JP2018133556A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module capable of preventing breakage of tab wiring even when a protective substrate having the thermal expansion ratio different in the front and rear faces.SOLUTION: The solar cell module includes: a first protective substrate (28); a pair of sealing material layer (24, 26); a photoelectric conversion part having a solar cell (10) and a tab wiring (12) which are positioned between the pair of sealing material layers (24, 26); and a second protective substrate (20). The thermal expansion ratio of the first protective substrate (28) is different from that of the second protective substrate (20). In the first protective substrate (28) and the second protective substrate (20), the relationship between the thickness dof the sealing material layer which is positioned at the protective substrate side the thermal expansion ratio of which is smaller and the thickness dof the sealing material layer positioned at the protective substrate side the thermal expansion ratio of which is larger is 0<d<d.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a solar cell module, and more particularly to a solar cell module in which the thermal expansion coefficient of a protective substrate is different between the front and back sides.

  The solar cell module has, as a basic configuration, a first protective substrate, a first resin layer (encapsulant), a photoelectric conversion unit, a second resin layer (encapsulant), a second protective substrate, In this order. That is, the photoelectric conversion unit is protected by covering the front and back surfaces of the photoelectric conversion unit with the first protective substrate and the first resin layer, and the second resin layer and the second protective substrate. In such a configuration, in the photoelectric conversion unit, a plurality of solar cells are arranged in a matrix, and adjacent solar cells are electrically connected by tab wiring (see, for example, Patent Document 1).

  In recent years, in order to reduce the weight of a solar cell module, it has been proposed to use a resin substrate instead of a glass substrate. And since the optimal material according to each role is selected in the front and back protection board, the material of the front and back protection board has come to differ.

JP 2013-145807 A

  As described above, the solar cell module can be made much lighter than that using a glass substrate by using any one of the first and second protective substrates as a resin. However, the resin substrate expands greatly as the temperature rises as compared with the glass substrate, and a problem is a decrease in reliability due to tab wiring disconnection due to the expansion.

  The present invention has been made in view of such problems of the prior art. And the objective of this invention is providing the solar cell module which can prevent problems, such as tab wiring disconnection, even if it is a case where the protection board from which a thermal expansion coefficient differs in front and back is used.

The solar cell module which concerns on the 1st aspect of this invention is a photovoltaic cell located between a 1st protective substrate, a pair of sealing material layer, and a pair of said sealing material layer in order from the light-receiving surface side. And a photoelectric conversion part having a tab wiring, and a second protective substrate. The first protective substrate is made of resin, and the first protective substrate and the second protective substrate have different coefficients of thermal expansion. Further, the thickness d ₁ of the sealing material layer among thermal expansion coefficient of the first protective substrate and the second protective substrate is positioned in a small protective substrate side, the sealing material layer located large protective substrate coefficient of thermal expansion the relationship between the thickness _{d 2} is _{0 <d} 1 _{<d 2.}

A solar cell module according to a second aspect of the present invention includes a photovoltaic cell having a first protective substrate, a pair of encapsulant layers, and a solar cell and a tab wiring located between the pair of encapsulant layers. A conversion unit and a second protective substrate are included. The first protective substrate and the second protective substrate have different coefficients of thermal expansion. Of the first protective substrate and the second protective substrate, the thickness d ₁ of the sealing material layer located on the side of the protective substrate having the smaller thermal expansion coefficient, and the sealing material located on the side of the protective substrate having the larger thermal expansion coefficient The relationship with the layer thickness d ₂ is 0 <d ₁ <d ₂ .

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the protective substrate from which a thermal expansion coefficient differs in front and back is used, it can provide the solar cell module which can prevent problems, such as tab wiring disconnection.

It is a top view which shows the solar cell module which concerns on the 1st Embodiment of this invention. It is sectional drawing along the AA line of FIG. It is sectional drawing along the BB line of FIG. It is sectional drawing of the solar cell module of the form different from FIG. It is sectional drawing of the solar cell module of the form different from FIG. It is a fragmentary sectional view which shows another form of the groove | channel provided in the 2nd protective substrate. It is a top view of the 2nd protection board. It is the top view seen from the (A) 2nd protection board side of the solar cell module which concerns on the 2nd Embodiment of this invention, (B) It is sectional drawing along the AA line of (A) figure. It is a top view corresponding to Drawing 8 (A) showing another form of the 2nd protection board. It is sectional drawing corresponding to FIG. 8 (B) which shows another form of a 2nd protective substrate. It is sectional drawing along the BB line of FIG. It is sectional drawing which shows the form different from FIG. It is sectional drawing which shows the modification of 2nd Embodiment. It is sectional drawing which shows the state of the outer surface of a 2nd protective substrate. It is a fragmentary sectional view showing an important section of a modification of the 2nd protection board.

<Solar cell module>
Hereinafter, the solar cell module according to the present embodiment will be described with reference to the drawings. FIG. 1 is a top view of the solar cell module 100. As shown in FIG. 1, the solar cell module 100 of the present embodiment is rectangular in a plan view, and a rectangular coordinate system including an x axis, a y axis, and a z axis is defined. The x axis and the y axis are orthogonal to each other in the plane of the solar cell module 100. The z axis is perpendicular to the x axis and the y axis and extends in the thickness direction of the solar cell module 100. Further, the positive directions of the x-axis, y-axis, and z-axis are each defined in the direction of the arrow in FIG. 1, and the negative direction is defined in the direction opposite to the arrow. Of the two main surfaces forming the solar cell module 100 and parallel to the xy plane, the main plane arranged on the positive direction side of the z-axis is a “light-receiving surface”. The main plane disposed on the negative direction side of the z-axis is the “back surface”. The “light receiving surface” means a surface on which light is mainly incident, and the “back surface” may mean a surface opposite to the light receiving surface. Further, the positive direction side of the z-axis may be referred to as “light-receiving surface side”, and the negative direction side of the z-axis may be referred to as “back surface side”.

