JP2018190748A - Manufacturing method of solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relatively thick wiring material at a repaired portion when a repaired portion is present in a solar cell string. In this case, in the manufacturing process of the solar cell module, the pressure at the time of thermocompression bonding concentrates on the portion where the thickness of the wiring material is thick, and there is a possibility that the solar cell string may be re-damaged. A step of laminating a surface-side protective material 60, a surface-side filler 40, a repaired solar cell string 100rp, a back-side filler 50, and a back-side protective material 70 in this order and thermocompression bonding. A buffer sheet 81 having a melting point lower than that of the backside filler 50 is further laminated between the repaired solar cell string 100rp and the backside filler 50. This is a method for manufacturing the solar cell module 800 for thermocompression bonding. [Selection] Figure 7

Description

  The present invention relates to a method for manufacturing a solar cell module.

  Solar cells are expected as a new energy source because they can directly convert clean and infinitely supplied solar energy into electrical energy.

  In general, the output per solar cell is about several watts and is brittle. Therefore, when a solar cell is used as a power source for a house or a building, the output is increased by electrically connecting a plurality of solar cells, and the solar cells are protected from impact by using glass or resin filler. A solar cell module configured to protect is used.

  Currently, ethylene vinyl acetate copolymer (EVA) and polyolefins are widely used as fillers used in solar cell modules. These are soft sheets in a non-crosslinked state, and have a sufficient hardness and form a transparent protective layer by crosslinking by thermocompression bonding in the manufacturing process of the solar cell module. The material used as the filler is selected based on various indicators such as the fluidity in the thermocompression bonding process, the hardness and the expansion / contraction rate after the thermocompression bonding.

  On the other hand, when forming a solar cell string by electrically connecting a plurality of solar cells to form a solar cell module, the solar cells may be partially damaged before and after the connection work. It is common to connect a plurality of solar cells using wiring materials to form a solar cell string. However, since solar cells are expensive parts, one of them is damaged or cracked after completion. If found, it is more economical to replace only broken cells. Therefore, the following techniques have already been disclosed.

JP2011-159646A

  The wiring material that has already been electrically connected is cut to remove the solar cells, and the new solar cells are connected using another wiring material. Large unevenness occurs compared to other regions, such as overlapping. At this time, there was a problem that the solar battery cell easily breaks in the portion at the time of thermocompression bonding for sealing the solar battery. In particular, this phenomenon may occur when protrusions generated in the solar cell string repair portion or the like come into contact with a relatively hard material even before the heat crosslinking.

  The present invention has been made in view of such a situation, and it is possible to manufacture a solar cell module without lowering the yield even when a protrusion such as a repair portion is present on the solar cell string. The purpose is to be able to.

A method for manufacturing a solar cell module comprising a step of laminating a surface side protective material, a surface side filler, a solar cell string, a back surface side filler, and a back surface side protective material in this order and thermocompression bonding. Further, a buffer sheet having a melting point lower than that of the back surface side filler is further laminated between the solar cell string and the back surface side filler, and the method for manufacturing the solar cell module is performed by thermocompression bonding.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing yield of a solar cell module can be improved.

It is sectional drawing of the conventional solar cell module 900. FIG. 5 is a cross-sectional view showing a method for laminating each member when manufacturing a solar cell module 900. FIG. 1 is a top view of a solar battery cell 10. FIG. 4 is a back view showing a state in which some cells of solar cell string 100 are damaged. FIG. (A) It is sectional drawing of the repaired solar cell string 100rp, (b) It is a back view of 100rp. It is sectional drawing which shows the lamination | stacking method of each member in the solar cell module 600 which concerns on 1st Embodiment. It is sectional drawing which shows the lamination | stacking method of each member in the solar cell module 700 which concerns on 2nd Embodiment. It is a partial back view of the solar cell module 800 in 3rd Embodiment.

Embodiments according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.
(Configuration of solar cell module)

  First, the general structure of a general solar cell module 900 will be described. FIG. 1 is a cross-sectional view of a conventional solar cell module 900. The solar cell module 900 includes a solar cell string 100 formed by electrically connecting a plurality of solar cells 10 using the wiring material 30, a surface-side protective material 60 formed of a plate material such as glass or acrylic resin, and the solar cell string 100. Is a laminated body in which a front surface side filler 40 and a back surface side filler 50 and a back surface side protective material 70 made of a plate material such as glass or acrylic resin, or a resin sheet are laminated and heat-pressed.

