JP2011181619A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module provided with an insulating substrate controlling the generation of warpage in the solar cell module. <P>SOLUTION: The solar cell module 1 has: a translucent substrate 2; a plurality of solar cells 5; and the insulating substrate 3 containing an electric wiring, wherein the plurality of cells 5 are sealed by a sealing layer 6 between the translucent substrate 2 and the insulating substrate 3. The translucent substrate 3 is a glass panel with a thickness of 2-4 mm, and the solar cells 5 are crystalline solar cells with a thickness of not more than 100-300 μm which are arranged staggered via gaps. This solar cell module 1 satisfies following formulas when the warpage (unit: μm) of the solar module 1 is Y, and the product of the elastic modulus E (unit: GPa) and the thermal expansion coefficient α (unit: ppm) of the insulating substrate 3 is X. A formula (1): Y≤12.88X+521.7. A formula (2): Y≥0.0324X+83.69. A formula (3): Y≤1,000, X≤700. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell module including an insulating substrate for fixing a back contact type solar cell including an electrode on a back surface.

In recent years, solar power generation, which is a power generation system using natural energy, has been rapidly spread. As shown in FIG. 8, the solar cell module for photovoltaic power generation includes a translucent substrate 120 disposed on the light receiving side, a back sheet 110 disposed on the back surface side, the translucent substrate 120 and the back. A large number of solar cells 130 sealed between the sheets 110 are included. The solar cell 130 is sandwiched and sealed between sealing films 140a and 140b such as an ethylene / vinyl acetate copolymer (EVA) film.
Conventionally, in a solar cell module, a large number of solar cells 130, 130,... Are electrically connected in series with a wiring material 150 having a width of 1 to 3 mm. Since the solar cell 130 is provided with a negative electrode (N-type semiconductor electrode) 131 on the front surface side which is the solar light-receiving surface 130a and a positive electrode (P-type semiconductor electrode) 132 on the back surface side, the solar battery cell 130 is connected with the wiring material 150. Then, the wiring material 150 overlapped on the light receiving surface 130a of the solar battery cell 130, and the area efficiency of photoelectric conversion tended to decrease.

In the arrangement of the electrodes 131 and 132 described above, since the wiring member 150 wraps around from the front side to the back side of the solar battery cell 130, the wiring member 150 may be disconnected due to a difference in thermal expansion coefficient of each member. .
Therefore, Patent Documents 1 and 2 propose a back contact type solar cell module in which both a positive electrode and a negative electrode are installed on the back surface of the cell. In this type of solar cell module, the solar cells are connected by a circuit of an insulating substrate disposed on the back side of the solar cells.
The back sheet of the solar cell module has a configuration in which a circuit layer is laminated on the surface of an insulating substrate, and solar cells are further laminated on the circuit layer. As a result, the light receiving area on the surface of the solar battery cell is not sacrificed, and a reduction in the area efficiency of photoelectric conversion can be prevented. Moreover, since it is not necessary to make the wiring material go around from the front side to the back side, disconnection of the wiring material due to the difference in thermal expansion of each member can be prevented.

JP 2005-11869 A JP 2009-111122 A

By the way, in the back contact type solar cell module as described above, the circuit layer is formed on the surface of the insulating substrate, and the solar cell is laminated on the circuit layer. When the battery module is exposed to a high temperature during use, the solar battery module may be warped due to the difference in linear expansion coefficient between the insulating substrate, the circuit layer, and the solar battery cell.
That is, since the insulating substrate has a higher linear expansion coefficient than the solar cell and the light-transmitting substrate, the insulating substrate expands more than the solar cell theory and the light-transmitting substrate at high temperatures. Accordingly, there has been a concern that a convex warp occurs on the back side of the solar cell module, leading to a failure.

  This invention is made | formed in view of such a subject, and it aims at providing the solar cell module provided with the insulating substrate which can suppress generation | occurrence | production of curvature in a solar cell module.

A solar cell module according to the present invention is a solar cell module having a translucent substrate, a solar cell, and an insulating substrate including electric wiring, and the translucent substrate is made of silicon oxide having a thickness of 2 mm to 4 mm. The solar battery module is composed of a crystalline solar battery cell having a thickness of 100 μm to 300 μm, and further satisfies the following formula.
Y ≦ 12.88X + 521.7 (1)
Y ≧ 0.0324X + 83.69 (2)
Y ≦ 1000, X ≦ 700 (3)
Y: Warpage of solar cell module (unit: μm)
X: product of the elastic modulus (unit: GPa) and thermal expansion coefficient (unit: ppm) of the insulating substrate.
According to the solar cell module of the present invention, the warpage Y (unit μm) of the solar cell module caused by heat during use or the like defines the material and thickness of the translucent substrate and the solar cell, and also the insulating substrate. By defining the ease of expansion / contraction defined by the product X of the elastic modulus E of 3 and the thermal expansion coefficient α as a parameter, the warpage Y of the solar cell module can be defined within the ranges of the above-described formulas. . Thereby, the curvature Y of a solar cell module can be suppressed so that failure does not occur, and reliability can be given.
The warpage of the solar cell module is ideally zero, but it is difficult in practice. For this reason, the upper and lower limits of the warpage according to the outer diameter of the solar cell module are set according to the formulas (1) and (2), and the materials of the translucent substrate and the solar cell are set within the range. The overall solar cell module is defined by defining the thickness and the ease of expansion / contraction by the product X of the elastic modulus and thermal expansion coefficient of the insulating substrate as parameters, and within the range of formulas (1) and (2). The warp Y can be reduced so that no failure occurs. At the same time, the upper limit of the warp Y that can maintain the reliability of the entire solar cell module and the upper limit of the product X, which is the ease of expansion and contraction of the insulating substrate, are defined by Equation (3).