  “Upper” in the above description may be on the positive side of the z axis or on the negative side of the z axis. Furthermore, “substantially” indicates that they are different within the error range, that is, substantially the same.

  The solar cell module 100 includes a plurality of solar cells 10, a plurality of tab wires 12, and a plurality of connection wires 14.

Each of the plurality of solar cells 10 absorbs incident light and generates photovoltaic power.
The solar battery cell 10 is made of, for example, a semiconductor material such as crystalline silicon, gallium arsenide (GaAs), or indium phosphorus (InP). The structure of the solar battery cell 10 is not particularly limited, but here, as an example, it is assumed that crystalline silicon and amorphous silicon are stacked.

  Although omitted in FIG. 1, a plurality of finger electrodes extending in the x-axis direction parallel to each other and extending in the y-axis direction so as to be orthogonal to the plurality of finger electrodes are provided on the light receiving surface and the back surface of each solar cell 10. A plurality of, for example, two bus bar electrodes are provided. The bus bar electrode connects each of the plurality of finger electrodes.

The plurality of solar cells 10 are arranged in a matrix on the xy plane. Here, four solar cells 10 are arranged in the x-axis direction (short direction in the rectangular shape), and five solar cells 10 are arranged in the y-axis direction (longitudinal direction in the rectangular shape).
In addition, the number of the photovoltaic cells 10 arranged in the x-axis direction and the number of the photovoltaic cells 10 arranged in the y-axis direction are not limited to these. The five solar cells 10 arranged side by side in the y-axis direction are connected in series by the tab wiring 12 to form one solar cell string 16. Furthermore, as described above, since the four solar cells 10 are arranged in the x-axis direction, four solar cell strings 16 extending in the y-axis direction are arranged in parallel in the x-axis direction. Moreover, the solar cell string 16 may show only the some photovoltaic cell 10, and may show the combination of the some photovoltaic cell 10 and the some tab wiring 12. FIG.

  In order to form the solar cell string 16, the tab wiring 12 electrically connects the bus bar electrode on one light receiving surface side of the adjacent solar cells 10 and the bus bar electrode on the other back surface side. That is, the adjacent solar cells 10 are electrically connected to each other by the tab wiring 12. The tab wiring 12 is an elongated metal foil. For example, a copper foil coated with solder or silver is used. Resin is used for connection between the tab wiring 12 and the bus bar electrode. This resin may be either conductive or non-conductive, but the tab wiring 12 and the bus bar electrode need to be electrically and mechanically connected. That is, in the latter case, the tab wiring 12 and the bus bar electrode are electrically connected by being directly connected. The tab wiring 12 and the bus bar electrode may be connected by using solder instead of resin.

  Further, a plurality of connection wires 14 extend in the x-axis direction on the positive and negative sides of the y-axis of the solar cell string 16, and the connection wires 14 electrically connect two adjacent solar cell strings 16. Connecting. In the above configuration, each of the solar battery cell 10 and the solar battery string 16 may be a “photoelectric converter”, and a combination of the plurality of solar battery strings 16 and the connection wiring 14 is a “photoelectric converter”. Also good.

The solar cell module of the present embodiment includes a first protective substrate, a pair of sealing material layers, a photoelectric conversion unit having a solar battery cell and a tab wiring, which is positioned between the pair of sealing material layers, 2 protective substrates. The first protective substrate and the second protective substrate have different coefficients of thermal expansion. Further, the thickness d ₁ of the sealing material layer where the first protective substrate and among thermal expansion coefficient of the second protective substrate is positioned in a small protective substrate side, a sealing material layer located thermal expansion coefficient is large protective substrate side The relationship with the thickness d ₂ of the above is 0 <d ₁ <d ₂ .

  2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB in FIG. The solar cell module 100 includes a solar cell 10, a tab wiring 12, a connection wiring 14, a solar cell string 16, a second protective substrate 20, a sealing material layer 24, a sealing material layer 26, and a first protective substrate 28. . That is, the photoelectric conversion unit having the solar battery cell 10 and the tab wiring 12 is located between the pair of sealing material layers 24 and 26, and the first protective substrate 28 and the second protective substrate 20 are arranged above and below the photoelectric conversion unit. Has been. Also, the lower side (second protective substrate 20 side) in FIGS. 2 and 3 corresponds to the back surface side, and the upper side (first protective substrate 28 side) corresponds to the light receiving surface side.

