JP2016127215A - Solar cell module and solar cell sealing resin used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module which can generate power with higher efficiency than conventional ones, and to provide a solar cell sealing resin used for the same.SOLUTION: The solar cell module includes: a solar cell 1 which converts received sunlight into electric power and has a texture structure 2 on a light-receiving surface side of the sunlight; a front electrode 11 and a back electrode 12 which are connected to the solar cell 1 and extract the electric power generated in the solar cell 1; and a first sealing resin 4 provided on the light-receiving surface side of the solar cell 1. The first sealing resin 4 contains a light scatterer 3 for scattering light in the first sealing resin 4. The haze of the first sealing resin 4 containing the light scatterer 3 is 52% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solar cell module and a solar cell sealing resin used therefor.

  The solar cell module is provided with solar cells and wiring for converting solar energy into electric power. And the solar cell module is normally comprised by the some photovoltaic cell being connected by the said wiring. The solar battery cell and the wiring are fixed by being sealed with a sealing resin.

  In a solar cell module, improvement in conversion efficiency from solar energy to electric power, that is, higher efficiency in power generation is desired. Therefore, a technique described in Patent Document 1 is known in relation to a technique for improving the efficiency of power generation. Patent Document 1 discloses a light scattering film for a solar cell in which scattering particles having a refractive index higher than that of a matrix resin are dispersed in a matrix resin, and the average particle diameter of the scattering particles is 1.0 μm or more and 10.0 μm or less. And a solar cell light scattering film having a refractive index difference between the matrix resin and the scattering particles of 0.05 to 0.30 and a solar cell including the same.

JP 2009-16556 A

  In order to increase the efficiency of power generation, the present inventors have studied and found that it is preferable to provide a texture structure (uneven structure) on the light irradiation surface of the solar battery cell. However, Patent Document 1 describes that when a texture structure is provided, conversion efficiency rather deteriorates. Therefore, it is desired to develop a solar ionization module that is intentionally provided with a texture structure for the solar cell described in Patent Document 1 and that can further increase the efficiency of power generation compared to the conventional one.

  The present invention has been made in view of such circumstances, and the problem to be solved by the present invention is that of a solar cell module capable of performing power generation more efficiently than before and a solar cell used therein. It is to provide a sealing resin.

  The present inventors have intensively studied to solve the above problems. As a result, the present inventors have found that the above-mentioned problem can be solved by providing a texture structure on the surface of the solar battery cell constituting the solar battery module and setting the haze of the sealing resin for sealing the solar battery cell within a predetermined range.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell module which can perform electric power generation more efficiently than before, and the sealing resin of the solar cell used for it can be provided.

It is a perspective view of the solar cell module of this embodiment, and is a figure which shows a part of its internal structure. It is the perspective view which decomposed | disassembled and showed the solar cell module of this embodiment. It is a top view of the solar cell module of this embodiment. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, and is a cross-sectional view of a portion including wiring in the vicinity of adjacent solar cells. FIG. 4 is a cross-sectional view taken along line B-B in FIG. 3 and is a cross-sectional view of a portion not including wiring in the vicinity of adjacent solar cells. It is a figure which shows the vicinity of the texture structure formed in the light-receiving surface of the photovoltaic cell in the solar cell module of this embodiment. In the solar cell module of this embodiment, it is a figure which shows the change of the light ray produced by a texture structure and a light-scattering body. It is a graph which shows the simulation result of the relationship between the haze of the 1st sealing resin containing a light-scattering body, and the improvement ratio of the power generation efficiency by a photovoltaic cell. It is a graph which shows the simulation result of the relationship between the particle | grain density | concentration of the light-scattering body contained in 1st sealing resin, and the haze of the 1st sealing resin containing a light-scattering body. It is a graph which shows the simulation result of the relationship between the total light transmittance of the 1st sealing resin containing a light-scattering body, and the haze of the 1st sealing resin containing a light-scattering body.

  Hereinafter, a form (this embodiment) for carrying out the present invention will be described with reference to the drawings as appropriate. In addition, each figure to refer is typical except a graph, and a part of member may be abbreviate | omitted and shown for convenience of explanation or illustration. Each member may be enlarged or reduced as appropriate for convenience of explanation or illustration.

  FIG. 1 is a perspective view of a solar cell module 100 of the present embodiment, and shows a part of its internal structure. In FIG. 1, for the sake of convenience, a part of the members is visualized (transparent) so that the internal structure of the solar cell module 100 can be easily grasped. The solar cell module 100 includes a plurality of solar cells 1 (six in the present embodiment, see FIG. 2, partially omitted in FIG. 1) and wirings 8 connecting them.

  The solar battery cell 1 converts solar energy of received sunlight into electric power that can be used by a power conversion element or the like. The solar cell 1 is composed of single crystal silicon, polycrystalline silicon, amorphous silicon, CIGS (compound composed of copper, indium, gallium and selenium), CIS (compound composed of copper, indium and selenium), a compound composed of cadmium telluride and the like. Etc. can be used. Although details will be described later, the first sealing resin 4 and the cover glass 5 provided on the front side of the solar battery cell 1 are made of a material capable of transmitting sunlight. Therefore, sunlight passes through the cover glass 5 and the first sealing resin 4 in this order from the front side, and reaches the light receiving surface (front side surface) of the solar battery cell 1.

