JP2011216779A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module that can suppress poor electrical connection between backside contact solar cells and can easily mount the solar cells without restriction of material selection of an insulating base material.SOLUTION: A solar cell module 1 has a translucent plate 2, a plurality of solar cells 5, electrical wirings 8 connecting the solar cells, and an insulating substrate 3. The plurality of cells 5 is sealed by a sealing layer 6 between the plate 2 and the insulating substrate 3. The translucent plate 2 is a glass panel having a thickness of 2-4 mm. For the solar cells 5, crystalline solar cells having thicknesses of 100 μm or more and 300 μm or less are used. The solar cell module 1 satisfies formula (1), Y≤12.88X+521.7, formula (2), Y≥0.0324X+83.69, and formula (3), Y≤1,000, X≤700, assuming that Y denotes a warpage (unit: μm) of the solar cell module 1, X denotes a product of a modulus of elasticity E (unit: GPa) of the insulating substrate 3, and a thermal expansion coefficient α (unit: ppm).

Description

  The present invention relates to a solar cell module in which a back electrode type back electrode type solar cell having an electrode on the back surface is sealed.

  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, and a translucent substrate 120. And a large number of solar cells 130 sealed between the back sheets 110. The solar battery cell 130 is sandwiched and sealed between sealing films 140 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 a light receiving surface of the sun and a positive electrode (P-type semiconductor electrode) 132 on the back surface side, The wiring material 150 overlapped on the light receiving surface of the solar battery cell 130, and the area efficiency of photoelectric conversion tended to decrease.

  Furthermore, 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 the difference in the coefficient of thermal expansion of each member. It was.

  In order to solve these problems, for example, 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. The back electrode type solar cells in the solar cell module of this system are connected to each other by a circuit of an insulating base disposed on the back side of the back electrode type solar cells.

  That is, this solar cell module has a structure in which a circuit layer is laminated on the surface of an insulating substrate, and a back electrode type solar cell is further laminated on the circuit layer. For this reason, the light receiving area on the surface of the back electrode type solar battery cell is not sacrificed, and the reduction in the area efficiency of photoelectric conversion can be prevented. Furthermore, since it is not necessary to have a structure in which the wiring material wraps from the front side to the back side, there is an advantage that disconnection of the wiring material due to a 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, a circuit layer as a wiring material is formed on the surface of the insulating substrate, and a back electrode type solar cell is laminated on the circuit layer. Therefore, when exposed to high temperature during use of the solar cell module, the back electrode type solar cell is caused by the difference in linear expansion coefficient between the insulating substrate, the circuit layer and the back electrode type solar cell. There was a possibility of peeling from the insulating substrate.

  That is, since the insulating base material has a higher linear expansion coefficient than the back electrode type solar cell and the translucent base material, the insulating base material is higher than the back electrode type solar cell and the translucent base material at high temperatures. The expansion difference has led to the cause of the back electrode type solar cell peeling off from the insulating base material.

  Furthermore, since the back electrode type solar cell is directly mounted on the insulating base material on which the circuit layer is formed, the insulating base material is required to have a mounting process resistance, and the material selection of the insulating base material is restricted. I had received it. Moreover, since the back electrode type solar cell is configured as a huge pair chip, it is technically difficult to mount the back electrode type solar cell itself, and it has not been easy to manufacture.

  The present invention has been made in view of such a problem, and it is possible to suppress peeling of each member and suppress poor electrical connection between back electrode type solar cells, and a material for an insulating substrate. It aims at providing the solar cell module which can mount a back electrode type photovoltaic cell easily, without receiving the restriction | limiting of selection.