  For the surface side protective material 60, a glass plate, acrylic resin, or the like having high light transmittance is used. A resin sheet having sufficient light transmittance and flexibility is used for the surface side filler 40, and ethylene / vinyl acetate copolymer (EVA) and polyolefin are widely used at present. A resin sheet having flexibility is used for the back surface side filler 50, and EVA and polyolefin are widely used at present. A glass plate, an acrylic resin plate, a resin sheet or the like is used for the back surface side protective material 70. Here, the front-side filler 40 and the back-side filler 50 may be the same material or a combination of different materials.

Here, the “surface” refers to a surface of the solar cell module 900 on which sunlight is mainly incident. Since sunlight does not directly enter from the back surface side of the solar cell module 900, the back surface side filler 50 and the back surface side protection material 70 among the materials constituting the solar cell module 900 do not need to have light transmittance. Further, the back-side filler 50 and the back-side protective material 70 are made white by dispersing light diffusing particles and the like for diffusing sunlight incident from the surface of the solar cell module 900 and re-entering the solar cell 10. It may be used.

FIG. 2 is a cross-sectional view showing a method of laminating each member when manufacturing the solar cell module 900. In the manufacturing process of the solar cell module 900, after sequentially laminating each material so that the laminate as described above is configured, the front side filler 40 and the back side filler 50 are bonded by thermocompression bonding, Both the fillers are cross-linked to seal the solar cell string 100. At the same time, the front surface side filler 40 and the front surface side protective material 60, and the back surface side filler 50 and the back surface side protective material 70 are bonded. Thus, the solar cell module 900 having the cross-sectional structure shown in FIG. 1 is formed. Next, the configuration of the solar battery cell 10 and the assembly of the solar battery string 100 will be described.
(Configuration of solar cell string)

  First, a schematic configuration of the solar battery cell 10 will be described. The solar cell 10 includes a crystalline semiconductor substrate provided with a photoelectric conversion region, and a protruding electrode for collecting carriers and holes generated in the photoelectric conversion region. Specifically, 1) a semiconductor junction region is formed on a crystalline semiconductor substrate made of silicon or the like by a diffusion method, an evaporation method, or the like, and 2) a protective film or a transparent conductive oxide made of silicon nitride or the like on the semiconductor junction region. A photoelectric conversion element is formed by forming a transparent conductive oxide film made of Then, the photovoltaic cell 10 is formed on the photoelectric conversion element by forming the protruding electrode 20 using 3) a resin paste containing conductive metal powder or the like. Note that the structure of the photoelectric conversion region is not limited to this, and may be a silicon heterojunction (SHJ) structure in which an amorphous silicon layer containing a dopant is stacked over a crystalline semiconductor substrate.

  The protruding electrode 20 includes at least a bus bar electrode portion to which the wiring member 30 is connected when the plurality of solar cells 10 are connected. In addition to this, a finger electrode portion that is orthogonal to the bus bar electrode portion and formed narrower than the bus bar electrode portion may be provided. Next, a method for forming the solar cell string 100 by connecting the solar cells 10 will be described.

  FIG. 3 is a top view of the solar battery cell 10. The back side of the solar battery cell 10 has the same configuration. As the wiring member 30 used for connecting the solar cells 10, a material in which a core material made of copper is coated with silver or solder is used. In the two adjacent solar cells 10, the protruding electrode 20 a on the front surface side of the first solar cell 10 and the protruding electrode 20 b on the back surface side of the second solar cell 10 are combined into one wiring member 30. By connecting by, the 1st photovoltaic cell 10 and the 2nd photovoltaic cell 10 can be connected in series. The operation is repeated until a predetermined number of solar cells 10 are connected, and the solar cell string 100 is formed.