  A texture structure 2 is formed on the front surface of the solar battery cell 1 in a portion other than the ribbon-shaped front electrode 11 (described later). Details of the texture structure 2 will be described later with reference to FIG.

  The wiring 8 connects adjacent solar cells 1 to each other. The wiring 8 is also used to connect the solar cell module 100 to a secondary battery or an external load (not shown). Details of these points will be described later with reference to FIG. The wiring 8 is made of a ribbon-like metal (for example, a solder-coated copper ribbon).

  A front electrode 11 is provided on the front surface of each solar cell 1, and a back electrode 12 is provided on the back surface. The front electrode 11 and the back electrode 12 are for taking out electric power generated in the solar battery cell 1. And each solar cell 1 is electrically connected by the front electrode 11 of the photovoltaic cell 1 and the back electrode 12 of the adjacent photovoltaic cell 1 being connected by the wiring 8. FIG. The front electrode 11 and the wiring 8 are connected to each other, and the back electrode 12 and the wiring 8 are connected by soldering or the like.

  The front electrode 11 is provided as a ribbon-shaped electrode on the light receiving surface side (front side) of the solar battery cell 1. That is, the front electrode 11 is provided only on a part of the light receiving surface on the light receiving surface side of the solar battery cell 1 so that the solar battery cell 1 can receive light. The front electrode 11 is made of, for example, silver. The width in the left-right direction of this ribbon-like electrode (bus electrode) is about 1.5 mm in this embodiment. Further, although not shown, a linear electrode (finger electrode) having a width of about 0.1 mm (width in the rearward direction) is provided in a direction perpendicular to the bus electrode. The bus electrode (front electrode 11) and the finger electrode are electrically connected, and the wiring 8 is connected to the bus electrode.

  On the other hand, unlike the front electrode 11, the back electrode 12 is provided as a flat electrode on the entire surface on the side opposite to the light receiving surface (back side) of the solar battery cell 1. The back electrode 12 is made of, for example, aluminum.

  FIG. 2 is an exploded perspective view showing the solar cell module 100 of the present embodiment. In FIG. 2, for convenience of illustration, all members are shown to have the same size (area in the left and right and frontward directions), and some members such as the wiring 8 are not shown. As shown in FIG. 2, the solar cell module 100 includes a cover glass 5, a first sealing resin 4 (including the light scatterer 3), a solar cell 1, a second sealing resin 7, and a back sheet from the front side. 6 (back member) is arranged in this order.

  Therefore, the solar cell module 100 can be manufactured as follows, for example. First, each solar cell 1 connected by the wiring 8 (not shown in FIG. 2) is placed on the second sealing resin 7 disposed on the surface of the back sheet 6. Then, the first sealing resin 4 and the cover glass 5 are placed thereon, the first sealing resin 4 and the second sealing resin 7 are heat-sealed, and the solar cells 1 and the like are sealed therebetween. By stopping, the solar cell module 100 can be manufactured.

  In the present embodiment, the cover glass 5 is made of a transparent material. By providing the cover glass 5, the light scatterer 3 and the first sealing resin 4 can be protected from wind and rain, and the durability of the solar cell module 100 can be enhanced. Therefore, the cover glass 5 is preferably excellent in both weather resistance and mechanical strength. Moreover, it is preferable that the cover glass 5 has the high transmittance | permeability of the light of the wavelength range 300nm-1100nm in which the sensitivity of the photovoltaic cell 1 is high. Furthermore, the surface of the cover glass 5 may be subjected to treatment such as antireflection. Considering these points, examples of the material of the cover glass 5 include normal glass and high transmittance glass (white plate glass) in which impurities such as iron are reduced from normal glass.

  The first sealing resin 4 includes the light scatterer 3 and allows the sunlight incident from the cover glass 5 to reach the light receiving surface of the solar battery cell 1. In the present embodiment, the first sealing resin 4 is made of a transparent material. In particular, the first sealing resin 4 preferably has a high light transmittance in the wavelength range of 300 nm to 1100 nm where the sensitivity of the solar battery cell 1 is high, similar to the cover glass 5 described above.

  Moreover, since the 1st sealing resin 4 adheres the photovoltaic cell 1 and the cover glass 5, it is preferable to be comprised with the material which has high intensity | strength and weather resistance. Therefore, as the first sealing resin 4, for example, EVA (ethylene vinyl acetate copolymer resin), PE (polyethylene), PVB (polyvinyl butyral), etc., and a mixture thereof are suitable. By using these resins, when the first sealing resin 4 and the second sealing resin 7 are heat-sealed in a state where the solar battery cell 1 is sandwiched, there is appropriate softness. Cheap. Also, the adhesion is improved. Furthermore, they have good weather resistance. These resins have a refractive index of about 1.5. The first sealing resin 4 may contain an ultraviolet absorber or the like as necessary.