In the solar cell module according to the present invention, it is preferable that the warp Y and the product X satisfy the following formula.
Y ≦ 500
X ≦ 300
By satisfying the above formula for the product X of the warpage Y of the solar cell module, the elastic modulus E of the insulating substrate 3 and the thermal expansion coefficient α, the insulating substrate is less likely to expand and contract, further reducing the warpage of the solar cell module. Can be made.

The thickness of the insulating substrate is preferably 20 μm or more and 3000 μm or less.
If the insulating substrate has a thickness in the above-mentioned range, since it is a thin layer, the heat of the solar battery cell in use or the like is transferred from one surface to the other surface, and the heat dissipation effect is high due to the temperature difference between the front and back surfaces. Warpage of the insulating substrate can be suppressed, and warpage of the solar cell module can be suppressed. On the other hand, when the film thickness of the insulating substrate is less than 20 μm, the handling property in the manufacturing process is lowered and it becomes difficult to handle, and by setting the upper limit of the film thickness to 300 μm, the above-described heat radiation effect of the cell can be sufficiently exhibited. Moreover, since the curvature by the temperature difference of front and back will increase gradually when it exceeds 3000 micrometers, it is at least 3000 micrometers or less, Preferably it is less than 3000 micrometers.
Therefore, the thickness of the insulating substrate is more preferably in the range of 20 μm to 300 μm.

The insulating substrate preferably has a structure in which glass fiber is impregnated with an insulating resin.
With this configuration, it is possible to improve the hardness of the insulating substrate and suppress warping of the entire solar cell module.

Moreover, the back sheet | seat is provided in the surface on the opposite side to the photovoltaic cell of an insulating substrate, and it is preferable that this back sheet | seat satisfies the following formula | equation.
X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (10)
If the above-described back sheet is provided, the insulating substrate can ensure a relatively easy expansion / contraction parameter, and the back sheet can further suppress the warpage of the solar cell module by suppressing the warping of the insulating substrate. .

Moreover, the back sheet | seat is provided in the surface on the opposite side to the photovoltaic cell of an insulating substrate, This back sheet | seat is characterized by satisfy | filling the following formula | equation.
0.9X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (11)
By making the ease of expansion and contraction of the back sheet 0.9 times or less than the ease of expansion and contraction of the insulating substrate, it is possible to improve the hardness of the back sheet and suppress expansion and contraction, and further suppress the overall warpage. .

Moreover, it is preferable that the photovoltaic cells arranged between the translucent substrate and the insulating substrate are arranged in a staggered manner.
Since the plurality of solar battery cells are arranged in a staggered manner, the stress that can occur in the gap between the cells can be dispersed in six directions. It can be made smaller than the stress generated in the gap between cells arranged in a grid in the prior art, and is less likely to cause wrinkles.

Moreover, it is preferable that a photovoltaic cell is a hexagon.
By forming a plurality of solar cells in a hexagonal shape and arranging them in a staggered manner, the stress that can occur in the gap between the cells can be dispersed in six directions, and the gap between the solar cells can be minimized. A large number of them can be installed to increase power generation efficiency.

  According to the solar cell module of the present invention, regarding the warpage of the solar cell module caused by heat, the material and thickness of the translucent substrate and the solar cell are regulated, and the product of the elastic modulus and the thermal expansion coefficient of the insulating substrate is used. By defining the ease of expansion / contraction defined as a parameter, the warpage of the solar cell module can be reduced within the range of the above-described formulas. Thereby, the curvature of a solar cell module can be suppressed and reliability can be given so that a failure may not occur.

It is a principal part cross-sectional schematic diagram of the solar cell module containing the insulating substrate by embodiment of this invention. It is a fragmentary top view which shows the shape and arrangement | sequence of a photovoltaic cell. It is a cross-sectional schematic diagram which shows the manufacturing process of the solar cell module shown in FIG. It is sectional drawing which simplified the longitudinal cross-section of the solar cell module in the shape of three layers in a pseudo manner. (A) is a figure which shows the curvature of a solar cell module with respect to the product of the elasticity modulus and thermal expansion coefficient of an insulation substrate according to the film thickness of an insulation substrate, (b) is the elasticity modulus and heat of an insulation substrate similarly to (a). It is a figure which shows the curvature of the solar cell module with respect to the product of an expansion coefficient and thickness. (A), (b), (c), (d) is the product of the elastic modulus and linear expansion coefficient of the insulating substrate and the warpage of each stacked three-layer system in each stacked three-layer system of solar cell modules having different outer diameters. It is a figure which shows the relationship. The solar cell module by a modification is shown, and it is a cross-sectional schematic diagram which provided the back sheet | seat on the back surface of the insulated substrate. It is a cross-sectional schematic diagram which shows an example of the conventional solar cell module.

