JP2006278740A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a convex portion comes up at a connection tab or soldered location, in the solar cell module wherein an area between a translucent substrate and a backside material is sealed with a filler and solar cell elements are allocated, the filler on the optical receiving surface side of the gap between a protrusion of the connection tab and the translucent substrate, and the gap between a protrusion built up by soldering and the translucent substrate, gets thinner, which could cause deterioration in the electrical insulation performance of the solar cell module. <P>SOLUTION: For the fillers attached on the optical receiving surface side and/or those attached on the backside of the solar cell module, the configuration is utilized in which a filler with high softening point is inserted between fillers with low softening points. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solar cell module, and more particularly to a solar cell module with improved electrical insulation.

  Solar cell elements are often manufactured using a single crystal silicon substrate or a polycrystalline silicon substrate. For this reason, the solar cell element is vulnerable to physical impact, and when a solar cell is attached outdoors, it is necessary to protect it from rain. Moreover, since the electric output generated by one solar cell element is small, it is necessary to connect a plurality of solar cell elements in series and parallel so that a practical electric output can be taken out. For this purpose, a plurality of solar cell elements are connected using connection tabs as inner lead wires, sealed with a filler mainly composed of a translucent member and ethylene vinyl acetate copolymer (EVA), and the like. It is normal to create a module.

  FIG. 4 is a diagram illustrating an example of a structure of a panel portion of a conventional solar cell module.

  In FIG. 4, 1 is a translucent substrate, 2 is a light receiving surface side filler, 3 is a solar cell element, 4 is a back surface side filler, 5 is a back surface material, 6 is a connection tab, and 7 is an output wiring.

  As the translucent substrate 1, a substrate made of glass, polycarbonate resin or the like is used. Generally, white plate tempered glass having a thickness of about 3 mm to 5 mm is often used because of its weather resistance and light transmittance.

  The light-receiving surface side filler 2 and the back surface side filler 4 are formed into a sheet of about 0.4 to 1 mm in thickness of an ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) or polyvinyl butyral (hereinafter abbreviated as PVB). Is used. These are heated and pressed under reduced pressure by a laminating apparatus, so that they are softened and fused to be integrated with other members.

  In this way, in the solar cell module manufacturing process, heating and pressurizing a member under reduced pressure, softening and fusing the filler, and integrating with other members is called lamination.

  Furthermore, the solar cell element 3 is made of single crystal silicon or a polycrystalline silicon substrate having a thickness of about 0.3 to 0.4 mm as described above.

  The connection tab 6 electrically connects the solar cell elements 3 and is attached to the light receiving surface side electrode and the back surface side electrode of the solar cell element 3 by soldering.

  The output wiring 7 is for leading the electrical output generated in the solar cell element 3 to the outside, and is connected to the connection tab of the solar cell element 3 arranged at the end by soldering or the like.

  The back material 5 is a sheet that does not transmit moisture. In addition, a slit is provided at a predetermined position of the back material 5, and the output wiring 7 is previously drawn out from the slit to the surface of the back material 5 using tweezers or the like.

  Next, a method for manufacturing a conventional solar cell panel portion will be described.

In producing the panel portion of the solar cell module, the light receiving surface side filler 2, the solar cell element 3 connected to the connection tab 6 and the output wiring 7 on the translucent substrate 1, and the back surface side filler 4 thereon. The back material 5 is sequentially laminated. In such a state, it is set in a laminator and heated while being pressurized under reduced pressure, whereby the light-receiving surface side filler 2 and the back surface side filler 4 are melt-crosslinked and integrated. (Refer to the prior art of Patent Document 1)
JP 2000-332284 A

  The solar cell element 3 to which the connection tab 6 and the output wiring 7 are connected as described above is electrically insulated by the light receiving surface side filler 2 and the back surface side filler 4. However, when the solar cell element 3 connected in a straight line is distorted or the like, a convex portion may be formed on the connection tab between the solar cell element 3 and the solar cell element 3. Further, when the connection tab 6 and the output wiring 7 are connected to the solar cell element 3 by soldering, a convex portion by solder may be formed.

  FIG. 5 is a cross-sectional view after lamination schematically showing a state in which convex portions are formed on the connection tab and the soldered portion.

