferably coated with solder over almost the entire surface from the viewpoint of protecting the electrode and facilitating attachment of the inner lead 312.

  As the inner lead 312, for example, an entire surface of a wiring material such as a copper foil having a thickness of 0.1 mm to 0.5 mm is solder-coated by plating or dipping to about 20 to 70 μm.

  For example, as shown in FIG. 2, the horizontal wiring 32 is provided for the purpose of electrically connecting a plurality of solar cell strings arranged in parallel. As the horizontal wiring 32, the same material as that of the inner lead 312 is used.

  The filler 4 has a role of sealing the solar cell matrix 3. The filler 4 can be obtained, for example, by molding and cutting a thermosetting resin or a thermoplastic resin having a thermosetting property by adding a crosslinking agent into a sheet shape using a T-die and an extruder. As the thermosetting resin, for example, an acrylic resin, a silicone resin, an epoxy resin, or the like can be used. Further, as the thermoplastic resin, for example, a thermoplastic resin such as ethylene vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), ethylene-ethyl acrylate copolymer (EEA), etc. is used as a main component, and a crosslinking agent is added to them. Those containing s are preferably used. A crosslinking agent has a role which couple | bonds the molecules of a thermoplastic resin, For example, the organic peroxide which decomposes | disassembles at the temperature of 70-180 degreeC and generate | occur | produces a radical is used. Examples of the organic peroxide include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane and tert-hexylperoxypivalate. For example, the crosslinking agent is preferably contained at a ratio of about 1 part by mass with respect to 100 parts by mass of EVA. When the filler is EVA, foaming occurs when the temperature exceeds 150 ° C., and white turbidity occurs due to small bubbles.

  The back surface protective material 5 has a role of protecting the filler 4, for example, polyvinyl fluoride (PVF), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a laminate of two or more of these. The resin used is preferably used.

  As the bypass element 6, for example, a silicon diode, a Schottky diode, or the like is used. The bypass element 6 is provided for the purpose of a current bypass when a hot spot occurs. Therefore, it is electrically connected in parallel to the plurality of solar cell string groups. For example, in FIG. 2, one bypass element 6 is connected in parallel to two solar cell string groups. The bypass element 6 is generally disposed on the back side of the solar cell matrix 3 from the viewpoint of high photoelectric conversion efficiency. It may be present in the filler 4 on the back surface side of the solar cell matrix 3, or may be disposed on the back surface side of the back surface protection material. In general, as shown in FIG. 1, it is built in the terminal box 7 and arranged on the back surface side of the back surface protection material 5.

  In this invention, the said bypass element 6 is arrange | positioned so that it may overlap with the area | region formed between solar cell elements in planar perspective. By adopting such a structure, at the time of a hot spot, the hot spot cells serving as heat sources and the bypass element 6 are arranged in a distributed manner, and overheating of the hot spot cell and the bypass element 6 is suppressed, and the sun The temperature distribution of the battery module 1 can be leveled. Furthermore, by suppressing overheating, it contributes to suppression of white turbidity of the filler 4, suppression of decrease in power generation efficiency, and suppression of peeling of the inner leads 312, and the reliability of the solar cell module 1 can be improved.

  As described above, the disposition of the bypass element 6 only has to overlap with the region formed between the solar cell elements in plan perspective, and for example, the bypass element 6 is included in the region formed between the solar cell elements. Alternatively, a part of the bypass element 6 may overlap with a region formed between the solar cell elements. From the viewpoint of further suppressing overheating generated from the hot spot cell and the bypass element 6, 50% or more, preferably 90% or more of the bypass element 6 overlaps a region formed between the solar cell elements in a plan view. Is preferred.

  The bypass element 6 is preferably disposed so as not to overlap the inner lead 312 in a plan view. The inner lead is made of a metal such as copper and has a higher coefficient of thermal expansion than silicon, which is the substrate of the solar cell element. Therefore, when high heat is applied to the inner lead 312, higher thermal stress is applied to the connecting portion of the inner lead, causing peeling. By disposing the bypass element 6 so as not to overlap the inner lead 312 in a plan perspective, peeling of the inner lead can be suppressed and the reliability of the solar cell module can be improved.

  As the material of the terminal box 7, polyphenylene ether resin or the like is used. The terminal box 7 is generally provided on the back side of the solar cell matrix 3 from the viewpoint of making the solar cell module compact. Moreover, since the outer peripheral part of a solar cell module is used for clamping and fixing to a stand or attaching a frame, it is not preferable to provide a terminal box at these parts. The terminal box 7 is filled with a silicone resin or the like from the viewpoint of suppressing the ingress of water.

  The frame 8 is provided on the outer peripheral portion in order to reinforce the solar cell module. Generally, an anodized aluminum surface with an acrylic coating is used.