  The thickness of the first sealing resin 4 is not particularly limited, but is, for example, 0.1 mm to 2 mm, preferably 0.2 mm to 1 mm, more preferably 0.3 mm to 0.7 mm. be able to. When the thickness of the first sealing resin 4 is within these ranges, the strength and weather resistance can be exhibited particularly well.

  In the solar cell module 100 of this embodiment, the haze of the first sealing resin 4 including the light scatterer 3 is 52% or less. This point will be described later with reference to FIGS. Incidentally, the haze of the first sealing resin 4 including the light scatterer 3 in the solar cell module 100 is measured for the first sealing resin 4 after extracting the first sealing resin 4 including the light scatterer 3. By doing so, it can be calculated.

  As described above, the light scatterer 3 disperses the light incident on the first sealing resin 4, the light reflected on the surfaces of the solar battery cell 1 and the front electrode 11, and the like in the first sealing resin 4. It is. Thereby, the incident light to the light-receiving surface of the photovoltaic cell 1 is increased. In addition, content of the light-scattering body 3 in the 1st sealing resin 4 is the quantity from which the haze of the 1st sealing resin 4 containing the light-scattering body 3 becomes 52% or less. This will be described later with reference to FIG.

  The material constituting the light scatterer 3 is preferably a material that is transparent and has a refractive index different from the refractive index of the first sealing resin 4. In addition, the inclusion of the light scatterer 3 causes the incident light in the first sealing resin 4 to be scattered such as reflection or refraction at the interface due to the difference in refractive index, and the direction thereof changes. Therefore, from the viewpoint of effectively obtaining scattering, the light scatterer 3 is preferably spherical. In addition, when the light scatterer 3 is spherical, the sphere diameter is preferably 0.5 μm or more and 150 μm or less. However, the light scatterer 3 does not have to be a perfect sphere, for example, the cross section is an ellipse. (For example, an egg shape) or an anisotropic shape such as a needle shape or a plate shape may be used. And in the case of these shapes, it is preferable that the length of the light-scattering body 3 in the major axis direction is 0.5 μm or more and 150 μm or less. In summary, although the light scatterer 3 is preferably spherical, the length of the longest part (or its diameter if spherical) is 0.5 μm or more and 150 μm or less, regardless of its shape. preferable.

  The light scatterer 3 is preferably an inorganic material or an organic material. For example, the inorganic particles made of oxides such as alumina, zirconium oxide, titanium oxide, barium titanate, and silica, and the first sealing resin 4 have a refractive index. Different organic particles are preferred. As the organic particles, for example, a silicone resin or a fluorine resin can be used on the low refractive index side, and a resin added with a halogen element, phosphorus, sulfur, or the like can be used on the high refractive index side. The light scatterer 3 may be subjected to a surface treatment for improving the affinity with the first sealing resin 4. By using inorganic particles made of an oxide as the light scatterer 3, a highly versatile material can be used, and the refractive index can be easily made desired. Further, by using organic particles as the light scatterer 3, the affinity with the first sealing resin 4 that is normally an organic material can be increased, and the strength of the first sealing resin 4 can be made more sufficient. can do.

  The light scatterer 3 is also preferably a hole in the first sealing resin 4. By applying holes as the light scatterer 3, no material other than resin is contained in the first sealing resin 4, so that the strength of the first sealing resin 4 is made more sufficient. Can do. Moreover, since it is not necessary to use the separate light-scattering body 3, manufacture of the solar cell module 100 can be made cheap. The refractive index of the holes as the light scatterer 3 is 1.

  When holes are applied as the light scatterer 3, the method of allowing the first sealing resin 4 to contain holes is arbitrary. For example, the resin constituting the first sealing resin 4 is melted, and the melted resin is vigorously stirred to contain bubbles, and then cured, whereby the first having the pores as the light scatterer 3 The sealing resin 4 can be produced. And the magnitude | size of the said hole is controllable by the intensity | strength of stirring, for example.

  Further, the light scatterer 3 is preferably a phosphor. Since the light scatterer 3 is a phosphor, in addition to the light scattering effect due to the difference in refractive index of the light scatterer 3 as described above, the light emitted by the excitation wavelength is scattered in all directions, that is, the phosphor emits light. By doing so, a light scattering effect can be obtained. Thereby, the power generation efficiency of the photovoltaic cell 1 can be further improved.

As the phosphor, those that are excited by light having a wavelength in the range of 250 nm to 600 nm and emit light having a wavelength in the range of 450 nm to 1100 nm are preferable. Such a phosphor may be an inorganic material or an organic material. Specific examples of phosphors composed of inorganic materials include CaS: Eu, (Sr, Ba, Mg) ₂ SiO ₄ : Eu, CaAlSiN ₃ : Eu, (Sr, Ca) AlSiN ₃ : Eu, Y ₃ Al _{5 O 12: Ce, (Sr,} Ba, Mg) 2 SiO 4: Eu, Ba 3 Sr 2 Si 3 O 12: Ce, CaSc 2 O 4: Ce, Y 2 O 2 S: Eu, ZnS: Cu, Al, BaMgAl ₁₀ O ₁₇ : Eu, Mg, Zn ₂ SiO ₄ : Mn and the like can be mentioned. Moreover, Eu (TTA) ₃ phen etc. are mentioned as a specific example of the fluorescent substance comprised with an organic material.