  In FIG. 5, 1 is a translucent substrate, 2 is a light receiving surface side filler, 3a and 3b are solar cell elements, 4 is a back surface side filler, 5 is a back surface material, 6 is a connection tab, and 10 is a convex portion by solder. , 11 is a gap between the convex portion of the connection tab and the translucent substrate, and 12 is a gap between the convex portion by solder and the back surface material.

  In this case, when a convex portion is formed in the connection tab or the soldered portion, the gap 11 between the convex portion of the connection tab and the translucent substrate, or the light receiving surface side filler 2 between the convex portion 10 of the solder and the gap between the translucent substrate is The thickness is reduced, and the electrical insulation performance of the solar cell module is degraded.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a solar cell module in which the electrical insulation performance does not deteriorate even when a convex portion is generated in a connection tab or a soldered portion. .

  In order to achieve the above object, in the present invention, in a solar cell module in which a solar cell element sealed with a filler is disposed between a translucent substrate and a back material, the solar cell element is disposed on the light receiving surface side of the solar cell element. The filler and / or the filler disposed on the back side of the solar cell element is composed of at least two kinds of fillers having different softening points.

  In addition, the filler includes a filler having a softening point of 45 to 55 ° C and a filler having a softening point of 80 to 90 ° C.

  The filler is formed by heating a filler sheet having a softening point of 45 to 55 ° C. and a filler sheet having a softening point of 80 to 90 ° C., and the filler on the side in contact with the solar cell element is It is formed of a filler having a low softening point.

  Also, the filler having a low softening point and the filler having a high softening point are all ethylene vinyl acetate copolymer (EVA), and the thickness of the filler having a high softening point is 0.03 mm or more, and 0.0. It is 3 mm or less.

  As described above, in the solar cell module in which the solar cell element sealed with the filler is disposed between the translucent substrate and the back surface material, the filler and / or the sun disposed on the light receiving surface side of the solar cell element. Fillers with different softening points including a filler with a high softening point are arranged between fillers with a low softening point between the fillers arranged on the back side of the battery element. As a result, for example, even when a convex portion is formed on a connection tab or a soldered portion, the thickness of the filler portion having a high softening point is ensured, and the insulation performance of the solar cell module is reduced. There is no.

  Further, the softening point of the filler having a low softening point is 45 to 55 ° C, and the softening point of the filler having a high softening point is 80 to 90 ° C, whereby the thickness of the filler portion having the high softening point is set. Can be reliably ensured, and the effect that the insulation performance of the solar cell module does not deteriorate can be ensured. In addition, since the filler with a low softening point is located on the solar cell element side, the laminating process softens from a low heating temperature, so the stress applied to the convex portions such as the connection tab and the soldered portion is not heated. Can be absorbed early.

  Further, the filler having a low softening point and the filler having a high softening point are all ethylene vinyl acetate copolymer (EVA), and the thickness of the filler having a high softening point is 0.03 mm or more and 0.3 mm. By making it below, it is possible to ensure the weather resistance and the like in addition to the electrical insulation performance of the solar cell module.

  Hereinafter, the solar cell module of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a light-receiving surface side filler or a back surface side filler used in the solar cell module of the present invention.

  In FIG. 1, 20 is a filler with a low softening point, 21 is a filler with a high softening point, and 22 is a filler with a low softening point. That is, the light-receiving surface side filler and / or the back surface side filler according to the present invention consists of three layers.

  The filler 20 having a low softening point in the first layer is a layer in contact with the solar cell element, and is made of EVA, PVB or the like, and its thickness is 0.2 to 0.00 in consideration of the reliability of the solar cell module. It is desirable to be about 8 mm. Furthermore, the softening point is set to 45 ° C. or higher and 55 ° C. or lower.

  The filler 21 having a high softening point of the second layer is an intermediate layer of the three layers, and is made of EVA, PVB, or the like, and the thickness is preferably about 0.03 to 0.3 mm. Furthermore, the softening point is 80 ° C. or higher and 90 ° C. or lower.

  That is, according to tests repeatedly conducted by the inventors, when the thickness of the filler 21 having a high softening point of the second layer is less than 0.03 mm, the electrical insulation performance may be reduced to 3000 V or less. The yield in the electrical insulation test in the module manufacturing process is reduced. If the thickness of the filler 21 having a high softening point in the second layer exceeds 0.3 mm, sealing of the solar cell element with the filler becomes insufficient, and oxidation of the electrode of the solar cell element occurs. As a result, the output of the solar cell module may decrease.