The means for connecting the solar cells 10 is not particularly limited. For example, the wiring member 30 in which the periphery of the core wire made of copper is coated with solder may be used for connection by soldering. As another example, the wiring member 30 in which the periphery of the core wire made of copper is covered with a metal such as silver may be connected by a conductive double-sided tape made of a resin containing conductive particles.
(Solar cell string repair)

  FIG. 4 is a back view showing a state in which some cells in the solar cell string 100 are damaged. When the solar cell string 100 is formed as described above, or after the solar cell string 100 is formed, only a part of the plural solar cells 10 that are connected due to an impact during connection work, thermal stress of soldering, or the like. In addition, cracks, cracks, and cracks may occur. Since the solar battery cell 10 is an expensive part, it is economically disadvantageous to discard the entire solar battery string 100. Therefore, only the damaged solar battery cell 10br is replaced with a new solar battery cell 11.

  At this time, in the solar battery string 100, the wiring member 30 connected to the damaged solar battery cell 10br is cut with scissors or the like to remove the solar battery cell 10br, and the new solar battery cell 11 that is not damaged Replace. The wiring member 30 is additionally arranged at a portion where the new solar battery cell 11 is connected, and the solar battery string 100 is repaired by connecting the wiring material 30 to obtain a repaired solar battery string 100rp.

  Fig.5 (a) is sectional drawing of the repaired solar cell string 100rp, and FIG.5 (b) is a back view of 100rp. In this figure, the solar battery cell 10 and the new solar battery cell 11 are connected using the wiring member 30 on the back surface side. In the connection part of the photovoltaic cells 10 and 11, the wiring material 30 partially overlaps and the whole thickness as the wiring material 30 is thick.

The wiring members 30 are not necessarily completely overlapped, and may be slightly shifted. Furthermore, in the repaired portion, soldering is performed in order to connect the wiring members 30 to each other, and a conductive tape is additionally disposed, so that the appearance is deteriorated. Therefore, it is preferable to perform repair by adjusting the position so that the connection portion between the wiring members 30 rotates to the back side of the solar cells 10 and 11. In the following description, it is assumed that the repaired portion of the repaired solar cell string 100rp is on the back side of the solar cells 10 and 11.
(First embodiment)

  In the repaired portion of the repaired solar cell string 100rp, the wiring members 30 partially overlap each other, and the thickness of the wiring member 30 increases only in the repaired portion. The portion where the thickness of the wiring member 30 is thick is called a convex portion for convenience. When the convex portion is the largest, the height is a protrusion having a height that is equivalent to the two wiring members 30 overlapped. When such a repaired solar cell string 100rp is sealed with the front surface side filler 40 and the back surface side filler 50, when pressure is applied in the thermocompression bonding step, the pressure concentrates on the convex portion, and the repaired solar cell The battery string 100rp may be damaged again.

  Therefore, when sealing such a repaired solar cell string 100rp, the back surface side filling which contacts the surface which has a convex part among the repaired solar cell string 100rp, ie, the back surface side of the photovoltaic cells 10 and 11, is carried out. What is necessary is just to arrange | position the material which reduces an impact between the material 50 and the photovoltaic cell 10 and 11. FIG. For example, a material having a melting point lower than that of the back-side filler 50 is preferably used as the material for reducing the impact. This material having a melting point lower than that of the back-side filler 50 is referred to herein as a “buffer sheet”.

  In the thermocompression bonding step, the buffer sheet 80 is disposed so as to be in contact with the convex portion, so that the buffer sheet 80 reaches the melting point before the back surface side filler 50 and softens, and the convex portion is formed on the softened buffer sheet 80. Sinks. The buffer sheet 80 softened prior to the back-side filler 50 serves as a cushion material, and can suppress pressure concentration on the convex portion. Although the thickness of a buffer sheet is not specifically limited, The effect as a buffer sheet will increase if the thing thicker than the maximum height of a convex part is used. Specifically, the thickness is preferably about 200 to 600 μm.