In order to solve the above problems, the present invention proposes the following means.
That is, the solar cell module according to the present invention includes an insulating base, a plurality of back electrode solar cells arranged side by side on the surface side of the insulating base, and back electrodes of the back electrode solar cells. Electrical wiring connected in the same plane, and a sealing resin that is laminated on the surface of the insulating base material and seals the back electrode type solar cells and the electrical wiring in a separated state with respect to the insulating base material, A translucent base material laminated on the surface of the sealing resin, the translucent base material made of silicon oxide having a thickness of 2 mm or more and 4 mm or less, and the back electrode type solar cell having a thickness of 100 μm. It consists of a crystalline back electrode type solar cell of 300 μm or less and satisfies the following formulas (1), (2) and (3).
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

  According to the solar cell module of the present invention, the materials and thicknesses of the translucent substrate and the back electrode type solar cell are specified for the warp Y (unit: μm) of the solar cell module caused by heat during use. At the same time, the warpage Y of the solar cell module is defined within the range of the above-mentioned formulas by defining, as a parameter, the ease of expansion and contraction defined by the product X of the elastic modulus and the thermal expansion coefficient of the insulating substrate. Can do. Thereby, the curvature Y of a solar cell module can be suppressed so that failure does not occur, and reliability can be given.

  In addition, although it is ideal that the curvature of a solar cell module is 0, it is difficult in reality. Therefore, the translucent base material and the back electrode type solar cell are set so that the upper and lower limits of the warp according to the outer diameter size of the solar cell module are set by the formulas (1) and (2) and fall within the range. In addition to defining the material and thickness of the cell, use the product X of the elastic modulus and thermal expansion coefficient of the insulating base as a parameter, and specify it within the range of formulas (1) and (2). Thus, the warpage Y of the entire solar cell module can be reduced so as not to cause a failure. 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 base material, were defined by Equation (3).

  Also, the electrical wiring and back electrode type solar cells are not directly mounted on the insulating base material, but these electrical wirings and back electrode type solar cells are encapsulated in a sealing layer laminated on the insulating base material. Since the structure is sealed, the insulating base material is not required to have mounting process resistance, and the material selection range of the insulating base material can be widened. Furthermore, since the electric wiring and the back electrode type solar cell can be fixed and integrated on the insulating base material only by sealing the electric wiring and the back electrode type solar cell on the insulating base material, the manufacturing process can be simplified. Can do.

In the solar cell module according to the present invention, it is preferable that the warp Y and the product X satisfy the following expression (4).
Y ≦ 500, X ≦ 300 (4)
By satisfying the above formula for the product X of the warpage of the solar cell module and the elastic modulus and thermal expansion coefficient of the insulating base material, the insulating base material is less likely to expand and contract, and the warpage of the solar cell module is further reduced. Can do.

Furthermore, the film thickness of the insulating base material is preferably 20 μm or more and less than 3000 μm.
If the insulating substrate has a thickness in this range, since it is a thin layer, the heat of the back electrode type solar cell during use etc. is transferred from one surface to the other surface, and the heat dissipation effect is high. Warpage of the insulating base material due to a temperature difference can be suppressed, and warpage of the solar cell module can be suppressed.
On the other hand, when the film thickness of the insulating base material is less than 20 μm, the handling property in the manufacturing process is lowered and it becomes difficult to handle. Moreover, the curvature by the temperature difference of front and back will increase gradually that it is 3000 micrometers or more. Therefore, the film thickness of the insulating base material is most preferably in the range of 20 μm to 300 μm.

The insulating base material preferably has a structure in which an insulating resin is impregnated into glass fiber.
With this configuration, the hardness of the insulating base material can be improved and the warpage of the entire solar cell module can be suppressed.

Moreover, it is preferable that the back sheet is laminated | stacked on the back surface side of the said insulating base material, and this back sheet satisfy | fills following (5) Formula.
X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (5)
If such a back sheet is provided, the insulating base material can be relatively easily expanded and contracted, and the warping of the solar cell module can be further suppressed by suppressing the warping of the insulating base material by the back sheet. be able to.