A solar cell module according to an embodiment of the present invention will be described.
A solar cell module 1 according to this embodiment shown in FIG. 1 includes a translucent substrate 2 on which light such as sunlight is incident, an insulating substrate 3 disposed on the back side thereof, the translucent substrate 2 and the insulating substrate. 3 has a configuration in which a plurality of solar cells 5 arranged with a gap between them are roughly stacked. And between the translucent board | substrate 2 and the insulated substrate 3, the photovoltaic cell 5 is sealed with the sealing layer 6. FIG. The insulating substrate 3 constitutes an insulating base material.
The insulating substrate 3 is provided with a circuit layer 8 on one surface thereof, that is, the surface on the solar cell 5 side. A stud bump 10 is provided on an electrode portion of the circuit layer 8 that contacts the solar battery cell 5, and a non-electrode portion other than the electrode portion of the circuit layer 8 is covered with an overcoat layer 11.
The insulating substrate 3 is sealed by sandwiching the solar cells 5 with the sealing layer 6 and is joined and integrated with the translucent substrate 2 that becomes a light receiving surface, thereby forming the solar cell module 1.

Next, each member which comprises the solar cell module 1 is demonstrated.
In FIG. 1, examples of the translucent substrate 2 include silicon oxide such as a glass panel. Note that a transparent resin substrate such as an acrylic resin, a polycarbonate resin, or polyethylene terephthalate can also be used as the translucent substrate 2.
In addition, the circuit layer 8 provided on the solar cell 5 side of the insulating substrate 3 is a layer electrically connected to the solar cell 5. The circuit layer 8 has a pattern in which a large number of solar cells 5 arranged in a stack are electrically connected in series.
As a material constituting the circuit layer 8, a material having a low electric resistance, such as copper, aluminum, iron-nickel alloy, or the like is used. Moreover, a conductive polymer can also be used.
The surface of the circuit layer 8 is preferably roughened with a corrosive chemical such as formic acid, sulfuric acid, or nitric acid in order to improve adhesion between the stud bump 10 and the overcoat layer 11.

The stud bump 10 is a member that assists electrical connection between the circuit layer 8 and the solar battery cell 5, and is disposed corresponding to the electrode 5 a of the solar battery cell 5. The stud bump 10 in the present embodiment has a truncated cone shape, for example, and the tip protrudes from the surface of the overcoat layer 11.
A material having a low electrical resistance is used as the material of the stud bump 10. Among these, since the electrical resistance with the circuit layer 8 is lowered, it is preferable to contain one or more metals selected from the group consisting of silver, copper, tin, lead, nickel, and gold. In particular, the stud bump 10 is selected from the group consisting of silver, copper, tin, and solder (copper and lead are the main components) in order to easily form a desired shape such as a truncated cone with high viscosity. It is preferably formed of a conductive paste containing one or more metals.

The conductive paste is preferably a low temperature curing type. If the conductive paste is a low-temperature curing type, the electrode 5a of the solar battery cell 5 and the circuit layer 8 can be electrically connected by the stud bump 10 at a low temperature of 120 to 160 ° C. Since 120 to 160 ° C. is a temperature at which softening, melting, and crosslinking of the EVA film that can be used as the sealing film constituting the sealing layer 6 occurs, it is easy to use the EVA film as the sealing film. Therefore, the electrode 5a of the solar battery cell 5 and the stud bump 10 formed from the conductive paste can be more easily electrically connected.
Low-temperature curing type conductive paste contains a polymer and a conductive filler, and develops conductivity by physical contact of the conductive filler by curing the polymer. Coordinates and reduces silver or copper to organic matter The thing which contains a nanoparticle and expresses electroconductivity by carrying out low temperature sintering (120-160 degreeC) is mentioned. The latter material is preferable in that the electric resistance becomes lower.

The overcoat layer 11 is made of an insulating material. As an insulating material which comprises the overcoat layer 11, an epoxy resin, an acrylic resin, a urethane resin etc. are mentioned, for example. These resins may be used alone or in combination of two or more. In addition, the above resin may contain one or more inorganic powders selected from the group consisting of silica (SiO ₂ ), mica, alumina, and barium sulfate.
The overcoat layer 11 may be made of the same material as the sealing layer 6.