  The filling material 22 having a low softening point in the third layer is a layer in contact with the translucent substrate or the back surface material, and is made of EVA, PVB or the like, and its thickness ensures adhesion to the translucent substrate or the back surface material. And in order to ensure the reliability of a solar cell module, it is desirable to set it as about 0.1-0.2 mm. Furthermore, the softening point is set to 45 ° C. or higher and 55 ° C. or lower.

  Further, the filler 22 having a low softening point in the third layer is a material having the same composition as that of the filler 20 having a low softening point in the first layer. This is desirable because

  Further, the difference between the softening points of the filler having a low softening point and the filler having a high softening point is preferably 20 ° C. or higher in consideration of the temperature distribution of the laminator and the temperature fluctuation. Furthermore, the softening point of the filler having a low softening point is set to 45 ° C. or more and 55 ° C. or less, and the softening point of the filler having a high softening point is set to 80 ° C. or more and 90 ° C. or less. It is possible to improve the electrical insulation performance of the solar cell module without lowering the performance compared to the current one.

  Such a filler having a changed softening point can be produced by changing its composition. For example, in EVA, a cross-linking agent is added to a copolymer of ethylene and vinyl acetate. By increasing the ratio of the vinyl acetate content, the softening point can be lowered to an arbitrary temperature. Further, by lowering the ratio of vinyl acetate content, the softening point can be raised to an arbitrary temperature.

  In addition, the filler according to the present invention is particularly preferably EVA in consideration of its weather resistance and electrical insulation performance.

  Further, the size of the filler 20 having a low softening point, the filler 21 having a high softening point, and the filler 22 having a low softening point is determined by the adhesion of each member at the time of lamination, the sealing of solar cell elements, and the electrical insulation according to the present invention. In order to ensure the effect of improving the property, it is desirable to produce the same size as the translucent substrate used for the produced solar cell panel or about 1 to 3 mm larger.

  FIG. 2 is a cross-sectional view showing an example of the structure of the solar cell panel according to the present invention.

  2, 20a and 20b are fillers having a low softening point, 21a and 21b are fillers having a high softening point, 22a and 22b are fillers having a low softening point, 23 is a translucent substrate, 24 is a solar cell element, 25 Is a back material, 26 is a connection tab, and 27 is an output wiring.

  Each member will be described below.

  As the translucent substrate 23, a substrate having good light transmittance made of glass, polycarbonate resin or the like is used.

  As the glass plate, white plate glass, tempered glass, double tempered glass, heat ray reflective glass and the like are used, but generally white plate tempered glass having a thickness of about 3 mm to 5 mm is used.

  On the other hand, when a substrate made of a synthetic resin such as polycarbonate resin is used, a substrate having a thickness of about 5 mm is often used.

  A filler 22a having a low softening point on the light-receiving surface side is disposed on the light-transmitting substrate 23, a filler 21a having a high softening point on the light-receiving surface side is further disposed thereon, and a softening on the light-receiving surface side is further disposed thereon. A low-point filler 20a is placed. The filler 22a having a low softening point, the filler 21a having a high softening point, and the filler 20a having a low softening point have the above-described physical properties and dimensions.

  Furthermore, the filler 22a having a low softening point, the filler 21a having a high softening point, and the filler 20a having a low softening point may be prepared separately as described above, and may be stacked one by one. It is desirable to integrate in advance by sonic welding or the like because the number of steps can be reduced in the manufacturing process of the solar cell module.

  Further, the filler such as EVA can contain titanium oxide, pigment or the like and can be colored white, but the light-receiving surface-side fillers 20a, 21a, and 22a according to the present invention are solar cell elements when colored. Since the amount of light incident on 24 is reduced and the power generation efficiency is lowered, it is preferable to use a transparent material.

  The solar cell element 24 is made of, for example, a single crystal or polycrystalline silicon substrate having a thickness of about 0.3 to 0.4 mm and a size of about 150 mm square. The solar cell element 24 has a PN junction (not shown) in which a P layer containing a large amount of P-type impurities such as boron and an N layer containing a large amount of N-type impurities such as phosphorus are in contact with each other inside the silicon substrate. ing. Furthermore, an electrode is formed on a part of the light receiving surface side and the back surface side of the solar cell element 24 by applying silver paste by a screen printing method or the like, and these electrode surfaces are easily attached with protection and connection tabs 26. In order to achieve this, solder coating may be applied over almost the entire surface.