Moreover, it is more preferable that the said back sheet satisfy | fills following (6) Formula.
0.9X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (6)
By making the ease of expansion and contraction of the back sheet 0.9 times or less of the ease of expansion and contraction of the insulating base material, the hardness of the back sheet is improved and the expansion and contraction is suppressed, and the overall warpage is further suppressed. it can.

Furthermore, it is preferable that the said back surface electrode type photovoltaic cell is arranged in zigzag form by planar view.
Since the plurality of back electrode type solar cells are arranged in a staggered manner, the stress that can occur in the gap between the cells can be dispersed in six directions. As a result, the stress generated in the gap between the cells can be further reduced as compared with the conventional arrangement in the form of a lattice, and wrinkles and the like are less likely to occur.

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

According to the solar cell module according to the present invention, for the warpage of the solar cell module caused by heat, the material and thickness of the translucent substrate and the back electrode type solar cell are specified, and the elastic modulus of the insulating substrate and By defining the ease of expansion / contraction defined by the product of the thermal expansion coefficients as a parameter, the warpage of the solar cell module can be reduced within the ranges 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.
Moreover, without mounting the back electrode type solar battery cell on the insulating base material, the back electrode is sealed with the sealing layer in a state where the back electrodes are connected to each other by the electric wiring, thereby improving the mounting yield and the solar cell module. In addition to improving the reliability of the insulating base material, it is not necessary to consider the mounting process resistance of the insulating base material.

It is a principal part cross-sectional schematic diagram of the solar cell module of embodiment of this invention. It is a fragmentary top view which shows the shape and arrangement | sequence of a back electrode type 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 shows the state which simplified the longitudinal cross-section of the solar cell module in the shape of three layers pseudo | simulated. 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 insulating base material. (A) is the figure which shows the curvature of the solar cell module with respect to the product of the elasticity modulus and thermal expansion coefficient of an insulation base material according to the film thickness of an insulation base material, (b) is the elasticity of an insulation base material like (a). It is a figure which shows the curvature of the solar cell module with respect to the product of a rate, a thermal expansion coefficient, and thickness. (A), (b), (c), (d) is the product of the elastic modulus and linear expansion coefficient of the insulating base material in each laminated three-layer system of solar cell modules having different outer diameters, and each laminated three-layer system. It is a figure which shows the relationship with curvature. It is a cross-sectional schematic diagram which shows an example of the conventional solar cell module.

Hereinafter, a solar cell module according to an embodiment of the present invention will be described in detail with reference to the drawings.
A solar cell module 1 according to the present 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, and a translucent substrate 2. And the schematic structure which laminated | stacked the several back-electrode-type solar cell 5 arranged with the clearance gap between the insulating base materials 3 is comprised.

  In the present embodiment, the back electrode type solar battery cells 5 are electrically connected to each other back electrode 5a by the electric wiring 8 through the conductive adhesive 10, and the back electrode type solar battery cells 5 and The electrical wiring 8 is sealed between the translucent substrate 2 and the insulating substrate 3 by the sealing layer 6. These sealing layers 6 are joined to and integrated with the translucent substrate 2 whose back side is joined to the insulating base 3 and whose front side is light-receiving noodles, whereby the solar cell module 1 is formed.

  In addition, the said electric wiring 8 is arrange | positioned so that the back surface electrode type photovoltaic cell 5 may be connected on the same plane as shown in FIG. 1, Furthermore, these back surface electrode type photovoltaic cells 5 and electric wiring 8 is sealed by the sealing layer 6 in a separated state with respect to the surface of the insulating substrate 3.

Next, each member which comprises the solar cell module 1 is demonstrated.
In FIG. 1, as the translucent substrate 2, for example, silicon oxide such as a glass panel is used. In addition, as this translucent base material 2, it is also possible to use transparent resin base materials, such as an acrylic resin, a polycarbonate resin, and a polyethylene terephthalate.