Next, the insulating substrate 3 will be described.
The insulating substrate 3 is made of a mesh-like glass fiber such as a single layer glass cloth. In this case, since the film thickness is thin, the heat of the solar battery cell 5 is transferred from one surface to the other surface, the heat dissipation effect is high, and the warping of the insulating substrate 3 due to the temperature difference between the front and back surfaces can be suppressed, and the drilling etc. Is easy to process. The insulating substrate 3 may be a composite material obtained by impregnating a mesh-like glass fiber with an insulating resin. In this case, it becomes harder than a single-layer glass cloth and becomes difficult to expand and contract.
As an example of a composite material in which a glass fiber is impregnated with an insulating resin, there is a prepreg made of a resin-containing fiber in which a mesh-like glass fiber is impregnated with a resin. Examples of the prepreg fibers include glass cloth, glass nonwoven fabric, and paper. The insulating resin is, for example, an epoxy resin, a polyimide resin, a bismaleimide triazine resin, an epoxy acrylate resin, or a urethane resin.
A prepreg is a form of a printed wiring board, and a finished product obtained by hardening a prepreg with heat is called a printed wiring board. FR-4, FR-5, BT materials, and the like are applied as finished prepregs obtained by impregnating glass fibers with an insulating resin.

  Here, when a glass panel such as quartz glass is used as the translucent substrate 2 in the solar cell module 1 and silicon oxide such as silicon is used as the solar cell 5, as shown in Table 1, the insulator substrate 3 is used. In the case of using a glass cloth such as a glass epoxy substrate rather than a conventional polymer film such as a PET film or a PEN film, a solar cell such as a translucent substrate 2 such as a glass panel or silicon is used. Since it is close to the cell 5, the warpage of the solar cell module 1 is small.

And the insulating substrate 3 is warped because the film thickness is formed in a thin layer so that the heat of the solar battery cell 5 is transferred to the barrier layer 4 side which is the back surface and the heat radiation effect is high and the temperature difference between the front and back surfaces is small. In addition, there is an advantage that processing such as drilling for the stud bump 10 or the like is easy.
Therefore, the thickness of the insulating substrate 3 is formed as a thin layer in the range of 20 μm to 300 μm. When the film thickness is less than 20 μm, handling in the production process is lowered and it becomes difficult to handle. On the other hand, an upper limit of 300 μm is a general upper limit for a single printed wiring board. Therefore, the upper limit of the insulating substrate 3 may exceed 300 μm, but if it exceeds 300 μm, the ease of expansion and contraction gradually increases. Further, the thickness of the insulating substrate 3 is preferably less than 3000 μm, and preferably at least 3000 μm or less in order to suppress the warpage of the solar cell module 1 to such an extent that it does not fail.

In addition, when the elastic modulus of the insulating substrate 3 is E (GPa) and the thermal expansion coefficient is α (ppm), the smaller the product of the elastic modulus E and the thermal expansion coefficient α, the harder the material becomes. Further, the warpage tends to increase as the thickness of the insulating substrate 3 increases.
Since the insulating base material constituting the insulating substrate 3 is made of a single layer glass cloth or impregnated with an insulating resin, it has high heat resistance, high insulating properties, high electrical reliability, and flexibility and flexibility. Therefore, it has the characteristic that it is easy to carry and store etc. by winding on a roll in the material stage before lamination, so-called roll-to-roll. Therefore, handling becomes easy without taking up space.

Next, the solar battery cell 5 will be described. The solar battery cell 5 is of a back contact type having, for example, a plus electrode and a minus electrode on the back surface. The solar battery cell 5 is preferably made of silicon. For example, a single crystal silicon type, a polycrystalline silicon type or the like is used. Among these, the single crystal silicon type is preferable in terms of excellent power generation efficiency. The thickness of the solar battery cell 5 is in the range of 100 μm to 300 μm.
For example, as shown in FIGS. 2A and 2B, the solar battery cell 5 is formed in a square plate shape or a hexagonal plate shape, and a gap G is formed between the translucent substrate 2 and the insulating substrate 3. Open and arranged in a staggered pattern. Although the plurality of solar cells 5 are arranged separately from each other, the translucent substrate 2 and the insulating substrate 3 are constituted by a single plate, and therefore stress such as wrinkles is formed in the gap G between the solar cells 5 and 5. There is a problem that concentrates. On the other hand, this stress can be disperse | distributed to six directions by arranging the photovoltaic cell 5 in zigzag form. In particular, by forming the solar cell 5 in a hexagonal shape, preferably a regular hexagonal plate shape, the gap G between the cells 5 and 5 is minimized, and the occupied area of the cell 5 with respect to the entire area of the solar cell module 1 is increased. Power generation efficiency can be improved.

  The sealing layer 6 is formed of a sealing film. As the sealing film, for example, an EVA film, an ethylene / (meth) acrylic acid ester copolymer film, a fluororesin film such as polyvinylidene fluoride, or the like is used. Usually, the film for sealing is used by two or more sheets so that the photovoltaic cell 5 may be pinched | interposed.

Next, the structure which suppresses the curvature by the solar cell module 1 which has the above-mentioned structure is demonstrated.
In the solar cell module 1, as described above, silicon oxide such as a glass panel having a thickness of 2 mm to 4 mm is used as the translucent substrate 2, and a crystalline solar cell having a thickness of 100 μm to 300 μm is used as the solar cell 5. A battery cell shall be used. When the thickness of the translucent substrate 2 is less than 2 mm, or when the thickness of the solar battery cell 5 is less than 100 μm, the strength of the solar battery module 1 is remarkably lowered, and there is a risk of breakage. Moreover, when the thickness of the translucent board | substrate 2 exceeds 4 mm or when the thickness of the photovoltaic cell 5 exceeds 300 micrometers, the weight and cost of the solar cell module 1 jump and it is unpreferable practically.