2 and 3, the first protective substrate 28 and the second protective substrate 20 have different thermal expansion coefficients. Here, the first protective substrate 28 is made of polycarbonate, and the second protective substrate 20 is made of glass epoxy resin. In this case, the first protective substrate 28 has a higher coefficient of thermal expansion than the second protective substrate 20. Then, the thickness of the sealing material layer 24 having a thermal expansion rate is located in a small second protective substrate 20 is d _1, the thickness of the sealing material layer 26 located thermal expansion coefficient larger side first protective substrate 28 Is d ₂ , and the sealing material layers 24 and 26 are provided so that d ₁ <d ₂ . As described above, the thickness of each sealing material layer is set as described above based on the difference in coefficient of thermal expansion between the first protective substrate 28 and the second protective substrate 20, thereby preventing tab wiring from coming off or breaking. Can do. This is because when the first protective substrate 28 and the second protective substrate 20 are thermally expanded, the sealing material layers 24 and 26 made of a flexible material located on those sides can follow the thermal expansion of each protective substrate. Because. Specifically, the sealing material layer 26 having a thickness d ₂ larger than the thickness d ₁ of the sealing material layer 24 positioned on the second protection substrate 20 side is provided on the first protection substrate 28 side having a higher coefficient of thermal expansion. Is located. Then, a sealing material layer 26 having a larger thickness is located on the first protective substrate 28 side where thermal expansion is larger than that of the second protective substrate 20. Therefore, the thermal expansion of the first protective substrate 28 can be absorbed more greatly, and the difference in thermal expansion between the first protective substrate 28 and the second protective substrate 20 can be offset. Therefore, the load on the tab wiring 12 of the photoelectric conversion unit due to the difference in thermal expansion between the first protective substrate 28 and the second protective substrate 20 is reduced, and the tab wiring 12 can be prevented from being detached or broken.
Each layer will be described in turn below. In the following description, the first protective substrate will be described as a protective substrate on the light receiving surface side, and the second protective substrate will be described as a protective substrate on the opposite side (back side).

[First protective substrate]
The first protective substrate 28 is disposed on the light receiving surface side of the solar cell module 100 and protects the surface of the solar cell module 100. For the first protective substrate 28, for example, a polycarbonate resin having transparency (transparent or translucent) is used.
Although the thickness of the 1st protective substrate 28 is not specifically limited as long as it plays the role which protects the surface of the solar cell module 100, it is preferable to set it as 0.1-10 mm, and it is more preferable to set it as 0.5-5 mm. By setting it as such a range, the solar cell module 100 can be protected appropriately and light can be efficiently reached to the solar cell 10.
The first protective substrate 28 is formed in a rectangular plate shape having a thickness of 1 mm, for example, but is not limited thereto. Polycarbonate resin is a kind of thermoplastic plastic, and its tensile elastic modulus is 2.3 to 2.5 GPa.
Here, the tensile modulus E is a proportional constant of the strain σ and the stress ε in the coaxial direction, and is expressed as follows.
E = σ / ε
The tensile elastic modulus is also called Young's modulus.
The thermal expansion coefficient of the first protective substrate 28 is not particularly limited, but the solar cell module of the present embodiment is intended for the first protective substrate 28 and the second protective substrate 20 that have different thermal expansion coefficients. .

[Encapsulant layer]
The pair of sealing material layers 24 and 26 seals the photoelectric conversion unit including the solar battery cell 10 and the tab wiring. The sealing material layer 24 is disposed on the positive side (upper side) of the z-axis of the second protective substrate 20, and the sealing material layer 26 is disposed on the negative direction side (lower side) of the first protective substrate 28. ).

  As the sealing material layer 26, for example, a gel having a tensile modulus of 0.001 MPa to 1 MPa and a loss coefficient of 0.1 to 0.52 is used. Such a gel is, for example, a silicon gel, an acrylic gel, a urethane gel, or the like. For silicon gel, the tensile modulus is 0.022 MPa. The loss coefficient is a ratio G ″ / G ′ between the storage shear modulus (G ′) and the loss shear modulus (G ″) and is represented by tan δ. The loss factor indicates how much energy the material absorbs when the material deforms. The larger the value of tan δ, the more energy is absorbed. This loss factor is measured by a dynamic viscoelasticity measuring device. The sealing material layer 26 is formed of a rectangular sheet material having translucency and having a surface with a slightly small size in the xy plane of the first protective substrate 28. Note that the sealing material layer 26 may be liquid.

  As the sealing material layer 24, for example, a thermoplastic resin such as a resin film such as EVA, PVB (polyvinyl butyral), or polyimide is used. A thermosetting resin may be used. Here, especially EVA is used. For EVA, the tensile modulus is 0.01 to 0.25 GPa and the loss factor is 0.05. The sealing material layer 24 is formed of a rectangular sheet material having translucency and having a surface having substantially the same dimensions as the xy plane of the first protective substrate 28.

  As described above, the sealing material layers 24 and 26 have been described separately, but the same material may be used.

As described above, when the first protective substrate 28 has a larger coefficient of thermal expansion than the second protective substrate 20 as described above, the thickness of the pair of sealing material layers 24 and 26 is set as follows. That is, the thickness of the sealing material layer 24 positioned on the second protective substrate 20 side having a small coefficient of thermal expansion is d ₁ , and the thickness of the sealing material layer 26 positioned on the side of the first protective substrate 28 having a large coefficient of thermal expansion is d. when a _{2 is} set to be d 1 _{<d 2.} In this case, it is preferable to set so that d ₂ / d ₁ ≦ 1.2.

As described above, the solar cell string 16 is formed by connecting a plurality of solar cells 10 arranged in the y-axis direction (rectangular longitudinal direction) by the tab wiring 12.
The connection wiring 14 is connected to the positive side end and the negative side end of the y axis of the solar cell string 16. Such connection wiring 14 and solar cell string 16 are arranged on the negative side of the z-axis of the sealing material layer 26. Each of the plurality of solar cells 10 is formed in a flat plate shape having a light receiving surface and a back surface. In such a configuration, when a load is applied from above in FIGS. 2 and 3, the first protective substrate 28 and the sealing material layers 24 and 26 are buffered to suppress damage to the solar cell module 100. Yes.