  The electrical wiring 8 is a wiring for electrically connecting the back electrode type solar cells 5. The electrical wiring 8 electrically connects a number of back electrode type solar cells 5 arranged in a stacked manner in series. In particular, in this embodiment, as described above, the back side of the back electrode type solar cells 5 Are arranged on the same plane. As a material constituting the electric wiring 8, a material having a low electric resistance, such as copper, aluminum, iron-nickel alloy, or the like is used.

The conductive adhesive 10 is a member that assists electrical connection between the electrical wiring 8 and the back electrode type solar battery cell 5, and is disposed corresponding to the back electrode 5 a of the back electrode type solar battery cell 5. .
A material having a low electrical resistance is used as the material of the conductive adhesive 10. Among these, since the electric resistance with the electric wiring 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 conductive adhesive 10 is formed of a conductive paste containing one or more metals selected from the group consisting of silver, copper, tin, and solder (copper and lead are the main components). Is preferred.

  The conductive adhesive 10 is preferably a low temperature curing type. If the conductive adhesive 10 is a low temperature curing type, the back electrode 5a of the back electrode type solar cell 5 and the electrical wiring 8 can be electrically connected 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 back electrode 5a of the back electrode type solar battery cell 5 and the conductive adhesive 10 can be more easily electrically connected.

  Low-temperature curing type conductive adhesives include polymers and conductive fillers that develop conductivity through the physical contact of the conductive fillers by curing the polymer. Coordinate and reduce silver or copper to organic substances. In addition, a material that exhibits electrical conductivity by low-temperature sintering (120 to 160 ° C.) is included. The latter material is preferable in that the electric resistance becomes lower.

Next, the insulating base material 3 will be described.
The insulating substrate 3 is made of, for example, a reticulated glass fiber such as a polymer film such as PET or PEN, or a single layer glass cloth. In this case, since the film thickness is thin, the heat of the back electrode type solar battery cell 5 is transmitted 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. Processing such as drilling is easy. 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, a prepreg made of a resin-containing fiber in which a mesh-like glass fiber is impregnated with a resin is known. 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.
The prepreg is one form of a printed wiring board, and a finished product obtained by hardening the 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 back electrode type solar cell 5, as shown in Table 1, insulation is performed. The substrate 3 is made of a glass cloth such as a glass epoxy substrate rather than a conventionally used polymer film such as a PET film or a PEN film. Since the solar cell module 1 is close to the back electrode type solar cell 5 such as silicon or silicon, the warpage of the solar cell module 1 is small.

  And since the insulating base material 3 forms the film thickness in a thin layer, the heat of the back electrode type solar cell 5 is transmitted to the back surface side, and the heat dissipation effect is high, and the temperature difference between the front and back surfaces is small. There is an advantage that warpage is less likely to occur. Therefore, in the solar cell module 1 of this embodiment, the film thickness of the insulating base material 3 was comprised in the thin layer of the range of 20 micrometers-300 micrometers. 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, the upper limit of 300 μm is a general upper limit for a single printed wiring board. Therefore, the upper limit of the insulating base 3 may exceed 300 μm, but if it exceeds 300 μm, the ease of expansion and contraction gradually increases. In addition, the thickness of the insulating base material 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.

Further, when the elastic modulus of the insulating base material 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 and the material is less likely to expand and contract. . Further, the warpage tends to increase as the thickness of the insulating base 3 increases.
The insulating base material that constitutes the insulating base material 3 is a single-layer glass cloth or a structure in which an insulating resin is impregnated with this, so that it has high heat resistance, high insulation properties, high electrical reliability, and flexibility. And flexible. Therefore, it has the characteristic of being easy to carry and store by being wound on a roll at the material stage before lamination, that is, so-called roll-to-roll, and can be easily handled without taking up space.

  Next, the back electrode type solar cell 5 will be described. The back electrode type solar battery cell 5 is of a back contact type having both a plus electrode and a minus electrode on the back surface. The back electrode type solar 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 back electrode type solar cell 5 is in the range of 100 μm to 300 μm.