  The second sealing resin 7 fixes the solar battery cell 1 together with the first sealing resin 4. The material constituting the second sealing resin 7 can be the same as the first sealing resin 4 except that the light scatterer 3 is not included. However, the second sealing resin 7 may include the light scatterer 3 as necessary. Further, the thickness of the second sealing resin 7 is not particularly limited, but is preferably set to a thickness in the same range as the first sealing resin 4, for example. However, the thickness of the second sealing resin 7 does not necessarily have to be the same as the thickness of the first sealing resin 4.

  The back sheet 6 is disposed on the rearmost side of the solar cell module 100 and fixes the second sealing resin 7 and the like. The backsheet 6 is preferably made of a material having high weather resistance and high barrier properties. Specifically, the back sheet 6 is preferably made of, for example, polyethylene terephthalate, polyamide, polyvinyl fluoride resin, or a sheet in which these are laminated. In addition, inorganic fine particles may be dispersed in these as required.

  FIG. 3 is a top view of the solar cell module 100 of the present embodiment. In FIG. 3, the first sealing resin 4 and the cover glass 5 are not shown because they are transparent. A plurality (six in this embodiment) of solar cells 1 are provided separately from each other. Therefore, the second sealing resin 7 (because it is transparent and not shown in FIG. 3) and the back sheet 6 are visible around the solar battery cell 1 when viewed from above. .

  The three solar cells 1 arranged in the left-right direction from the back side toward the front side are connected in series by a set of wires 8. And the wiring 8 which connects the photovoltaic cells 1 mutually joins by the back side and this side, and is connected to the secondary battery and external load which are not shown in figure. As described above, in the solar cell module 100 of the present embodiment, six solar cells 1 are connected in series or in parallel. And the electric power generated in the solar cell module 100 is supplied to a secondary battery or an external load.

  FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, and is a cross-sectional view of a portion including the wiring 8 in the vicinity of the adjacent solar battery cell 1. As described above, the solar battery module 100 is manufactured by heat-sealing the solar battery cell 1 and the wiring 8 after being sandwiched between the first sealing resin 4 and the second sealing resin 7. . Therefore, the first sealing resin 4 is disposed above the solar battery cell 1 and the wiring 8. That is, in this embodiment, in addition to the upper side of the light receiving surface of the solar battery cell 1, the light scatterer is provided not only on the upper side of the wiring 8 but also on the part other than the upper part of the solar battery cell 1 (described later with reference to FIG. 5). 3 will exist. A second sealing resin 7 is disposed below the solar battery cell 1 and the wiring 8.

  As shown in FIG. 4, incident light enters the solar cell module 100 from the front side. And incident light permeate | transmits the cover glass 5 and the 1st sealing resin 4, and injects into the light-receiving surface of the photovoltaic cell 1. FIG. Further, some of the transmitted light is incident on the front surface of the wiring 8. Here, the wiring 8 is made of metal capable of reflecting light in the present embodiment, and incident light is reflected. And since the light scatterer 3 is disperse | distributed to the 1st sealing resin 4, the light reflected in the wiring 8 is scattered by the light scatterer 3, and a part of scattered light enters the photovoltaic cell 1. It will be incident.

  As described above, the first sealing resin 4 disposed on the front side of the solar battery cell 1 includes the light scatterer 3, so that not only the light directly incident on the light receiving surface of the solar battery cell 1 but also the wiring 8. The light incident on the front surface of the solar cell is also incident on the light receiving surface of the solar battery cell 1. Thereby, the power generation efficiency (conversion efficiency) of the solar cell module 100 is improved.

  Further, the power generation efficiency is improved while using aluminum, silver, or the like that is widely used as the wiring 8 or the front electrode 11. That is, in order to increase the amount of incident light on the light receiving surface of the solar battery cell 1, for example, a transparent electrode such as ITO may be used. However, the transparent electrode contains a rare metal and the moldability is not so good. Moreover, the transparent electrode is not completely transparent, and there is still a problem in light transmittance.

  Therefore, in this embodiment, the haze of the first sealing resin 4 is set to 52% or less (the reason for this range will be described later with reference to FIGS. 8 to 10) while providing the texture structure 2. Thus, conventional wiring and front electrodes that can reflect light (high reflectivity) can be used. Thereby, it is possible to obtain a sufficient power generation efficiency at a low cost, and it is possible to easily make the shape of the electrode or the like as desired. Examples of such a material capable of reflecting light include simple substances of various metals such as silver, copper, aluminum, iron and tin, laminates obtained by laminating metals, and metal materials such as alloys thereof.