[Second protective substrate]
The second protective substrate 20 is disposed on the negative direction side of the z-axis of the sealing material layer 24. The second protective substrate 20 protects the back side of the solar cell module 100. The second protective substrate 20 is preferably made of a fiber reinforced resin including GFRP (Glass Fiber Reinforced Plastics), CFRP (Caron Fiber Reinforced Plastics), and cellulose nanofibers. As the GFRP, for example, a glass epoxy resin (an example of a strength-enhancing fiber-body mixed resin) is used. Since the glass epoxy resin has a tensile elastic modulus of 20 to 25 GPa, the tensile elastic modulus of the first protective substrate 28 is made larger than the tensile elastic modulus of the second protective substrate 20.

  Further, a polycarbonate resin may be used for the second protective substrate 20, similarly to the first protective substrate 28. In that case, the second protective substrate 20 is formed to be thicker in the z-axis direction than the first protective substrate 28. That is, in this case, the second protective substrate 20 is higher in strength (rigidity) than the first protective substrate 28, but in the present embodiment, the second protective substrate 20 is the first protective substrate 28. The strength (rigidity) may be lower. Further, the second protective substrate 20 made of such a material has a smaller coefficient of thermal expansion than the first protective substrate 28.

  The thickness of the second protective substrate 20 is not particularly limited, but is preferably 0.01 mm or more and 10 mm or less, more preferably 0.05 mm or more and 5.0 mm or less, and 0.07 mm or more and 1.0 mm or less. More preferably it is. In particular, in the case of a fiber reinforced resin, the diameter of one fiber is preferably the lower limit of the thickness. By setting the thickness of the second protective substrate 20 in such a range, the deflection of the second protective substrate 20 can be suppressed, and the solar cell module 100 can be further reduced in weight.

  In the solar cell module of the present embodiment, it is preferable that at least one of the first protective substrate and the second protective substrate is made of resin for weight reduction.

In the solar cell module of the present embodiment, tab wiring is provided in a region facing the tab wiring of the protective substrate located on the sealing material layer side having a thickness of d ₁ out of the first protective substrate and the second protective substrate. It is preferable that a groove extending in the longitudinal direction is formed. As described above, in the solar cell module of the present embodiment, the thickness of the sealing material layer located on the side of the protective substrate having a small thermal expansion coefficient among the first protective substrate 28 and the second protective substrate 20 is formed thin. . Therefore, it is assumed that stress concentrates on the solar battery cell 10. Therefore, it is possible to relieve stress concentrated on the solar cells by forming a groove extending in the longitudinal direction of the tab wiring in a region facing the tab wiring on the protective substrate side where the thickness of the sealing material layer is reduced. it can.

  FIG. 4 shows a form in which the above grooves are formed. FIG. 4 is different from FIG. 3 in that the groove 30 is formed in the opposing region of the tab wiring 12. That is, as described above, the sealing material layer 24 is formed thinner than the sealing material layer 26, and the grooves 30 are formed in the second protective substrate 20 located on the sealing material layer 24 side. .

Moreover, among the first protective substrate and the second protective substrate, in a region where the thickness is the wiring member facing the protection substrate positioned sealing material layer side of d _2, a groove extending in the longitudinal direction of the wiring member formed It is preferable that Such a configuration is shown in FIG. In Figure 5, in a region where the thickness is opposed to the wiring member 12 of the first protective substrate 28 is located in the sealing material layer 26 side of d _2, a groove 32 extending in the longitudinal direction of the wiring member 12 is formed Yes. Thus, by forming a groove in both the first protective substrate 28 and the second protective substrate 20, the stress concentrated on the solar battery cell 10 can be further relaxed.

  The cross-sectional shape of the grooves 30 and 32 formed in at least one of the first protective substrate 28 and the second protective substrate 20 is preferably trapezoidal or semi-elliptical. The cross-sectional shapes of the grooves 30 and 32 in FIGS. 4 and 5 are rectangular. On the other hand, when the trapezoid as shown in FIG. 6A or the semi-elliptical shape as shown in FIG. Can be suppressed.

  It is preferable that the edge portion of the groove is formed in an arc shape, that is, a rounded shape. The edge portion is, for example, a circled portion in FIGS. 6 (A) and 6 (B). By forming this part in an arc shape, it is possible to increase the fluidity of the sealing material, which is the material of the sealing material layer, and to generate bubbles as well as to make the cross-sectional shape of the groove trapezoidal or semi-elliptical. Can be suppressed.

The width of the groove in the direction orthogonal to the longitudinal direction of the tab wiring 12 is preferably larger than the width of the tab wiring 12. By doing in this way, it becomes easy to spread the sealing material of a sealing material layer widely, and it can suppress that air remains. Alternatively, the tolerance of variations due to manufacturing errors can be widened for the positions of the tab wiring 12 and the grooves 30 and 32. Specifically, when the width in the direction orthogonal to the extending direction of the grooves 30 and 32 is W ₁ and the width of the tab wiring 12 is W ₂ , it is preferable that 1 ≦ W ₁ / W ₂ ≦ 5.