  The back electrode type solar cell 5 is formed in a square plate shape or a hexagonal plate shape as shown in FIGS. 2A and 2B, for example, and between the translucent substrate 2 and the insulating substrate 3. Are arranged in a tetragonal or zigzag manner with gaps G between them. The plurality of back electrode type solar cells 5 are arranged separately from each other, but the translucent base material 2 and the insulating base material 3 are constituted by a single plate. There is a problem that stresses such as wrinkles are concentrated in the gap G. On the other hand, this stress can be disperse | distributed to six directions by arranging the back surface electrode type photovoltaic cell 5 in zigzag form. In particular, by forming the back electrode type 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 reduced. The power generation efficiency can be improved by increasing the power generation efficiency.

  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.

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 thickness of 100 μm to 300 μm is used as the back electrode type solar cell 5. A crystalline back electrode type solar battery cell is used. When the thickness of the translucent substrate 2 is less than 2 mm, or when the thickness of the back electrode type solar battery cell 5 is less than 100 μm, the strength of the solar cell module 1 is remarkably lowered, and there is a risk of breakage. Moreover, when the thickness of the translucent base material 2 exceeds 4 mm, or when the thickness of the back electrode type solar battery cell 5 exceeds 300 μm, the weight and cost of the solar battery module 1 jump up, which is not practically preferable.

The warp 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 base 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 base material 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. In addition to defining the material and thickness of the translucent substrate 2 and the back electrode type solar cell 5, the ease of expansion / contraction by the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating substrate 3 is a parameter. It was.

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 equations (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 easiness of expansion and contraction X of the insulating base material 3 (3) It was defined by the formula.
Moreover, in order to reduce the curvature Y of the solar cell module 1 to a more preferable range, it is preferable that the curvature 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, a commercially available prepreg material in which a glass fiber is impregnated with an epoxy resin is heated and cured to obtain the insulating base material 3.

  Next, the back electrode 5 a of the back electrode type solar cell 5 and the electrical wiring 8 are connected using the conductive adhesive 10. As a method for applying the conductive adhesive 10, for example, methods such as 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 conductive adhesive containing 1 or more types of metals chosen from the group which consists of silver, copper, tin, and solder. Furthermore, the surface of the electrode 5a is cleaned with acid, alkali, ultraviolet light, plasma, etc. in that the back electrode 5a of the back electrode type solar battery cell 5 and the conductive adhesive 10 can be more easily electrically connected. It is desirable to improve the wettability of the conductive adhesive 10.

  Next, the sealing film 6 </ b> A, the back electrode type solar cell 5, the sealing film 6 </ b> B, and the translucent substrate 2 are sequentially laminated on the insulating base 3 in this order from the back side to the front side. Then, a heat and pressure treatment is performed on the laminated body of the insulating base material 3, the sealing film 6 </ b> A, the back electrode type solar battery cell 5, the sealing film 6 </ b> B, and the translucent base material 2.

  Thereby, the back electrode type solar cell is sealed in the sealing layer 6 by bringing the insulating base material 3, the sealing film 6 </ b> A, the back electrode type solar battery cell 5, the sealing film 6 </ b> B, and the translucent base material 2 into close contact. The solar cell module 1 shown in FIG. 1 in which the battery cell 5 and the electric wiring 8 are sealed is obtained. In this solar cell module 1, the back electrode type solar cells 5 and the electric wiring 8 are completely sealed in the sealing layer 6 without being in contact with the insulating base material 3. All 8 are arranged on the same plane.