  The solar cell module of the present invention is manufactured by, for example, a method as shown in FIG. First, after arranging the solar cell strings in parallel, the horizontal wiring is appropriately connected to form the solar cell matrix 3. Next, the transparent substrate 2, the first filler 4, the solar cell matrix 3, the second filler 4, and the back surface protective material 5 are laminated in this order. At this time, the output from the solar cell matrix 3 is derived from the output lead outlet 51 provided in the back surface protective material 5. Finally, the output is connected to the terminal box 7 in which the bypass element is incorporated, and the terminal box 7 is attached to the back surface protective material 5 so that the bypass element 6 overlaps the region formed between the solar cell elements 311 in a plan view. . In this way, the solar cell module of the present invention is manufactured.

(simulation)
In order to confirm the effect of the present invention, a simulation was performed as follows. First, as shown in FIG. 4A, the solar cell module 1 used in this simulation has a light-transmitting substrate 2 (glass: t = 3.2 mm) and a filler 4 (EVA: t) in order from the light receiving surface side. = 1.6 mm), a back surface protective material 6 (PET: t = 0.2 mm) is laminated, and a solar cell element 311 (t = 0.2 mm) is included in the filler 4. Further, the solar cell module 1 (1001 mm × 533 mm) is configured by arranging solar cell elements 311 (156 mm × 78 mm × 0.2 mm) in 6 rows × 6 columns, and the space between the solar cell elements 311 is 5 mm. The terminal box 7 (120 mm × 75 mm × 1.8 mm) arranged on the back surface side of the back surface protective material 5 approximates a flat plate made of epoxy resin, and the bypass element 6 (13.5 mm × 10 mm × 5 mm) is in the center. Built in.

  In the model, as shown in FIG. 4B, the bypass element 6 is arranged below the region formed between the hot spot cells 311a. The simulation was performed under the following conditions with reference to the temperature of the solar cell module 1 installed in a certain area using such a model.

Light receiving side temperature: 46.7 ° C
Side temperature: 46.7 ° C
Non-light-receiving surface temperature: 86.7 ° C
Amount of heat generated from hot spot cell 311a: 14 [W]
Amount of heat generated from bypass element 6: 0.068 [W]
Solar radiation intensity irradiated to solar cell: 1024 W / m ²

  Moreover, as shown in FIG. 5, the simulation was performed under the same conditions as described above, except that a model in which the bypass element 6 was arranged below the hot spot cell 311a was used. The results are shown in Table 1 and FIG.

  From the results shown in Table 1 and FIG. 6, in the model (Example) in which the bypass element 6 is disposed below the region formed between the hot spot cells 311a, the bypass element 6 is disposed below the hot spot cell 311a. Compared to the model (comparative example), a temperature drop of 2.8 ° C. was observed for the solar cell element and 13.3 ° C. for the filler. Furthermore, in the temperature distribution of the hot spot cell 311a, the region exceeding 150 ° C. was 5% or less in the example, whereas it was 20% or more in the comparative example.

  From the above, it is possible to disperse the heat source by disposing the region formed between the bypass element and the solar cell element in a plan view, thereby preventing overheating and leveling the temperature distribution. Can do. Thereby, the cloudiness by the foaming of a filler and the fall of power generation efficiency can be suppressed. In addition, by suppressing the temperature difference from the surroundings from increasing, the hot spot cell itself is prevented from concentrating current generated by the surroundings due to the reverse bias to promote overheating, and the hot spot cell is damaged. Can be prevented.

  In addition, this invention is not limited to the said embodiment, Many corrections and changes can be added within the scope of the present invention.

It is drawing which shows the embodiment of the solar cell module of this invention, Fig.1 (a) is a top view seen from the non-light-receiving surface side, FIG.1 (b) is AA 'of Fig.1 (a). It is sectional drawing in a line. It is a model figure which shows the electrical connection of the solar cell module of this invention. It is a perspective view which shows the laminated structure of the solar cell module of this invention. It is drawing which shows the embodiment of the solar cell module of this invention, Fig.4 (a) is side part sectional drawing, FIG.4 (b) is a perspective view. It is drawing which shows the embodiment of the conventional solar cell module. It is drawing which shows the simulation result of a solar cell module. FIG. 6A is a solar cell module of the present invention, and FIG. 6B is a conventional solar cell module.

Explanation of symbols

1: Solar cell module 2: Translucent substrate 3: Solar cell matrix 4: Filler 5: Back surface protective material 6: Bypass element 7: Terminal box 8: Frame 31: Solar cell string 32: Horizontal wiring 311: Solar cell element 311a: Hot spot cell 312: Inner lead 51: Output lead outlet

Claims (3)

A translucent substrate, a solar cell string formed by connecting a plurality of solar cell elements linearly by inner leads, and a horizontal wiring provided so as to electrically connect the plurality of solar cell strings arranged in parallel. It is composed of a solar cell matrix sealed with a filler and a back surface protective material,
In a solar cell module that is arranged on the back side of the solar cell matrix and includes a bypass element that is electrically connected in parallel to the solar cell string,
The solar cell module, wherein the bypass element is disposed so as to overlap a region formed between the solar cell elements in a plan view.   2. The solar cell module according to claim 1, wherein the bypass element is further arranged so as not to overlap the inner lead in a plan view.   The solar cell module according to claim 1 or 2, wherein the bypass element is built in the terminal box, and the terminal box is attached to a back surface side of the back surface protection material.