  The grooves 30 and 32 as described above can be formed in the entire opposing region of the tab wiring 12 in the first protective substrate 28 or the second protective substrate 20, but the region facing the region where the solar battery cell 10 does not exist. The grooves 30 and 32 are preferably not formed. Such a configuration is shown in FIG. FIG. 7 is a top view of the second protective substrate 20, and the groove 30 is formed in the region facing the tab wiring 12, but the region between the solar cell 10 and the adjacent solar cell 10, that is, the solar cell. The groove 30 is not formed in the region 34 facing the region where the battery cell 10 does not exist. By setting it as such a structure, generation | occurrence | production of a bubble between the adjacent photovoltaic cells 10 can be suppressed.

  On the other hand, the grooves 30 and 32 as described above are preferably formed simultaneously with the formation of the first protective substrate 28 or the second protective substrate 20. By doing in this way, it is not necessary to form a groove | channel by another process after producing a 1st or 2nd protective substrate, and it contributes to manufacturing efficiency improvement.

  Next, a second embodiment will be described. In the solar cell module of the second embodiment, the protective substrate on the side opposite to the light receiving surface side (hereinafter referred to as “back side protective substrate”) of the first protective substrate and the second protective substrate is made of resin. And (1) an outer surface of the back surface side protective substrate, in which columnar reinforcing ribs extend in the longitudinal direction of the tab wiring, and / or (2) a frame along the outer periphery of the outer surface of the back surface side protective substrate. The reinforcing ribs extend.

  In the second embodiment, the mechanical strength of the second protective substrate 20 (back surface side protective substrate) on the side opposite to the light receiving surface side in the solar cell module 100 of the first embodiment is increased. That is, in the second embodiment, since the second protective substrate 20 is characterized, the second protective substrate 20 will be mainly described. The configuration other than the second protective substrate 20 (such as the photoelectric change portion and the first protective substrate) is not particularly touched, but is the same as that of the first embodiment, and the contents described in the first embodiment are valid as they are.

  FIG. 8 is a diagram illustrating an example of the second embodiment. As shown in FIG. 8B, the solar cell module of the second embodiment includes a second protective substrate 40, a pair of sealing material layers 42 between which the photoelectric conversion unit is disposed, and a first protective substrate 44. including. As shown in FIG. 8A, the second protective substrate 40 is formed with frame-shaped reinforcing ribs 40A and columnar reinforcing ribs 40B. Here, since FIG. 8A shows the entire solar cell module, it should originally be drawn in a rectangular shape as shown in FIG. 1, but is drawn in a square shape for convenience.

  As shown in FIG. 8, a frame-shaped reinforcing rib 40A extends along the outer periphery of the outer surface of the second protective substrate 40, and is on the outer surface of the second protective substrate 40 in the longitudinal direction of the tab wiring. Columnar reinforcing ribs 40B extend. In particular, the columnar reinforcing rib 40B functions as a beam of the second protective substrate 40 and can prevent the second protective substrate 40 from being deformed by heat. In addition, since the columnar reinforcing ribs 40B extend in the longitudinal direction of the tab wiring located in the pair of sealing material layers 42, the columnar reinforcing ribs 40B prevent the tab wiring from being broken. The frame-shaped reinforcing rib 40A and the columnar reinforcing rib B can be combined to prevent the second protective substrate 40 from being deformed.

  For example, the lower surface outer peripheral portion of the first protective substrate 44, the pair of sealing material layers 42, and the upper surface outer peripheral portion of the second protective substrate 40 are fixed by adhesive or resin welding. And when temperature rises with sunlight, 1st protective substrate 44 itself will extend greatly. However, since the second protective substrate 40 having a higher rigidity than the first protective substrate 44 and having a small coefficient of thermal expansion is fixed to the first protective substrate 44, the thermal expansion of the first protective substrate 44 and thereby The upward bending deformation is suppressed. As a result, disconnection of the tab wiring connecting a plurality of solar cells is suppressed, and a solar cell module with high reliability in operation is obtained.

  That is, the solar cell module of the second embodiment not only has a high mechanical strength but also the first protective substrate 44 and the pair of sealing material layers 42 (solar cell strings (solar cells, tabs) due to temperature rise. Wiring, connection wiring, etc.) greatly extend, thereby suppressing the disconnection of the tab wiring connecting a plurality of solar cells constituting the photoelectric conversion unit, and as a result, the reliability of the operation of the solar cell module is improved. Can be increased.

  As shown in FIG. 8, the columnar reinforcing rib 40 </ b> B preferably extends on the center line of the second protective substrate 40. This is because the mechanical strength of the second protective substrate 40 can be made uniform.

  Further, as shown in FIG. 8B, the thickness h2 of the columnar reinforcing rib 40B is preferably smaller than the thickness h1 of the frame-shaped reinforcing rib. If comprised in this way, space will be ensured on the outer side of the 2nd protective substrate 40, and not only weight reduction but the freedom degree of attachment to various apparatuses also improves.

  Moreover, it is preferable that the cross-sectional shape which makes the longitudinal direction of the columnar reinforcement rib 40B the normal line direction is a semi-elliptical shape. FIG. 10 shows such a configuration, and the cross-sectional shape of the columnar reinforcing rib 40C is a semi-elliptical shape. With such a configuration, the secondary moment of section can be increased.