According to such a solar cell module 1 of this embodiment, there exist the following effects.
a) In the solar cell module 1 according to the present embodiment, the warpage Y (unit: μm) of the solar cell module 1 due to heat defines the material and thickness of the translucent substrate 2 and the back electrode type solar cell 5. Furthermore, since the ease of expansion and contraction defined by the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating base 3 can be defined as a parameter, the formula (1) and the formula (2) can be used to define the solar cell module 1. The warp Y can be suppressed by the ease of expansion and contraction, which is a physical property value of the insulating base 3.

b) Moreover, since the single-layer glass cloth which consists of a mesh-like glass epoxy resin or what impregnated this glass cloth with the insulation resin was used as the insulation base material 3, PET film and PEN which were conventionally used as the insulation resin Compared with a polymer film such as a film, the linear expansion coefficient is close to that of a translucent substrate 2 such as a glass panel or a back electrode type solar cell 5 such as silicon, so that the warpage of the solar cell module 1 is reduced. .

c) Moreover, since the insulating base material 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 back electrode solar cell 5 is transferred from the front surface side to the back surface side, and the heat dissipation effect Is high and the temperature difference between the front and back surfaces is small, so warpage is unlikely to occur, and drilling for the stud bump 10 and the like is easy.

d) Furthermore, since the back electrode type solar cells 5 arranged between the translucent substrate 2 and the insulating substrate 3 have a plurality of back electrode type solar cells 5 arranged in a staggered pattern, the cells 5 The stress that can occur in the gap G between the cells 5 can be dispersed in six directions. Moreover, by forming the back electrode type solar cell 5 in a hexagonal shape, the gap G between the cell 5 and the cell 5 can be minimized and the power generation efficiency can be improved.

e) Further, the back electrode type solar cells 5 and the insulating base material 3 are not directly connected, and the individual back electrode type solar cells 5 are connected by the electric wiring 8 arranged on the same plane. Therefore, the degree of freedom of installation of the back electrode type solar battery cell 5 is increased, and the installation position accuracy can be relaxed. Thereby, the manufacturing yield of a back electrode type photovoltaic cell improves.

f) Further, since the electrical wiring 8 and the back electrode type solar battery cell 5 are not directly mounted on the insulating base material 3, the insulating base material 3 is not required to have mounting process resistance, and the insulation The range of material selection for the substrate 3 can be expanded. Moreover, since these can be fixed on the insulating base material 3 only by sealing the electric wiring 8 and the back electrode type solar cell 5 with the sealing layer 6 on the insulating base material 3, the manufacturing process is simplified. Can be achieved.

As mentioned above, although embodiment of this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.
For example, as a modification, the solar cell module 11 having the configuration shown in FIG. 5 may be used. In this modified example, the back sheet for reinforcing the hardness of the solar cell module 11 on the back surface side of the insulating substrate 3, that is, the surface opposite to the back electrode type solar cell 5 to further reduce the warpage. 9 is provided.

The solar cell module 11 of this modification has a structure in which a back sheet 9 is attached to the back surface of the insulating base 3 in addition to the configuration of the solar cell module 1 of the embodiment. In this case, the relationship between the insulating base material 3 and the back sheet 9 is defined by the following equation (5) with the product of the elastic modulus E × thermal expansion coefficient α of the insulating base material 3 as a parameter X.
X ≧ (elastic modulus F × thermal expansion coefficient β of backsheet 9) (5)

  That is, by making the back sheet 9 harder than the insulating base material 3 and attaching the back sheet 9 to the insulating base material 3, the sheet portion of the solar cell module 1 including the insulating base material 3 is not stretched or shrunk. And the curvature of the whole solar cell module 11 can be suppressed.

In addition, in the above-mentioned formula (5), it is a requirement that the product X of the elastic modulus E × thermal expansion coefficient α of the insulating base 3 is equal to or greater than the elastic modulus F × thermal expansion coefficient β of the backsheet 9, The back sheet 9 only needs to satisfy at least the following formula (6).
0.9 × X ≧ the elastic modulus F of the backsheet 14 × the thermal expansion coefficient β (6)
Thereby, the curvature suppression effect of the solar cell module 11 can further be improved rather than the solar cell module 1 by the above-mentioned embodiment.