  FIG. 5 is a cross-sectional view taken along the line BB in FIG. 3, and is a cross-sectional view of a portion not including wiring in the vicinity of adjacent solar cells. As described above, since the first sealing resin 4 and the second sealing resin 7 are heat-sealed, in the solar cell module 100, it is difficult to confirm their clear fusion interface. However, in FIG. 5, an interface with a clear fusion is illustrated for the convenience of illustration.

  As shown in FIG. 5, the first sealing resin 4 includes a portion that is in contact with the solar battery cell 1 and a portion that is in direct contact with the second sealing resin 7. Among these, the part (part where the photovoltaic cell 1 does not exist) that is in direct contact with the second sealing resin 7 corresponds to the part between the photovoltaic cells 1. And in the solar cell module 100 of this embodiment, in addition to the part which is contacting the photovoltaic cell 1 among the 1st sealing resin 4, it is also in the part which is contacting the 2nd sealing resin 7 directly. The light scatterers 3 are dispersed.

  Of the light incident on the solar cell module 100, the light that does not enter the solar cells 1 but passes between the solar cells 1 and enters the second sealing resin 7 is reflected on the backsheet 6. become. This is because the reflectance of the back sheet 6 is usually higher than the reflectance of the texture structure 2 of the solar battery cell 1. That is, the back sheet 6 reflects light not a little. Then, the light reflected on the back sheet 6 returns to the first sealing resin 4 and is scattered by the light scatterer 3. Thereby, the incident light to the light-receiving surface of the photovoltaic cell 1 increases like the light incident on the wiring 8, and the power generation efficiency (conversion efficiency) is improved.

  Further, a texture structure 2 is formed on the light receiving surface (front side) of the solar battery cell 1. The texture structure 2 will be described with reference to FIG.

  FIG. 6 is a view showing the vicinity of the texture structure 2 formed on the light receiving surface of the solar battery cell 1 in the solar battery module 100 of the present embodiment. In the present embodiment, the solar battery cell 1 is silicon-based. Therefore, in this embodiment, utilizing the fact that the etching rate of silicon has crystal orientation anisotropy, the texture structure 2 has an uneven shape (in this embodiment, the height in the front-rear direction is about 0.5 μm to 10 μm). Of pyramid). That is, the light receiving surface of the solar battery cell 1 has an uneven shape, and the uneven portion corresponds to the texture structure 2. Accordingly, the surface of the texture structure 2 is formed integrally with the light receiving surface of the solar battery cell 1, and light incident on the surface of the texture structure 2 (the surface of the mountain portion) is also used for power generation. Will contribute.

  In addition, although the texture structure 2 in the solar cell module 100 of the present embodiment has a pyramid shape as described above, the specific shape of the texture structure 2 is not limited to a pyramid shape (square pyramid). That is, the texture structure 2 is, for example, a cone or cylinder, a polygonal pyramid such as a triangular pyramid, a polygonal column such as a triangular prism, a wavy shape or an arc shape in a cross-sectional view, etc. Any shape is acceptable. Since the uneven texture structure is formed on the light receiving surface of the solar battery cell 1, the reflected light can travel in various directions when the incident light is reflected.

  FIG. 7 is a diagram illustrating changes in light rays generated by the texture structure 2 and the light scatterer 3 in the solar cell module 100 of the present embodiment. Light incident from the front side (incident light) passes through the cover glass 5 and the first sealing resin 4 and enters the light receiving surface of the solar battery cell 1. As light incident on the light receiving surface, there is light that directly enters from the front side (incident light A1). In addition, there is also light that is reflected by the surface of the texture structure 2 and is finally incident on the light receiving surface of the solar battery cell 1 while the direction is changed by the light scatterer 3 in the first sealing resin 4 (incident incident). Light A2). Then, there is also light that is reflected on the surface of the texture structure 2 and further absorbed by the surface of the texture structure 2 and used for power generation after the direction is changed by the light scatterer 3 (incident light A3). Further, as a result of being scattered in the incident direction by the light scatterer 3, there is also light that is incident on the interface between the cover glass 5 and air at an angle larger than the total reflection angle (incident light A4). The light incident on this interface is totally reflected, and the light after the total reflection is absorbed by the surface of the texture structure 2 and used for power generation (incident light A4).

  Thus, in the solar cell module 100 of the present embodiment, the light receiving surface is increased by the texture structure 2 to improve the light incident efficiency. In addition, even if the light is incident on the texture structure 2 but is reflected without being used for power generation, it is scattered by the light scatterer 3 or incident again on the surface of another texture structure 2, so that the light receiving surface or Incident efficiency of light entering the texture structure 2 is increased. That is, if the texture structure 2 is not formed, the reflected light can only be scattered by the light scatterer 3 in the solar battery cell 1, and there is room for improvement in power generation efficiency. Therefore, in the solar cell module 100 of the present embodiment, the amount of light used for power generation is increased by forming the texture structure 2 to improve the power generation efficiency.