  Furthermore, it is preferable that the central portion of the columnar reinforcing rib 40B in the longitudinal direction is thicker than both end portions. As shown in FIG. 11, the columnar reinforcing rib 40 </ b> B in FIG. 8 has the same thickness at the center portion and both end portions in the longitudinal direction. On the other hand, as for the 2nd columnar reinforcement rib 40D shown in FIG. 12, the center part of a longitudinal direction is thicker than both ends. By this columnar reinforcing rib 40D, the action of suppressing the expansion of the second protective substrate 40 in the longitudinal direction can be made gradually stronger gradually in the outward direction, with the central portion being strong.

Moreover, as shown in FIG. 9, it is preferable to have the recessed part (equipment recessed part 46) for attaching to another apparatus in the outer peripheral part of the frame-shaped reinforcement rib 40A provided in the 2nd protective substrate 40. As shown in FIG. As described above, since the device mounting recess 46 is provided, the mounting to various mounting portions is facilitated. That is, if a projection (not shown) to be attached to the roof of the house is provided, the projection can be easily attached at a fixed position only by fitting the projection into the device mounting recess 46.
In particular, the device mounting recess is preferably provided on the outer peripheral portion of the frame-shaped reinforcing rib 40A and on the longitudinal extension of the columnar reinforcing rib 40B. Thus, when the recessed part for apparatus attachment is provided and a solar cell module is attached to another apparatus, the rigidity of an attachment apparatus will be added as a reinforcement member. As a result, it is possible to effectively suppress the first protective substrate 44 and the second protective substrate 40 from extending in the longitudinal direction.

  In the solar cell module of the present embodiment, it is preferable that the frame-shaped reinforcing ribs 40A and the columnar reinforcing ribs 40B and the second protective substrate (back-side protective substrate) 40 are integrally formed. By integrally molding them, the weight can be reduced, the dimensional stability can be improved during manufacturing, and the frame-shaped reinforcing ribs 40A and the columnar reinforcing ribs 40B are not peeled off from the second protective substrate 40.

The above shows the form in which both the columnar reinforcing rib 40B and the frame-shaped reinforcing rib 40A are formed on the second protective substrate 40, but only one of the columnar reinforcing rib 40B and the frame-shaped reinforcing rib 40A is formed. May be. Moreover, not only one columnar reinforcing rib 40B but two or more may be formed. When two columnar reinforcing ribs 40B are formed, the columnar reinforcing ribs 40B are preferably arranged at equal intervals.

  FIG. 13: (A)-(D) shows the other form in 2nd Embodiment. 13A to 13D are cross-sectional views corresponding to FIG. 8B. In either case, the first protective substrate 44 has a curved shape in which the central portion in the longitudinal direction is upward and both sides thereof are downward. In FIG. 13A, the second protective substrate 40 is similarly curved according to the curvature of the first protective substrate 44. Also in this embodiment, the frame-shaped reinforcing rib 40A is provided on the second protective substrate 40.

  FIG. 13B is different from FIG. 13A in that a columnar reinforcing rib 40B having a central portion in the longitudinal direction that is thicker than both end portions is provided. The action of suppressing the expansion of the second protective substrate 40 in the longitudinal direction is strengthened by the columnar reinforcing ribs 40B, and the action is gradually relaxed toward both ends. In this embodiment, it is preferable that the central portion of the columnar reinforcing rib 40B does not protrude from a plane including the bottom surface of the frame-shaped reinforcing rib 40A. That is, in FIG. 13B, d> 0 is preferable.

  FIG. 13C is different from FIG. 13B in that the columnar reinforcing rib 40B is formed without being curved in the longitudinal direction.

  FIG. 13D is different from FIG. 13B in that the lower surface of the frame-shaped reinforcing rib 40A and the lower surface of the columnar reinforcing rib 40B are formed so as to coincide with each other.

  The form shown in FIGS. 13A to 13D is a form in which the surface of the solar cell module is curved. Even in such a form, the frame-shaped reinforcing rib A and the columnar reinforcing rib B can be formed on the second protective substrate 40, and even if the first protective substrate 44 is deformed, the presence of the second protective substrate 40 is sufficient. Further, it is possible to prevent the tab wiring of the photoelectric conversion part from being broken.

  On the other hand, the deformation can also be suppressed by making the outer surface of the second protective substrate 40 uneven. FIG. 14A shows a form in which the outer surface of the second protective substrate 40 is made flat, and FIG. According to the form shown in FIG. 14B, it is possible to suppress deformation in a state where the rigidity is improved and the weight is maintained by using the uneven shape.

  Furthermore, the variation of the shape of the edge part of the 2nd protective substrate 40 is shown in FIG. FIG. 15A is the same as the shape of the edge of the second protective substrate 40 shown in FIG. In FIG. 15B, the end portion of the second protective substrate 40 is protruded by a height corresponding to about half of the thickness of the pair of sealing material layers 42. In FIG. 15C, the end portion of the second protective substrate 40 protrudes by a height corresponding to the thickness of the pair of sealing material layers 42 and the first protective substrate 44, and the pair of sealing material layers 42 and 1 The end surface of the protective substrate 44 is protected. In FIG. 15D, the end portion of the second protective substrate 40 is protruded by a height corresponding to about half the thickness of the pair of sealing material layers 42, and the edge portion of the protruding portion is processed into an arc shape. ing. According to this embodiment, the protruding portion at the end of the second protective substrate 40 has a larger surface area than the protruding portion in FIG. 15B, and the adhesive force between the pair of sealing material layers 42 is improved. In FIG. 15E, the end portion of the second protective substrate 40 is the same as the thickness of the pair of sealing material layers 42. In this embodiment, the contact portion between the protruding portion at the end of the second protective substrate 40 and the first protective substrate 44 can be an adhesive portion. In FIG. 15F, the lower surface of the second protective substrate 40 is an inclined surface in the form of FIG. This form is effective when the place where the solar cell module is attached is an inclined surface.