The warpage Y (unit: μm) of the solar cell module 1 due to heat can be defined by the following equation using the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3 as a parameter.
Y ≦ 12.88X + 521.7 (1)
Y ≧ 0.0324X + 83.69 (2)
Y ≦ 1000
X ≦ 700 (3)
If the warpage of the solar cell module 1 is 1000 μm or less, reliability as a product can be ensured.
It is more preferable that the warpage Y of the solar cell module 1 and the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3 satisfy the following expression.
Y ≦ 500
X ≦ 300 (4)

Here, the warp of the solar cell module 1 is ideally 0 even when it receives heat, but it is difficult in practice. Therefore, the upper limit and the lower limit of the warp Y corresponding to the usable outer diameter size of the solar cell module 1 are set by a linear expression based on the method of least squares according to the expressions (1) and (2), and are within the range. The material and thickness of the translucent substrate 2 and the solar battery cell 5 are defined, and the ease of expansion / contraction due to the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3 is used as a parameter.
The warpage Y of the entire solar cell module 1 can be reduced to the extent that no failure occurs by defining it within the range of the expressions (1) and (2). At the same time, in relation to the expressions (1) and (2), the upper limit of the warp Y that can maintain the reliability of the entire solar cell module and the upper limit of the ease X of expansion and contraction of the insulating substrate 3 are expressed by the expression (3). Stipulated by.
Further, in order to further reduce the warp Y of the solar cell module 1 to a more preferable range, it is preferable that the warp Y and the ease X of expansion / contraction are within the range of the formula (4).

Next, the manufacturing method of the solar cell module 1 according to the present embodiment will be described with reference to FIG.
First, for example, a glass epoxy resin is applied as an insulating material constituting the insulating substrate 3 to one surface of a sheet-like PET film as a support. Then, for example, copper Cu is deposited as a conductive layer for patterning for forming the circuit layer 8 on the surface of the insulating substrate 3 opposite to the PET film.
In this way, a laminate in which the conductive layer (circuit layer 8) and the glass epoxy resin (insulating substrate 3) are laminated is obtained.
Next, the insulating resin made of glass epoxy resin or the like becomes the insulating substrate 3 by heat-treating the laminate. Here, as the conductive layer, metal foil such as aluminum or iron-nickel alloy can be used in addition to copper. Moreover, the layer containing a conductive polymer may be sufficient.
Next, the circuit layer 8 is formed by etching the conductive layer using a resist pattern. In the formation of the circuit layer 8, the circuit layer 8 is obtained by patterning the conductive layer by applying photolithography.

Next, an overcoat layer 11 is formed by applying an insulating overcoat material to the non-electrode portion of the circuit layer 8.
Next, stud bumps 10 are formed on the electrode portions of the circuit layer 8. As a method for forming the stud bump 10, for example, methods such as plating, screen printing, dispensing, and transfer can be applied. In that case, since it can be made into a desired shape easily, it is preferable to use the electrically conductive paste containing 1 or more types of metals chosen from the group which consists of silver, copper, tin, and solder. Furthermore, a low temperature curing type conductive paste is more preferable in that the electrode 5a of the solar battery cell 5 and the stud bump 10 can be more easily electrically connected.

Next, the sealing film 6 </ b> A, the solar battery cell 5, the sealing film 6 </ b> B, and the translucent substrate 2 are sequentially laminated on the overcoat layer 11 of the insulating substrate 3. In that case, it arrange | positions so that the stud bump 10 may oppose the electrode 5a of the photovoltaic cell 5. FIG.
Subsequently, the laminated body of the insulating substrate 3, the sealing film 6A, the solar battery cell 5, the sealing film 6B, and the translucent substrate 2 is heated and pressurized. By this heating and pressing, the stud bump 10 is penetrated through the sealing film 6A and brought into contact with the electrode 5a of the solar battery cell 5, and further, the tip end of the stud bump 10 is crushed to ensure a sufficient connection area.
In this way, the insulating substrate 3, the sealing film 6 </ b> A, the solar battery cell 5, the sealing film 6 </ b> B, and the translucent substrate 2 are brought into close contact, and at the same time, the solar battery cell 5 is electrically connected in series with the circuit layer 8. The solar cell module 1 shown in FIG. 1 is obtained.