  Moreover, the joint strength of the 1st sealing resin 4 and the photovoltaic cell 1 can be improved because the texture structure 2 is formed. That is, since the first sealing resin 4 and the solar battery cell 1 are completely different from each other, they are liable to peel off when simply joined. However, by forming an uneven structure like the texture structure 3, the bonding area between the first sealing resin 4 and the solar battery cell 1 (more specifically, the texture structure 2) can be increased. Becomes difficult to peel. Therefore, the durability of the solar cell module 100 can be improved.

  In addition to this, by preventing these peelings, it is possible to prevent an air layer from being formed between the first sealing resin 4 and the solar battery cell 1 that is generated along with the peeling. If such an air layer is formed, the refractive index changes, and the amount of light incident on the solar battery cell 1 and the texture structure 2 may be reduced. Therefore, by preventing these separations, light is more reliably incident on the solar cells 1 and the texture structure 2, and the power generation efficiency of the solar cell module 100 can be improved.

  Furthermore, the heat dissipation of the solar battery cell 1 can be improved by forming the texture structure 2 having an uneven shape. Here, the temperature of the solar cell module 100 may be as high as 60 ° C. or higher depending on the installation location. When the solar cell module 100 reaches a high temperature, the power generation efficiency of the solar cell 1 decreases. Therefore, improvement of the heat dissipation of the solar cell module 100 is also important for improving the power generation efficiency.

  Heat radiation is mainly performed from the back sheet 6 on the back side. In addition, in the solar cell module 100 of this embodiment, it is also performed from the light receiving surface side of the solar cell 1. That is, in the solar cell module 100 of this embodiment, since the texture structure 2 is formed on the light receiving surface of the solar cell 1, the surface area on the front side of the solar cell 1 is large. Therefore, heat can be radiated from the front side of the solar cell 1 having a large surface area, and heat dissipation is improved as compared with a conventional solar cell module that radiates heat mainly from the back side. Thereby, while improving power generation efficiency, it can suppress that the texture structure 2 becomes high temperature too much, and can improve durability.

  Note that reflection may be suppressed by applying an antireflection structure to the surface of the texture structure 2 (for example, a pyramidal uneven surface). By doing in this way, reflection can be suppressed and the light quantity utilized for electric power generation can be increased.

  By the way, in the solar cell module 100 of this embodiment, the 1st sealing resin 4 contains the light-scattering body 3, and the haze of the 1st sealing resin 4 containing the light-scattering body 3 is 52% or less. By doing in this way, the light reflected on the light receiving surface of the solar battery cell 1 and the surface of the texture structure 2 is scattered again, and re-incident on the light receiving surface of the solar battery cell 1 and the surface of the texture structure 2 is promoted. Yes. Here, the reason why the haze of the first sealing resin 4 including the light scatterer 3 is set to 52% or less will be described with reference to FIGS.

  FIG. 8 is a graph showing a simulation result of the relationship between the haze of the first sealing resin 4 including the light scatterer 3 and the power generation efficiency improvement ratio by the solar battery cell 1. The graph shown in FIG. 8 is calculated by performing a ray tracing simulation on the first sealing resin 4 including the light scatterer 3 shown in FIG.

  In this ray tracing simulation, crystalline silicon is used as the solar cell 1, the (111) surface of silicon (Si) with an antireflection film is used as the texture structure 2, and aluminum oxide particles (refractive index n = 1.77) as the light scatterer 3. , Particle size 1.4 μm), EVA (refractive index n = 1.5) as the first sealing resin 4, and normal glass as the cover glass 5. Moreover, as a light source, Airmass 1.5 (AM1.5) preferably used as a standard of sunlight spectrum was used. And the said simulation was performed by the parallel light entering perpendicularly | vertically with respect to the cover glass 5. FIG.

  Haze is the ratio of off-axis transmittance to total light transmittance expressed as a percentage. The haze value was calculated by reproducing the measurement optical system in “How to determine the haze of a plastic-transparent material (JIS K7361)” by ray tracing simulation. In this simulation, a sample was obtained by sandwiching both surfaces of the first sealing resin 4 in which the light scatterer 3 was dispersed between glass, and this sample was used as an object to be measured. The size of the haze was adjusted by the amount of the light scatterer 3 to be contained. This point will be described later with reference to FIG.

  The efficiency improvement ratio is the solar cell module in which the light scattering body 3 is included in the first sealing resin 4 with respect to the power generation efficiency of the solar cell module in which the light scattering body 3 is not included in the first sealing resin 4. The ratio of power generation efficiency at 100. Therefore, if the efficiency improvement ratio is larger than 1, the conversion efficiency of the solar cell module 100 is improved as compared with the conventional case. These solar cell modules are all manufactured under the same conditions except for the presence or absence of the light scatterer 3, and the texture structure 2 is formed on the surface of the solar cell 1 in any solar cell module. Is.