  The solar cell module of the present embodiment further includes a terminal box (not shown), and it is preferable that the terminal box and one of the first protective substrate 44 and the second protective substrate 40 are integrally formed. In general, in a solar cell module, a current output from a photoelectric conversion unit is guided to an output cable to the outside via a terminal box provided with a terminal plate and the like. In the present embodiment, the terminal box is integrally formed with one of the first protective substrate 44 and the second protective substrate 40, whereby the terminal box is attached to the first protective substrate or the second protective substrate in a separate process. Therefore, manufacturing efficiency can be improved.

  Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited thereto.

[Example 1]
The static analysis of the stress at the time of changing temperature from 145 degreeC to 25 degreeC was performed with respect to the solar cell module of the layer structure shown in FIG. Details of each layer are shown below.
First protective substrate; thickness: 1 mm polycarbonate, coefficient of thermal expansion: 70 (× 10 ⁻⁶ K ⁻¹
)
Second protective substrate; thickness: 1.5 mm carbon fiber reinforced plastic (CFRP), coefficient of thermal expansion: 7 (× 10 ⁻⁶ K ⁻¹ )
Sealing material layer (first protective substrate side); thickness (d ₂ ): 0.6 mm ethylene-vinyl acetate copolymer (EVA)
Sealing material layer (second protective substrate side); thickness (d ₁ ): 0.2 mm ethylene-vinyl acetate copolymer (EVA)

(Evaluation)
It was -20.7 micrometer when the movement amount of the internal photovoltaic cell before and behind said temperature change was analyzed.

[Comparative Example 1]
Analysis of the solar cell module in the same manner as in Example 1 except that the thickness of the sealing material layer (first protective substrate side) and that of the sealing material layer (second protective substrate side) were the same (each 0.6 mm). Went. The results are shown in Table 1.

[Comparative Example 2]
The thickness (d ₂ ) of the sealing material layer (first protective substrate side) is 0.2 mm, and the thickness (d ₁ ) of the sealing material layer (second protective substrate side) is (0.6 mm). Analyzed the solar cell module in the same manner as in Example 1. The results are shown in Table 1.

  From Table 1, it can be seen that in Example 1, the amount of movement between cells was the smallest. That is, the movement of the cells can be suppressed by making the thickness of the sealing material layer on the second protective substrate side having a small coefficient of thermal expansion thinner than the sealing material layer on the side of the first protective substrate having a large coefficient of thermal expansion. It has been shown. As a result, it is presumed that tab wiring disconnection and breakage can be suppressed. On the other hand, in Comparative Examples 1 and 2, the amount of cell movement is large, and the tab wiring receives a large load, which is considered to cause disconnection and breakage.

[Example 2]
The analysis of the thermal stress when the temperature was changed from 25 ° C. to −40 ° C. was performed in the same manner as in Example 1 for the solar cell module having the following configuration.
Sealing material layer (first protective substrate side) thickness (d ₂ ): 0.6 mm
Sealing material layer (second protective substrate side) thickness (d ₁ ): 0.3 mm
In addition, the second embodiment is the same as the first embodiment except that a concave portion (width: 2 mm, depth: 0.2 mm) is formed in a region facing the tab wiring of the second protective substrate.
And the static analysis of the stress of tab wiring vicinity was performed.

[Comparative Example 3]
The same analysis was performed on the solar cell module having the same configuration as in Example 2 except that the concave portion was not formed on the second protective substrate.

  For Example 2 and Comparative Example 3, the analysis values of the minimum principal stress in the vicinity of the tab wiring on the solar battery cell were about -660 MPa and about -1100 MPa, respectively. That is, in Example 2 in which the concave portion was formed on the second protective substrate, the minimum principal stress was reduced by about 40% compared to Comparative Example 3 in which the concave portion was not formed. The positive analysis value represents tensile stress, and the negative analysis value represents compression stress. From this, it can be understood that the stress in the vicinity of the tab wiring is greatly reduced when the concave portion is formed at a predetermined position of the second protective substrate.

[Example 3]
The analysis of the thermal stress when the temperature was changed from 25 ° C. to −40 ° C. was performed in the same manner as in Example 1 for the solar cell module having the following configuration.
Sealing material layer (first protective substrate side) thickness (d ₂ ): 0.6 mm
Sealing material layer (second protective substrate side) thickness (d ₁ ): 0.3 mm
In addition, a concave portion (width: 2 mm, depth: 0.2 mm) was formed in the opposing region of the tab wiring of the second protective substrate. Further, a gel material layer (thickness: 1 mm, tensile elastic modulus: 0.022 MPa, thermal expansion coefficient: 860 (×) between the first protective substrate and the sealing material layer (first protective substrate side). 10 ⁻⁶ K ⁻¹ )) was formed. Except for these configurations, the second embodiment is the same as the first embodiment.
And static analysis of the stress near the tab wiring was performed.

[Comparative Example 4]
The same analysis was performed on the solar cell module having the same configuration as in Example 3 except that the concave portion was not formed on the second protective substrate.