As described above, the solar cell module 1 according to the present embodiment has the following operational effects.
a) In the solar cell module 1 according to the present embodiment, the warp Y (unit: μm) of the solar cell module 1 due to heat defines the material and thickness of the translucent substrate 2 and the solar cell 5, and further the insulating substrate. 3 can be defined by the formulas (1) and (2), with the ease of expansion / contraction defined by the product X of the elastic modulus E of 3 and the thermal expansion coefficient α as a parameter. It can be suppressed by the ease of expansion and contraction, which is a physical property value of 3.
b) Since the insulating substrate 3 is a single-layer glass cloth made of a glass-like glass epoxy resin or a glass cloth impregnated with an insulating resin, a PET film or a PEN film conventionally used as an insulating resin is used. Compared to a polymer film such as the above, the linear expansion coefficient is close to that of the light-transmitting substrate 2 such as a glass panel and the solar battery cell 5 such as silicon, so that the warpage of the solar cell module 1 is reduced.
c) Further, since the insulating substrate 3 is formed in a thin layer in the range of 20 μm to 300 μm or 20 μm to 3000 μm, the heat of the solar cell 5 is transferred from the front side to the back side, and the heat radiation effect is high. Since the temperature difference is small, it is difficult to warp and machining such as drilling for the stud bump 10 is easy.
d) Further, since the solar cells 5 arranged between the translucent substrate 2 and the insulating substrate 3 have a plurality of solar cells 5 arranged in a staggered manner, they are generated in the gap G between the cells 5 and 5. The obtained stress can be dispersed in six directions. Moreover, by forming the solar battery cells 5 in a hexagonal shape, the gap G between the cells 5 can be minimized and the power generation efficiency can be improved.

Next, the solar cell module 1 according to the present embodiment shown in FIG. 1 is configured as a three-layer laminated system in which the translucent substrate 2, the solar cell 5, and the insulating substrate 3 are combined. The warpage was measured to define its characteristics. Then, Test Examples 1 and 2 which are grounds for deriving the above formulas (1) to (4) were performed.
First, quartz glass was used as the translucent substrate 2, and the thickness was set in the range of 2 mm to 4 mm. As an example, the thickness of the translucent substrate 2 was 3.3 mm.
A silicon chip was used as the solar battery cell 5 and the thickness was set in the range of 100 μm to 300 μm.

A glass epoxy substrate was used as the insulating substrate 3 and the film thickness was set in the range of 20 μm to 300 μm. In Example 1, the thickness of the insulating substrate 3 was two types of 100 μm and 200 μm.
As Comparative Example 1 and Comparative Example 2 of the insulating substrate 3, PET and PEN were used.
The elastic modulus E and the linear expansion coefficient α in Examples, Comparative Examples 1 and 2 of the insulating substrate 3 were as shown in Table 1.
And about the solar cell module 1 which consists of a three-layer laminated system, Example 1, the comparative example 1, and the comparative example 2 are each used as the insulating substrate 3, and the translucent board | substrate 2 and the photovoltaic cell 5 are Example 1, and a comparative example. Samples were manufactured using the same configurations of 1 and 2, respectively. The film thicknesses of Example 1, Comparative Example 1, and Comparative Example 2 of the insulating substrate 3 were 100 μm and 200 μm, respectively. The solar cell module 1 that is a three-layer laminated system including the insulating substrate 3 according to the first embodiment, the first comparative example, and the second comparative example is also referred to as the first embodiment, the first comparative example, and the second comparative example. They were formed with the same dimensions.

[Test Example 1]
In Test Example 1, the size of the optical substrate 2 in Example 1 and Comparative Examples 1 and 2 was 4 × 4 inches (10 cm × 10 cm) in outer diameter. The solar cells 5 in Example 1 and Comparative Examples 1 and 2 were 100 mm long × 100 mm wide × 200 μm thick.
Further, the dimensions of the insulating substrate (including glass epoxy resin, PET, PEN) are the same as the translucent substrate 2, and the outer diameter is 4 × 4 inches (10 cm × 10 cm), and the thickness is 100 μm and 200 μm. did. As Reference Examples 1 to 6, those obtained by doubling or halving one or both of the elastic modulus E and the thermal expansion coefficient α of the conventional PEN film used for the insulating substrate were also used. As test conditions, the temperature difference between the front and back surfaces of each solar cell module 1 in Examples, Comparative Examples 1 and 2 and Reference Examples 1 to 6 is set to 100 ° C., and each solar cell module 1 is formed every 100 μm and 200 μm in thickness of each insulating substrate 3. The warpage of was measured.
In addition, the curvature of the solar cell module 1 was measured by the distance to the edge part of the direction orthogonal to the radial direction of the solar cell module 1 with respect to the center position.
The results are shown in Table 2.

The data of the results shown in Table 2 are shown in the graphs of FIGS. 5A, for Example 1, Comparative Example 1, and Comparative Example 2, the horizontal axis represents each elastic modulus × thermal expansion coefficient of the insulating substrate 3 (including glass epoxy resin, PET, and PEN), and the vertical axis. The warp (μm) of the solar cell module 1 was taken and plotted for every 100 μm and 200 μm thickness of the insulating substrate 3.
In FIG. 5A, when the insulating resin 3 has a film thickness of 100 μm, the plots can be combined into the following equation (5) by connecting the plots with a least-squares line that is a linear equation by the least-squares method.
Y = 0.214X + 127.1 (5)
However, Y: Warpage of the solar cell module 1 X: Product of the elastic modulus E of the insulating resin 3 and the thermal expansion coefficient α Further, when the insulating resin 3 has a film thickness of 200 μm, each plot is connected by a straight line as follows: 6).
Y = 0.428X + 127.1 (6)