  As shown in FIG. 8, it was found that the efficiency improvement ratio exceeded 1 when the haze was 52% or less. In particular, it was found that if the haze is large at 52% or less, the power generation efficiency is improved. On the other hand, it was found that when the haze exceeds 52%, the efficiency improvement ratio is significantly reduced. This is because although the haze is large, light enters the first sealing resin 4, but the amount of the light scatterer 3 is too large, and the amount of light reaching the light receiving surface of the solar battery cell 1 is greatly reduced. However, the power generation efficiency is thought to have declined.

  On the other hand, when the haze was 0% or more and less than 2%, the efficiency improvement ratio was about 1, but an increase over 1 was observed. Therefore, improvement of power generation efficiency was recognized also in this range. However, the first sealing resin 4 that does not include the light scatterer 3 (that is, EVA alone) may have a haze of less than 2% due to scattering of the resin itself. In view of this, it has been found that the haze of the first sealing resin 4 including the light scatterer 3 is preferably 2% or more.

  FIG. 9 is a graph showing a simulation result of the relationship between the particle concentration of the light scatterer 3 included in the first sealing resin 4 and the haze of the first sealing resin 4 including the light scatterer 3. This simulation was performed in the same manner as the simulation conditions for calculating the graph of FIG. However, in this simulation, the refractive index n of the light scatterer 3 is set to n = 1.4 (silicone resin) and n = 1.51 (soda lime) in addition to the above-mentioned n = 1.77 (aluminum oxide). The same simulation was performed for four types of glass, n = 1.6 (epoxy resin), and n = 2.2 (zirconium oxide). In addition, as for these materials, all used the thing of a particle size comparable as the particle size of aluminum oxide.

As shown in FIG. 9, the haze increased as the particle concentration increased. That is, it was found that if the content of the light scatterer 3 in the first sealing resin 4 increases, the transparency of the first sealing resin 4 decreases. Here, as described with reference to FIG. 8, in the solar cell module 100 of the present embodiment, the haze of the first sealing resin 4 is set to 52% or less. Therefore, it was found that in order to reduce the haze to 52% or less, when the light scatterer 3 having a refractive index of 1.4 is used, the particle concentration may be 5000000 particles / mm ³ or less. Similarly, when the refractive index is 1.6, 4000000 / mm ³ or less, when the refractive index is 1.77, 1000000 / mm ³ or less, and when the refractive index is 2.2, 2000000 / mm ^3. It was found that the thickness should be ³ mm or less. On the other hand, when the light scatterer 3 having a refractive index of 1.51 was used, the haze was 2.6% even at the measured maximum value of 10000000 / mm ³ and was 52% or less.

In summary, when the refractive index difference Δn between the light scattering body 3 and the first sealing resin 4 (EVA; refractive index n = 1.5) is 0.1 or more, the haze is 52%. In order to achieve the following, it was found that the particle concentration should be 1000000 particles / mm ³ or less. On the other hand, when the refractive index difference Δn is less than 0.1 (for example, Δn = 0.01 when n = 1.51), it is considered that there is no upper limit. Therefore, as described with reference to FIG. 8, the haze is 52% or less, and a value as large as possible is preferable. However, in order to increase the haze, the content of the light scatterer 3 may be excessive. Get.

However, the content of the light scatterer 3 is preferably smaller in consideration of dispersibility in the first sealing resin 4. If the dispersibility is good, light can reach the entire light receiving surface of the solar battery cell 1 without unevenness, and the power generation efficiency can be made sufficiently good. Further, since the light scatterer 3 is uniformly dispersed in the first sealing resin 4, the durability of the first sealing resin 4 can be improved. Therefore, in consideration of these matters, in order to obtain a sufficient effect of improving the efficiency of the solar cell module 100, the particle concentration of the light scatterer 3 is set to 1000000 particles / mm, although it depends on the refractive index of the light scatterer 3. It was found that the refractive index difference Δn between the light scatterer 3 and the sealing resin 4 is preferably 0.1 or more, while the value is ³ or less.

  Moreover, in the silicon-type solar cell 1 used for the solar cell module 100 of the present embodiment, the reflectance of light having a wavelength of 300 nm to 450 nm tends to be high. Therefore, the light scatterer 3 preferably scatters light in this wavelength region. Therefore, in the 1st sealing resin 4 which disperse | distributed the light-scattering body 3, it is preferable that the haze of light with a wavelength of 300 nm-450 nm is larger than the haze of light with a wavelength of 450 nm-1100 nm. Therefore, as the refractive index difference Δn, the average refractive index difference with respect to light having a wavelength of 300 nm to 450 nm is larger than the average refractive index difference with respect to light having a wavelength of 450 nm to 1100 nm. The conversion efficiency of the solar cell module can be effectively improved.

  FIG. 10 is a graph showing a simulation result of the relationship between the total light transmittance of the first sealing resin 4 including the light scatterer 3 and the haze of the first sealing resin 4 including the light scatterer 3. This simulation was performed in the same manner as the ray tracing simulation conditions described with reference to FIG. However, the studied refractive indexes were four types: n = 1.4, n = 1.6, n = 1.77, and n = 2.2.