  For Example 3 and Comparative Example 4, the analysis values of the maximum principal stress in the vicinity of the tab wiring on the solar battery cell were about 50 MPa and about 300 MPa, respectively. That is, in Example 3 in which the concave portion was formed in the second protective substrate, the maximum principal stress was reduced by about 80% compared to Comparative Example 4 in which the concave portion was not formed. From this, it can be understood that the stress in the vicinity of the tab wiring is greatly reduced when the concave portion is formed at a predetermined position of the second protective substrate.

10 Solar cell (photoelectric conversion part)
12 Tab wiring 14 Connection wiring 16 Solar cell string (photoelectric conversion part)
20 40 Second protective substrate 24 26 42 Sealing material layer 28 44 First protective substrate 30 32 Groove 46 Recessed portion 100 Solar cell module

Claims (20)

In order from the light-receiving surface side, a first protective substrate, a pair of sealing material layers, a photoelectric conversion unit having a solar battery cell and a tab wiring, located between the pair of sealing material layers, and a second protective substrate And
The first protective substrate is made of resin,
The first protective substrate and the second protective substrate have different coefficients of thermal expansion,
Of the first protective substrate and the second protective substrate, the thickness d ₁ of the sealing material layer located on the protective substrate side having the smaller thermal expansion coefficient, and the sealing located on the protective substrate side having the larger thermal expansion coefficient. solar cell module relationship between the thickness _{d 2} of the sealant layer is _{0 <d} 1 _{<d 2.} Of the first protective substrate and the second protective substrate, a groove extending in the longitudinal direction of the tab wiring in a region facing the tab wiring of the protective substrate located on the sealing material layer side having a thickness of d ₁ The solar cell module according to claim 1, wherein Further, the first protective substrate and of said second protective substrate, the tab wire facing the region of the protective substrate thickness is positioned in the sealing material layer side of d _2, extending in the longitudinal direction of the tab wires The solar cell module according to claim 2, wherein a groove is formed.    4. The solar cell module according to claim 2, wherein in the first protective substrate or the second protective substrate, the groove is not formed in a region facing a region where the solar cell does not exist.    The solar cell module according to any one of claims 2 to 4, wherein a cross-sectional shape of a groove formed in at least one of the first protective substrate and the second protective substrate is a trapezoid or a semi-elliptical shape.    The solar cell module according to claim 5, wherein an edge portion of the groove is formed in an arc shape.    The solar cell module according to any one of claims 2 to 6, wherein a width of the groove in a direction orthogonal to a longitudinal direction of the tab wiring is larger than a width of the tab wiring.    Of the first protective substrate and the second protective substrate, a protective substrate opposite to the light-receiving surface (hereinafter referred to as “back-side protective substrate”) is made of resin, and on the outer surface of the back-side protective substrate. The solar cell module according to claim 1, wherein a columnar reinforcing rib extends in a longitudinal direction of the tab wiring.    The solar cell module according to claim 8, wherein the columnar reinforcing rib extends on a center line of the back surface side protective substrate.    The solar cell module according to claim 8 or 9, wherein a shape of a cross section in which a longitudinal direction of the columnar reinforcing rib is a normal direction is a semi-elliptical shape.    The solar cell module according to any one of claims 8 to 10, wherein a central portion in the longitudinal direction of the columnar reinforcing rib is thicker than both end portions.    Of the first protective substrate and the second protective substrate, a protective substrate opposite to the light-receiving surface (hereinafter referred to as “back-side protective substrate”) is made of resin, and is formed on the outer surface of the back-side protective substrate. The solar cell module according to claim 1, wherein the frame-shaped reinforcing rib extends along the outer periphery.    The solar cell module of Claim 12 which has a recessed part for attaching to another apparatus in the outer peripheral part of the said frame-shaped reinforcement rib.    Furthermore, the solar cell module of any one of Claims 8-11 which has a frame-shaped reinforcement rib extended along the outer periphery of the outer surface of the said back surface side protective substrate.    The solar cell module according to claim 14, wherein a thickness of the columnar reinforcing rib is smaller than a thickness of the frame-shaped reinforcing rib.    The solar cell module according to claim 14 or 15, wherein the solar cell module has a concave portion for attaching to another device at a portion on an outer peripheral portion of the frame-shaped reinforcing rib and on a longitudinally extending line of the columnar reinforcing rib.    The solar cell module according to any one of claims 14 to 16, wherein the columnar reinforcing ribs, the frame-shaped reinforcing ribs, and the back surface side protective substrate are integrally formed.    Of the first protective substrate and the second protective substrate, the protective substrate opposite to the light receiving surface is a fiber reinforced resin including GFRP (Glass Fiber Reinforced Plastics), CFRP (Caron Fiber Reinforced Plastics), and cellulose nanofibers. The solar cell module according to claim 1, comprising:    The solar cell module according to claim 1, further comprising a terminal box, wherein the terminal box and one of the first protective substrate and the second protective substrate are integrally formed. A first protective substrate, a pair of sealing material layers, a photoelectric conversion part having a solar battery cell and a tab wiring located between the pair of sealing material layers, and a second protective substrate,
The first protective substrate and the second protective substrate have different coefficients of thermal expansion,
Of the first protective substrate and the second protective substrate, the thickness d ₁ of the sealing material layer located on the protective substrate side having the smaller thermal expansion coefficient, and the sealing located on the protective substrate side having the larger thermal expansion coefficient. solar cell module relationship between the thickness _{d 2} of the sealant layer is _{0 <d} 1 _{<d 2.}

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