FIG. 6 is a cross-sectional view showing a method for laminating each member in the solar cell module 600 according to the first embodiment. In the first embodiment, the buffer sheet 80 is of a size having substantially the same area as the area of the light receiving surface of the solar cell module 600. The buffer sheet 80 covers the entire back surface side of the repaired solar cell string 100rp, including the convex portion of the repaired solar cell string 100rp.
(effect)

In the thermocompression bonding step in the solar cell module forming step, it is possible to prevent re-damage of the repaired solar cell string 100rp due to the pressure applied during the thermocompression bonding step being concentrated on the convex portion of the repaired solar cell string 100rp. Thereby, the yield at the time of manufacturing the solar cell module is improved.
(Second Embodiment)

  FIG. 7 is a cross-sectional view showing a method for laminating each member in the solar cell module 700 according to the second embodiment. In the second embodiment, the buffer sheet 81 is arranged only in a necessary place. When the buffer sheet 80 having a large area as described in the first embodiment is used, re-breakage of the repaired solar cell string 100rp can be prevented, but the increase in manufacturing cost is large. Therefore, the buffer sheet 81 having a small area is arranged only in a portion that contacts the convex portion where the re-damage of the repaired solar cell string 100rp is particularly concerned.

  The size of the buffer sheet 81 is not particularly limited as long as it can cover the convex portion, but as shown in FIG. 7, in the repaired solar cell string 100rp, there is one solar cell to be repaired. Since the connection part of the wiring material 30 arises in cross-sectional view whenever it does, it is preferable that it is the magnitude | size which can cover the convex part of the two places simultaneously. In the second embodiment, the buffer sheet 81 has a size of 150 mm square, for example.

  Even in the second embodiment, since the buffer sheet 81 is in contact with the convex portion of the repaired solar cell string 100rp, pressure concentration on the convex portion can be avoided as in the first embodiment. The yield of the solar cell module is improved. That is, according to the second embodiment, it is possible to minimize an increase in manufacturing cost while improving the yield of the solar cell module. (Third embodiment)

  FIG. 8 is a partial back view of a solar cell module 800 according to the third embodiment. In the third embodiment, a buffer sheet 82 is provided between the thick wiring material and the solar cell string 100 at the position where the thick wiring material is placed on the solar cell in the solar cell module 800. Deploy.

  In the solar cell module, wiring for connecting the solar cells 10 such as the inter-string wiring member 32 for connecting the solar cell strings 100 and the power extracting wiring member 33 for extracting power from the solar cell string 100. A wiring material different from the material is used. As shown in FIG. 8, these wiring members are often arranged so as to overlap the solar cell string 100 at a position that cannot be seen from the surface of the solar cell module, that is, on the back surface side of the solar cell 10.

  The inter-string wiring member 32 and the power extraction wiring member 33 are insulated from the solar cell string 100 by an insulating sheet (not shown) made of, for example, PET and having a thickness of about 50 μm. Since the sheet made of PET is hard and thin, when thermocompression bonding is performed to seal the solar cell string 100 in this state, the inter-string wiring member 32 and the power extraction wiring member 33 are connected to the solar cell via the insulating sheet. The solar cell 10 may be pressed and pressed in the direction of the cell 10 to be damaged.

  In order to prevent the solar cell 10 from being damaged, it is preferable to provide a buffer sheet 82 between the inter-string wiring member 32 and the power extraction wiring member 33 and the solar cell string 100. The positional relationship between the insulating sheet and the buffer sheet 82 is not particularly limited. The solar cell string 100 and the buffer sheet 82 may be in contact with each other, or the solar cell string 100 may be disposed in contact with the insulating sheet, and then the buffer sheet 82 may be disposed.

  In such a configuration, when heating is started, the buffer sheet 82 is first softened, and the inter-string wiring member 32 and the power extraction wiring member 33 are pressed against the softened buffer sheet 82, so that the solar cell 10 is obtained. Such pressure is relieved. After that, the back surface side filler 50 and the front surface side filler 40 are softened and crosslinked to seal the solar cell string 100 and the like. In order to enhance the effect, the thickness of the buffer sheet 82 is preferably about 200 to 600 μm.

  By disposing the buffer sheet 82 in such a position, the solar battery cell 10 can be prevented from cracking around the inter-string wiring member 32 and the power extraction wiring member 33. In addition, although 3rd Embodiment may be implemented separately from 2nd Embodiment, it cannot be overemphasized that the manufacturing yield of the solar cell module 800 becomes still higher by performing together.

  In the first to third embodiments, the relationship between the melting point of the back surface side filler 50 and the melting point of the buffer sheet 80 or 81, 82 has been described. The relationship with the melting point of is preferably as follows.