  As shown in FIG. 10, it was found that if the total light transmittance is large, the haze is small. That is, it was found that the amount of reflected light decreases when the amount of transmitted light is large. And as demonstrated with reference to FIG. 8, in the solar cell module 100 of this embodiment, the haze of the 1st sealing resin 4 is 52% or less. Therefore, as shown in FIG. 10, it has been found that in order to reduce the haze to 52% or less, the total light transmittance may be increased although it depends on the refractive index of the light scatterer 3.

  Specifically, for example, when the refractive index is 1.4, it has been found that the total light transmittance may be 99% or more. When the refractive index is 1.6, the total light transmittance is 98% or more, and when the refractive index is 1.77, the total light transmittance is 95% or more and the refractive index is 2.2. In this case, it has been found that the total light transmittance may be 75% or more. Therefore, it was found that the total light transmittance can be set low by using the light scatterer 3 having a refractive index as large as possible.

  As described above, when the texture structure 2 is formed on the surface of the solar battery cell 1, the haze of the first sealing resin 4 including the light scatterer 3 is set to 52% or less, so that the power generation efficiency is improved as compared with the conventional case. This can be improved (see FIG. 8). However, the haze of the first sealing resin 4 including the light scatterer 3 is preferably as close to 52% as possible.

  Moreover, when controlling the haze of the 1st sealing resin 4 to 52% or less, a haze is controllable by controlling the particle concentration (content) of the included light-scattering body 3 (refer FIG. 9). However, even if the content of the light scatterer 3 is the same, if the refractive index is different, a different haze is obtained. Therefore, the refractive index difference Δn, which is the difference between the refractive index of the light scatterer 3 and the refractive index of the resin constituting the first sealing resin 4, is the dispersibility of the light scatterer 3 in the first sealing resin 4. From the viewpoint of improving the viscosity, it is preferably 0.1 or more.

  Furthermore, when the haze of the first sealing resin 4 is controlled to 52% or less, the total light transmittance of the first sealing resin 4 varies depending on the refractive index, but is preferably as large as possible ( (See FIG. 10). Therefore, in consideration of the fact that the total light transmittance varies depending on the type of the resin, the haze of the first sealing resin 4 is set to 52 by selecting the type of the light scatterer 3 according to the type of the first sealing resin 4. % Or less.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Texture structure 3 Light scatterer 4 First sealing resin 5 Cover glass 6 Back sheet 7 Second sealing resin 8 Wiring 11 Front electrode 12 Back electrode 100 Solar cell module

Claims (12)

The received sunlight is converted into electric power, and the solar battery cell having a texture structure on the light receiving surface side of the sunlight,
A pair of electrodes connected to the solar cells and for extracting power generated in the solar cells;
A first sealing resin provided on the light receiving surface side of the solar battery cell,
The first sealing resin includes a light scatterer that scatters light in the first sealing resin,
The solar cell module according to claim 1, wherein a haze of the first sealing resin containing the light scatterer is 52% or less.   The solar cell module according to claim 1, wherein the light scatterer is an inorganic particle made of an oxide.   The solar light according to claim 1, wherein the light scatterer is a phosphor that is excited by light having a wavelength in a range of 250 nm to 600 nm and emits light having a wavelength in a range of 450 nm to 1100 nm. Battery module.   The solar cell module according to claim 1, wherein the light scatterer is a hole.   The solar cell according to any one of claims 1 to 4, wherein the first sealing resin includes at least one selected from the group consisting of ethylene vinyl acetate copolymer resin, polyethylene, and polyvinyl butyral. module. At least one of the pair of electrodes is disposed on the light receiving surface side,
The solar cell module according to claim 1, wherein the electrode disposed on the light receiving surface side is a metal electrode capable of reflecting light. A second sealing resin is provided on the back side opposite to the light receiving surface of the solar battery cell,
The solar battery cell is sealed with the first sealing resin and the second sealing resin,
The first sealing resin is composed of a portion in contact with the solar battery cell and a portion in direct contact with the second sealing resin.
5. The light scattering body is also included in a portion of the first sealing resin that is in direct contact with the second sealing resin. 6. The solar cell module according to.   5. The refractive index difference Δn between the refractive index of the light scatterer and the refractive index of the resin constituting the first sealing resin is 0.1 or more. The solar cell module according to item. 5. The content of the light scatterer contained in the first sealing resin is 1 million or less per 1 mm ³ of the first sealing resin. 5. The solar cell module according to.   The back surface member which can reflect light is provided in the opposite side to the side in which the said photovoltaic cell is provided of said 2nd sealing resin, The any one of Claims 1-4 characterized by the above-mentioned. The solar cell module according to claim 1. A plurality of the solar cells are provided,
The plurality of solar cells are electrically connected by wiring,
The solar cell module according to claim 1, wherein the wiring is made of a metal material capable of reflecting light. A resin member for sealing the solar battery cells;
A light scatterer that is contained in the resin member and scatters the light in the resin member,
A sealing resin for a solar cell for a solar cell module, wherein the resin member containing the light scatterer has a haze of 52% or less.

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