  In FIG. 5, it is preferable to provide a barrier layer as the back sheet 9. This barrier layer is a layer that is provided on the back surface of the insulating base 3 and adjusts air permeation. For example, a vinyl fluoride resin (PVF) film having a weather resistance such as a water vapor barrier property and an oxygen barrier property and a little insulating property (trade name) "Tedlar" (registered trademark) is used.

  Moreover, you may use the other resin film which has the characteristic similar to a vinyl fluoride resin as this other barrier layer. 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.

  Further, a gas barrier laminate film (“GX film”; trade name manufactured by Toppan Printing Co., Ltd.) may be used as the 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 the scratch resistance can be improved by laminating the PET film.

  Next, the solar cell module 1 of the embodiment shown in FIG. 1 is approximated as a three-layer laminated system in which the translucent substrate 2, the back electrode type solar cells 5 and the insulating substrate 3 are combined (see FIG. 4). ), The physical properties of each component were specified, and the overall warpage was measured to define its characteristics. Then, Test Examples 1 and 2 serving as a basis for deriving the above equations (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. Moreover, a silicon chip was used as the back electrode type solar 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 base material 3 was two types of 100 μm and 200 μm.
As Comparative Example 1 and Comparative Example 2 of the insulating base material 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 base material 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 base material 3, and the translucent base material 2 and the back electrode type photovoltaic cell 5 are implemented. Samples were manufactured using Examples 1 and Comparative Examples 1 and 2 having the same configuration. 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 laminate system including the insulating substrate 3 according to Example 1, Comparative Example 1, and Comparative Example 2 is also referred to as Example 1, Comparative Example 1, and Comparative Example 2, and each member. 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 an outer diameter of 4 × 4 inches (10 cm × 10 cm). The back electrode type solar cells 5 in Example 1 and Comparative Examples 1 and 2 were 100 mm long × 100 mm wide × 200 μm thick.
The dimensions of the insulating base (including glass epoxy resin, PET, PEN) are 4 × 4 inches (10 cm × 10 cm) in outer diameter as in the case of the translucent base 2 and the thicknesses are 2 μm, 100 μm and 200 μm. Kind. 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 base material 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 100 ° C., and each solar cell module has a thickness of 100 μm and 200 μm. A warp of 1 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. 6 (a) and 6 (b). 6A, for Example 1, Comparative Example 1, and Comparative Example 2, the horizontal axis represents each elastic modulus × thermal expansion coefficient of the insulating base material 3 (including glass epoxy resin, PET, and PEN), and the vertical axis The warp (μm) of the solar cell module 1 was taken on the axis and plotted for every 100 μm and 200 μm in thickness of the insulating substrate 3.
In FIG. 6A, when the insulating resin 3 has a film thickness of 100 μm, the plots can be combined into the following equation (6) by connecting each plot with a least-squares line that is a linear equation by the least-squares method.
Y = 0.214X + 127.1 (7)
However, Y: Warpage of solar cell module 1 X: Product of elastic modulus E and thermal expansion coefficient α of insulating resin 3 When the thickness of insulating resin 3 is 200 μm, when each plot is connected by a straight line, the following formula ( 8).
Y = 0.428X + 127.1 (8)

In FIG. 6B, the horizontal axis represents the thickness of the insulating base material (glass epoxy resin, PET, PEN) × elastic coefficient × thermal expansion coefficient ×, and the vertical axis represents the warpage (μm) of the solar cell module 1. And 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 base material 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 base material.
Y = 2.14X + 127.1 (9)

[Test Example 2]
Next, Test Example 2 will be described.
In Test Example 2, glass epoxy resin is used for the insulating base material 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 circle. The translucent base material 2 and the insulating base material 3 made of a plate type and 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 back electrode type solar 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 base material 3 were used.