Further, in FIG. 5B, the horizontal axis represents the thickness of the elastic modulus × thermal expansion coefficient × insulating substrate (glass epoxy resin, PET, PEN), and the vertical axis represents the warpage (μm) of the solar cell module 1. Then, the warpage of the solar cell module 1 when the thickness of the insulating substrate is 100 μm and 200 μm is plotted. By taking the elastic modulus × thermal expansion coefficient × thickness of the insulating substrate on the horizontal axis, the warpage of the solar cell module 1 can be summarized into the following linear expression regardless of the thickness of the insulating substrate.
Y = 2.14X + 127.1 (7)

[Test Example 2]
Next, Test Example 2 will be described.
In Test Example 2, glass epoxy resin is used for the insulating substrate 3 as Example 2, and the outer diameter of the solar cell module 1 is 5 × 5 inch, 6 × 6 inch, 8 × 8 inch, 12 × 12 inch disk. The light-transmitting substrate 2 and the insulating substrate 3 made of quartz glass have the same dimensions. The thickness of the translucent substrate 2 was as described in Table 1, and the thickness of the insulating substrate 3 was two types of 25 μm and 3000 μm. The dimensions of the solar battery cell 5 using silicon were the same as those in Test Example 1. As Reference Examples 7, 8, and 9, those obtained by halving one or both of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3 were used.
The dimensions of the solar cell 5 in Test Example 2 are 200 μm in thickness in both Example 2 and Reference Examples 7, 8, and 9, and the outer diameter dimensions are 120 mm × 120 mm, 150 mm × 150 mm, 200 mm × 200 mm, 300 mm ×. Four types of 300 mm were used.
As test conditions, the temperature difference between the front and back surfaces of each solar cell module 1 in Example 2 and Reference Examples 7, 8, and 9 was set to 100 ° C. And the curvature of each solar cell module 1 was measured according to thickness 25 micrometers and 3000 micrometers for every outer-diameter dimension of each insulated substrate 3. FIG.
The results are shown in Table 3.

The data of the results shown in Table 3 are shown in the graphs of FIGS. 6A, 6 </ b> B, 6 </ b> C, and 6 </ b> D for each outer diameter dimension of the solar cell module 1. In each graph, the horizontal axis is the elastic modulus E × thermal expansion coefficient α of the insulating substrate 3, the vertical axis is the warp of the solar cell module 1, and the warp size is plotted for each thickness of 25 μm and 3000 μm of the insulating substrate 3. .
When the thickness of the insulating substrate 3 is 3000 μm, the value of the warp Y is greatly different between the case where only the elastic modulus E is ½ and the case where only the thermal expansion coefficient α is ½ (Table 3, FIG. ) To (d)). When the thickness of the insulating substrate 3 is equivalent to that of the translucent substrate 2, the elastic modulus E × thermal expansion coefficient α of the insulating substrate 3 is not a good parameter. Therefore, as in Test Example 1, a least square line was entered in each figure. When the elastic modulus E of the insulating substrate 3 approaches 0, the thicknesses of 25 μm and 3000 μm should approximate the same warp value. Therefore, the least square line of the thickness of 3000 μm was changed as follows.
That is, first, a least square line having a thickness of 25 μm is drawn, and its y-axis intercept is obtained. Then, the least square line passing through the y-axis intercept of a straight line having a thickness of 3000 μm and a thickness of 25 μm was obtained.

According to the above-described procedure, for Example 2 and Reference Examples 7, 8, and 9, when plotting and drawing a straight line for each thickness 25 μm and 3000 μm of the insulating substrate 3, the primary shown in FIGS. 5 (a) to 5 (d). It can be put together in a formula.
In the solar cell module 1 having the smallest outer diameter of 5 inches, the absolute amount of warping is the smallest, and in particular, the smallest insulating substrate 3 having a thickness of 25 μm can be summarized by the following linear expression (8).
Y = 0.0324X + 83.69 (8)
In the solar cell module 1 having the largest outer diameter of 12 inches, the absolute amount of warping is the largest. In particular, the largest insulating substrate 3 having a thickness of 3000 μm can be summarized by the following linear expression (9).
Y = 12.88X + 521.7 (9)

Therefore, the solar cell module 1 having the above-described outer diameter size range is expressed by the above formulas (8) and (9) in relation to the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3. The range of the warp Y can be defined so that the warp Y is contained within. This can be shown by the following formulas (1) and (2).

Y ≦ 12.88X + 521.7 (1)
Y ≧ 0.0324X + 83.69 (2)
Here, if the warpage of the solar cell module 1 is 1000 μm at the maximum (Y ≦ 1000 μm), the reliability of the solar cell module 1 can be secured. More preferably, it is 700 μm or less (Y ≦ 700 μm). In addition, the product X of the elastic modulus E and the thermal expansion coefficient α in the insulating substrate 3 is 700 or less considering numerical values of epoxy resin, polyimide resin, bismaleidotriazine resin, etc., which are insulating resins impregnated in the glass cloth. (X ≦ 700 μm). Preferably, it is 300 or less (X ≦ 300 μm).