  Melting point of backside filler> Melting point of front side filler> Melting point of buffer sheet

  By configuring in this way, there is an advantage in the thermocompression bonding process of the solar cell module 800. In the thermocompression bonding step, the front surface side protective material 60 is disposed at the bottom, and the front surface side filler 40, the solar cell string 100 or the repaired solar cell string 100rp, the back surface side filler 50, and the back surface side protective material 70 are disposed thereon. Are stacked in this order. Prior to the back surface side filler 50, the surface side filler 40 having a low melting point is softened first, so that the solar cell string 100 or the repaired solar cell string 100rp is bonded to the surface side filler 40 first, The back surface side filler 50 can be covered on top. If it does in this way, position shift of solar cell string 100 or repaired solar cell string 100rp in a thermocompression bonding process will be eased.

  In addition to this, it is preferable to use a resin having a thermal expansion coefficient between the front surface side filler 40 and the back surface side filler 50 as follows.

    Thermal expansion coefficient after cross-linking of front side filler> Thermal expansion coefficient after heating of back side filler

  As described above, in the configuration of the solar cell module 800, the front side protection member 60 made of a light-transmitting plate made of a glass plate, an acrylic plate or the like is used on the light incident side, and the back side protection made of a resin sheet on the back side. The material 70 is often used. When the solar cell module 800 is used, each member constituting the solar cell module 800 expands and contracts due to a change in temperature of the day, seasonal variations, and the like. At this time, the thin and flexible back side protective material 70 made of a resin sheet or the like is more easily expanded and contracted than the front side protective material 60 made of a hard material such as a glass plate or an acrylic plate. In such a case, expansion / contraction of the back surface side protective material 70 is achieved by reducing the thermal expansion coefficient of the back surface side filler material 50 that contacts the back surface side protective material 70 out of the front surface side filler 40 and the back surface side filler 50. However, it does not affect the back surface side filler 50 and can prevent the stretching stress from reaching the sealed solar battery cell 10. Thereby, the displacement of the solar battery cell 10 and the tensile stress and bending stress applied to the wiring member 30 are alleviated, and the reliability of the solar battery module 800 can be improved.

The present invention has been described above based on the embodiments. However, the present invention is not limited to this, and can be modified without departing from the spirit of the present invention. For example, in the present application, the example in which the buffer sheet is disposed in the portion where the protrusion is generated in the repair portion of the solar cell string or the location where the power extraction wiring material having a thickness larger than that of the wiring material is used is described. Needless to say, even when protrusions other than those described here occur, such as the unevenness of the solder when forming the battery string, the buffer sheet can be disposed at that location.

  10, 10br, 11: Solar cell, 100: Solar cell string, 100rp: Repaired solar cell string, 30: Wiring material, 32: Wiring material between strings, 33: Wiring material for extracting power, 40: Surface side filler 50: Back side filler, 60: Front side protective material, 70: Back side protective material, 80, 81, 82: Buffer sheet

Claims (5)

A surface side protective material;
A surface-side filler;
A solar cell string,
A back side filler,
A back side protective material;
A solar cell module manufacturing method including a step of laminating in this order and thermocompression bonding,
A method for manufacturing a solar cell module, wherein a buffer sheet having a melting point lower than that of the back surface side filler is further laminated between the solar cell string and the back surface side filler, and the thermocompression bonding is performed. It is a manufacturing method of the solar cell module according to claim 1,
A method for manufacturing a solar cell module, comprising: stacking the buffer sheet at least one of a repair portion of a solar cell string, an arrangement position of an inter-string wiring material or a power extraction wiring material. It is a manufacturing method of the solar cell module according to claim 1 or 2,
The method for manufacturing a solar cell module, wherein the buffer sheet has a melting point lower than the melting point of the back surface side filler and not more than the melting point of the front surface side filler. It is a manufacturing method of the solar cell module according to claim 3,
The method for manufacturing a solar cell module, wherein a melting point of the front surface side filler is lower than a melting point of the back side filler, and is equal to or higher than a melting point of the buffer sheet. It is a manufacturing method of the solar cell module according to any one of claims 1 to 4,
The back surface side protective material is a sheet containing a resin,
The method for manufacturing a solar cell module, wherein the back surface side filler is made of a material having a thermal expansion coefficient after heat-crosslinking lower than that after heat cross-linking of the surface side filler.

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