The dimensions of the back electrode type 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 × 300 mm.
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 insulation base material 3. FIG.
The results are shown in Table 3.

  Data of the results shown in Table 3 are shown in the graphs of FIGS. 7A, 7 </ b> B, 7 </ b> C, and 7 </ 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 base material 3, and the vertical axis is the warpage of the solar cell module 1, and the warpage size is 25 μm and 3000 μm in thickness of the insulating base material 3. Plotted.

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 times and the case where only the thermal expansion coefficient α is ½ times (Table 3, FIG. a) to (d)). When the thickness of the insulating base material 3 is equivalent to that of the translucent base material 2, the elastic modulus E × thermal expansion coefficient α of the insulating base material 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, so 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, Example 2 and Reference Examples 7, 8, and 9 are plotted for each thickness 25 μm and 3000 μm of the insulating base 3 and drawn straight lines, as shown in FIGS. It can be summarized into a linear expression.
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, in the insulating base material 3 having the smallest thickness of 25 μm, the following linear expression (10) can be obtained.
Y = 0.0324X + 83.69 (10)
In the solar cell module 1 having the largest outer diameter of 12 inches, the absolute amount of warping is the largest, and in particular, the largest insulating substrate 3 having a thickness of 3000 μm can be summarized by the following linear expression (11).
Y = 12.88X + 521.7 (11)

Therefore, the solar cell module 1 having the above-mentioned outer diameter size range is expressed by the above formulas (10) and (11) in relation to the product X of the elastic modulus E and the thermal expansion coefficient α of the insulating base 3. The range of the warp Y can be defined so that the warp Y falls within the range. 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 base 3 is 700 in consideration of numerical values such as an epoxy resin, a polyimide resin, a bismaleidotriazine resin, etc., which are insulating resins impregnated in the glass cloth. It is necessary to make the following (X ≦ 700 μm). Preferably, it is 300 or less (X ≦ 300 μm).

1 Solar cell module 2 Translucent substrate
3 Insulating substrate 5 Back electrode type solar cell 5a Back electrode 6 Sealing layer 8 Electrical wiring 9 Back sheet (barrier layer)
10 conductive adhesive 11 solar cell module

Claims (8)

An insulating substrate;
A plurality of back electrode type solar cells arranged side by side on the surface side of the insulating substrate;
Electrical wiring for connecting the back electrodes of each of the back electrode type solar cells in substantially the same plane,
A sealing resin that is laminated on the surface of the insulating base material and seals the back electrode solar cell and the electrical wiring in a separated state with respect to the insulating base material;
A translucent base material laminated on the surface of the sealing resin,
The translucent substrate is made of silicon oxide having a thickness of 2 mm or more and 4 mm or less,
The back electrode type solar cell is composed of a crystalline back electrode type solar cell having a thickness of 100 μm or more and 300 μm or less,
A solar cell module satisfying the following formulas (1), (2) and (3):
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 The solar cell module according to claim 1, wherein the following expression (4) is satisfied.
Y ≦ 500, X ≦ 300 (4)   The film thickness of the said insulation base material is 20 micrometers or more and 3000 micrometers or less, The solar cell module of Claim 1 or 2 characterized by the above-mentioned.   The solar cell module according to any one of claims 1 to 3, wherein the insulating base material has a structure impregnated with an insulating resin of glass fiber. 5. The solar cell module according to claim 1, wherein a back sheet is laminated on a back surface side of the insulating base material, and the back sheet satisfies the following expression (5).
X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (5) The solar cell module according to claim 5, wherein the back sheet satisfies the following expression (6).
0.9X ≧ (elastic modulus of back sheet × thermal expansion coefficient of back sheet) (6)   The solar cell module according to any one of claims 1 to 6, wherein the back electrode type solar cells are arranged in a staggered manner in a plan view.   The solar cell module according to claim 7, wherein the back electrode type solar cell has a hexagonal shape in plan view.

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