Next, a modified example of the present invention will be described.
In the solar cell module 13 according to the modification of the present embodiment, the back sheet for reinforcing the hardness of the solar cell module 1 on the back surface of the insulating substrate 3, that is, the surface opposite to the solar cell 5, to further reduce the warpage. May be provided.
A solar cell module 13 shown in FIG. 7 has the configuration of the solar cell module 1 shown in FIG. 1, and a back sheet 14 is attached to the back surface of the insulating substrate 3.
In this case, the relationship between the insulating substrate 3 and the back sheet 14 is defined by the following equation (10). That is, the product of the elastic modulus E × thermal expansion coefficient α of the insulating substrate 3 is a parameter X, and
X ≧ elastic modulus F of the backsheet 14 × thermal expansion coefficient β (10)
The back sheet 14 is made harder than the insulating substrate 3 and is attached to the insulating substrate 3 so that the sheet portion of the solar cell module 1 including the insulating substrate 3 is not stretched or contracted. Can be suppressed.

The above equation (10) requires that the product X of the elastic modulus E × thermal expansion coefficient α of the insulating substrate 3 is equal to or greater than the elastic modulus F × thermal expansion coefficient β of the backsheet 14. What is necessary is just to satisfy following Formula (11).
0.9 × X ≧ elastic modulus F × thermal expansion coefficient β of the backsheet 14 (11)
Thereby, the curvature suppression effect of the solar cell module 13 can further be improved rather than the solar cell module 1 by the above-mentioned embodiment.

In FIG. 7, a barrier layer may be provided as the back sheet 14.
The barrier layer is a layer that is provided on the back surface of the insulating substrate 3 and adjusts air permeation. For example, a polyvinyl fluoride resin (PVF) film (trade name “Tedlar” having weather resistance such as water vapor barrier property and oxygen barrier property and a little insulating property is provided. "; Registered trademark) is used.
Alternatively, as the barrier layer, another resin film having the same characteristics as the vinyl fluoride resin may be used. That is, a ceramic vapor-deposited film (“GL film”; trade name of Toppan Printing Co., Ltd.) having a structure in which a high-barrier alumina oxide (or silica) is provided as a gas barrier layer on one side of a polyester film (or polyamide film). May be used.
Moreover, you may use a gas-barrier laminated | multilayer film ("GX film"; the brand name by Toppan Printing Co., Ltd.) as a barrier layer. The gas barrier laminate film is disclosed in detail in Japanese Patent No. 4013604. A PET film may be deposited and laminated on the surface of the barrier layer opposite to the insulating substrate 3, and scratch resistance is improved by laminating the PET film.

Note that the present invention is not limited to the above-described embodiments, and appropriate configurations and materials can be changed without departing from the gist of the present invention, and these are also included in the present invention.
Further, in the above-described embodiment and the like, the insulating substrate 3 has the stud bump 10 and the overcoat layer 11, but these are optional. However, it is preferable to have the stud bump 10 in that the solar cell module 1 can be more easily manufactured. Moreover, it is preferable to have the overcoat layer 11 in that the short circuit between the circuit layers 8 adjacent to each other can be prevented and the corrosion of the circuit layer 8 by the acetic acid gas released from the EVA film can be prevented.

1 Solar cell module 2 Translucent substrate
3 Insulating substrate 5 Solar cell 6 Sealing layer 8 Circuit layer 9 Barrier layer 10 Stud bump 11 Overcoat layer

Claims (8)

A solar cell module having a translucent substrate, a solar cell, and an insulating substrate including electrical wiring,
The translucent substrate is made of silicon oxide having a thickness of 2 mm or more and 4 mm or less,
The solar cell is composed of a crystalline solar cell having a thickness of 100 μm or more and 300 μm or less,
The solar cell module characterized by the physical property value of each member being prescribed | regulated by the following formula | equation.
Y ≦ 12.88X + 521.7 (1)
Y ≧ 0.0324X + 83.69 (2)
Y ≦ 1000
X ≦ 700 (3)
Y: Warpage of solar cell module
X: product of elastic modulus and thermal expansion coefficient of insulating substrate 2. The solar cell module according to claim 1, wherein Y and X satisfy the following expression.
Y ≦ 500
X ≦ 300 (4)     3. The solar cell module according to claim 1, wherein the insulating substrate has a thickness of 20 μm to 3000 μm.     The solar cell module according to any one of claims 1 to 3, wherein the insulating substrate has a structure impregnated with an insulating resin of glass fiber. The solar cell according to any one of claims 1 to 4, wherein a back sheet is provided on a surface of the insulating substrate opposite to the solar battery cell, and the back sheet satisfies the following expression. Battery module.
X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (10) The solar cell according to any one of claims 1 to 5, wherein a back sheet is provided on a surface of the insulating substrate opposite to the solar battery cell, and the back sheet satisfies the following expression. Battery module.
0.9X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (11)     The solar cell module according to claim 1, wherein the solar cells are arranged in a staggered pattern. The solar cell module according to any one of claims 1 to 7, wherein the solar cell has a hexagonal shape.

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