  In a normal solar cell module, a plurality of solar cell elements 24 are electrically connected using connection tabs 26 made of a highly conductive metal or the like. Such a connection tab 26 is usually used by cutting the entire surface of a copper foil or the like having a thickness of about 0.1 to 1.0 mm and a width of about 2 to 8 mm into a predetermined length.

  For example, when the solar cell elements 24 are connected in series, one end of the connection tab 26 is connected to the light-receiving surface side electrode of one solar cell element by soldering or the like, and the other end of the connection tab 26 is adjacent to the solar cell element. This is done by connecting to the back side electrode of the soldering by soldering or the like.

  The output wiring 27 is for leading out the electrical output of the solar cell element 24 to the outside of the solar cell module. Usually, the entire surface of the copper foil having a thickness of about 0.1 to 1.0 mm and a width of about 2 to 8 mm is formed. A solder-coated one is cut into a predetermined length and used. One end of the output wiring 27 is connected to the solar cell element 24 by soldering or the like, and the other end is connected to a terminal box (not shown) for connecting to an external circuit.

  The solar cell element 24 to which the connection tab 26 and the output wiring 27 are thus connected is placed on the substantially central portion of the filler 20a having a low softening point on the light receiving surface side.

  A filler 20b having a low softening point on the back side is disposed on the filler 20a having a low softening point on the light receiving surface on which the solar cell element 24 is placed, and a filler 21b having a high softening point on the back side is further disposed thereon. The filler 22b having a low softening point on the back surface side is further disposed thereon. The filler 20b having a low softening point, the filler 21b having a high softening point, and the filler 22b having a low softening point have the above-described physical properties and dimensions.

  Furthermore, the filler 20b having a low softening point, the filler 21b having a high softening point, and the filler 22b having a low softening point may be prepared separately as described above, and may be stacked one by one. It is desirable to integrate in advance by sonic welding or the like because the number of steps can be reduced in the manufacturing process of the solar cell module.

  Further, the back side fillers 20b, 21b, and 22b according to the present invention may be transparent materials, but may contain titanium oxide, pigments, etc. according to the installation environment around the solar cell module, and may be colored white. Also good.

  As the back material 25, a weather-resistant fluorine-based resin sheet in which an aluminum foil is sandwiched so as not to transmit moisture, a polyethylene terephthalate (PET) sheet on which alumina or silica is deposited, and the like are used. Further, a slit or opening is provided at a predetermined position of the back material 25, and the output wiring 27 is drawn out from the slit or opening to the surface of the back material 25 (external side of the solar cell module) using tweezers or the like. .

  Next, these laminating methods will be described.

  As described above, a superposition of each member is set in a device called a laminator, and pressurized while heating under reduced pressure.

  At this time, heating is first performed near the softening point of the filler having a low softening point. For example, if the softening point of a filler with a low softening point is 50 ° C., the temperature is controlled so that the entire laminate is within the temperature range of 47 to 53 ° C. in consideration of the temperature distribution and temperature change in the laminator. While heating under a reduced pressure of about 50 to 150 Pa, the entire laminate is pressurized as uniformly as possible at a pressure of about 10 to 100 KPa for about 1 to 15 minutes.

  Thereafter, the pressurization is stopped, and the set temperature of the laminator is changed so that the temperature of the laminate is near the softening point of the filler having a high softening point. For example, if the softening point of a filler with a high softening point is 85 ° C, the temperature is controlled so that the entire laminate is within the temperature range of 82 to 88 ° C, taking into account the temperature distribution and temperature change in the laminator. Leave for 1-15 minutes. Thereafter, the decompression and heating are stopped, and the completed solar cell panel is taken out from the laminator.

  FIG. 3 is a sectional view schematically showing an internal state of the solar cell panel according to the present invention.

  3, reference numerals 20a and 20b are fillers having a low softening point, fillers 21a and 21b are fillers having a high softening point, 22a and 22b are fillers having a low softening point, and 23 is a translucent substrate. , 24 is a solar cell element, 25 is a back material, 26 is a connection tab, 31 is a convex portion by solder, 30 is a gap between the convex portion of the connection tab and the translucent substrate, and 33 is a convex portion and back surface by the solder. The gap of the material is shown.

  In this way, first, the filler having a low softening point is softened and melted by pressurizing while heating in the vicinity of the softening point of the filler having a low softening point, thereby completely sealing the solar cell element. At this time, even when there is a convex portion of the connection tab as described above or a convex portion 31 by solder, the filler having a high softening point is not softened as shown in FIG. The gaps 30 and 33 between the optical substrate 23 and the back material 25 are maintained at intervals necessary for ensuring electrical insulation.

  Furthermore, the pressurization is stopped after that, and the temperature of the laminate is kept near the softening point of the filler having a high softening point, so that the fillers are integrated, and there is no air bubbles remaining inside. It can be set as a high solar cell module.

  A terminal box (not shown) provided with a cable for connecting an external circuit is attached to the back surface of the solar cell panel thus manufactured with an adhesive or the like. Furthermore, the required strength as a solar cell module and a module frame (not shown) required for installing the solar cell module in a building or the like are fitted on the outer periphery of the solar cell panel, and the corner is screwed to complete the solar cell module. To do.

  Further, a filler having a structure in which a filler having a high softening point is disposed between fillers having a low softening point according to the present invention is a method for receiving solar cell elements by using the solar cell element or solar cell module manufacturing method used. It may be used only on the surface side or the back surface side, or may be used on both the light receiving surface side and the back surface side.

  For example, in an amorphous silicon solar cell in which an electrode is disposed only on the light receiving surface side or the back surface side, it may be used only on the light receiving surface side or the back surface side of the solar cell element. Moreover, in the solar cell element using the above crystalline silicon substrate, since the electrodes are on both the light receiving surface side and the back surface side, it is desirable to use the filler according to the present invention on both surfaces.

  In addition, this invention is not limited to the said embodiment, Many corrections and changes can be added within the range of this invention. For example, the solar cell element is not limited to a crystalline solar cell such as a single crystal or polycrystalline silicon, and can be applied to a thin film solar cell. In addition, in the case of crystalline solar cell elements, the solder that coats the connection tab and the electrode of the solar cell element can also be applied to lead-free solder in addition to eutectic solder containing lead, and further, the electrode of the solar cell element Even those that are not solder coated can be applied.

It is a figure which shows the filler which concerns on this invention. It is sectional drawing which shows an example of the structure of the solar cell panel which concerns on this invention. It is sectional drawing which shows typically the state inside the solar cell panel which concerns on this invention. It is a figure which shows an example of the structure of the panel of the conventional solar cell module. It is sectional drawing after the lamination which shows typically the state which the convex part produced in the connection tab or the soldering part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 23: Translucent board | substrate 2: Light-receiving surface side filler 3, 3a, 3b, 24: Solar cell element 4: Back surface side filler 5, 25: Back surface material 6, 26: Connection tab 7, 27: Output wiring 10, 31: convex portion 11 by solder, 30: gap 12 between the convex portion of connection tab and translucent substrate, 33: gap between convex portion by solder and back material 20, 22, 20a, 20b, 22a, 22b : Fillers with low softening point 21, 21a, 21b: Fillers with high softening point

Claims (4)

In a solar cell module in which a solar cell element sealed with a filler is disposed between a translucent substrate and a back surface material,
The filler disposed on the light receiving surface side of the solar cell element and / or the filler disposed on the back surface side of the solar cell element is composed of at least two types of fillers having different softening points. Battery module. The solar cell module according to claim 1, wherein the filler includes a filler having a softening point of 45 to 55 ° C and a filler having a softening point of 80 to 90 ° C. The filler is formed by heating a filler sheet having a softening point of 45 to 55 ° C. and a filler sheet having a softening point of 80 to 90 ° C., and the filler on the side in contact with the solar cell element is softened. The solar cell module according to claim 1, wherein the solar cell module is formed of a filler having a low point. The filler having a low softening point and the filler having a high softening point are all ethylene vinyl acetate copolymer (EVA), and the thickness of the filler having a high softening point is 0.03 mm or more and 0.3 mm or less. The solar cell module according to claim 1, wherein the solar cell module is a solar cell module.

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