Patent Application
20150059835
The present disclosure relates to a photoelectric conversion device.
As a power generation system using sunlight, a photoelectric conversion panel in which semiconductor thin films of amorphous, microcrystal or the like are laminated is used. In applying such a photoelectric conversion panel to a solar photovoltaic system, it is installed as a photoelectric conversion device (module) which is equipped with a module frame member in an outer periphery part of the device.
On the other hand, a technique of welding glasses plates by irradiating laser beam having a pulse width of femtoseconds was disclosed.
In the super straight structure, there is a risk of ingress of moisture or the like into the back sheet 14 and the sealing member 12 permeating them if outdoor use of the structure continues for a long period of time. Further, there is also a risk of the occurrence of output reduction, failure such as disconnection, and changes in external appearance such as peeling of film due to ingress of moisture or the like from an end surface. Moreover, property improvement of a sealing member becomes necessary in order to improved long-term reliability, and a use amount of the member also increases, which could cause an increase in cost.
Further, it is difficult for the glass package structure to prevent ingress of moisture or the like from the end surface, and special end surface seal needs to be used, which incurs an increase in cost. Further, in a structure which does not use the module frame member 18, relative positions of the glass plate 10 and the glass plate 20 could be misaligned due to softening of the sealing member 12 during high temperature in summer.
Moreover, on a rear surface side of the photoelectric conversion elements which are formed on a front surface side on the glass plate 10, power-collecting wiring for collecting power or for extracting power outside the photoelectric conversion device, an insulative coating material for insulating the power-collecting wiring from rear surface electrodes of the photoelectric conversion elements, and the like are disposed, and a gap is generated between the glass plate 10 on a front surface side and the glass plate 20 on a rear surface side. If air is left in the gap, expansion/contraction of air occurs due to irradiation of sunlight or the like, and there is a risk of breakage of the glass plates 10, 20, ingress of water via the gap, or the like.
On the other hand, when the glass plate 10 and the glass plate 20 are pressure-bonded to make the gap smaller, stress is applied to the glass plate 20 by protrusions of a structure body on the rear surface of the photoelectric conversion elements, which could cause breakage.
One aspect of the present disclosure is a photoelectric conversion device which is provided with: a first glass plate; a photoelectric conversion unit which is fixed on the first glass plate and generates power according to an input of light; and a second glass plate which is disposed so as to cover the photoelectric conversion unit, in which at least a part of the periphery of the second glass plate and that of the first glass plate are melted and bonded to each other, and a plurality of photoelectric conversion elements are connected in series or parallel in the photoelectric conversion unit.
<Basic Constitution>
A photoelectric conversion device 200 in the first embodiment of the present disclosure is constituted by including a front surface glass plate (glass substrate) 30, a photoelectric conversion unit 32, and a rear surface glass plate 34 as shown in the external appearance plan view of
As the front surface glass plate 30, a glass plate of 1 m square and 4 mm thickness is applied for example. However, the invention is not limited to this, but may be any plate which is suitable for forming the photoelectric conversion unit 32 and capable of mechanically supporting the photoelectric conversion device 200. Input of light to the photoelectric conversion device 200 is performed basically from the front surface glass plate 30 side.
The photoelectric conversion unit 32 is formed on the front surface glass plate 30. The photoelectric conversion unit 32 is formed by laminating a transparent electrode, a photoelectric conversion unit, a rear surface electrode and the like. As the transparent electrode, a film formed by combining at least one type or plural types out of transparent conductive oxide (TCO) in which tin (Sn), antimony (Sb), fluorine (F), aluminum (Al) or the like is doped with tin oxide (SnO2), zinc oxide (ZnO), indium tin oxide (ITO) or the like, for example, can be used. Further, the photoelectric conversion unit should be an amorphous silicon photoelectric conversion unit (a-Si unit), a microcrystal silicon photoelectric conversion unit (μc-Si unit) or the like, for example. The photoelectric conversion unit may have a structure in which a plurality of the photoelectric conversion units are laminated such as a tandem type and a triple type. The rear surface electrode may be the transparent conductive oxide (TCO) reflective metal, or a laminated structure thereof. Tin oxide (SnO2), zinc oxide (ZnO), indium tin oxide (ITO) or the like is used as the transparent conductive oxide (TCO), and metal such as silver (Ag) and aluminum (Al) is used as the reflective metal.
The rear surface glass plate 34 is provided so as to cover the photoelectric conversion unit 32 formed on the front surface glass plate 30. The rear surface glass plate 34 has substantially the same size as the front surface glass plate 30 for example, and a glass plate having the thickness of 2 mm is applied. However, the plate is not limited to this.
The front surface glass plate 30 and the rear surface glass plate 34 are melted and bonded in a bonding region A of their outer peripheral regions. The bonding region A is provided for peripheral part B where the photoelectric conversion unit 32 is not formed in the front surface glass plate 30. The peripheral part B (region not hatched in
It should be noted that the photoelectric conversion device 200 may be provided with interconnectors 36 for extracting power generated in the photoelectric conversion unit 32 to the outside. Herein, the film thickness of the photoelectric conversion unit 32 is several μm and the thickness of the interconnectors 36 is approximately several hundred μm, so that when the width of the peripheral part B is approximately 10 mm, the four outer peripheral sides are completely adhered by elastic deformation of either the front surface glass plate 30 or the rear surface glass plate 34, and the plates can be melted and bonded in the bonding region A.
The cross-sectional view in
Further, the plan view in
<Melting and Bonding Method>
As shown in
It is preferred that the laser beam 52 be femtosecond laser beam. Specifically, it is preferred that the laser beam 52 have a pulse width of 1 nanosecond or less. Further, it is preferred that the laser beam 52 have a wavelength at which adsorption occurs on at least one of the front surface glass plate 30 and the rear surface glass plate 34. For example, it is preferred that the laser beam 52 have a wavelength of 800 nm. Moreover, it is preferred that the laser beam 52 irradiate at sufficient energy density and scanning speed as to melt the front surface glass plate 30 and the rear surface glass plate 34. For example, it is preferred that the laser beam 52 irradiate at pulse energy of 10 micro-joule (μJ) per one pulse. Further, it is preferred to scan the laser beam 52 at a scanning speed of 60 mm/minute. Further, the laser beam 52 may irradiate either from the front surface glass plate 30 side or the rear surface glass plate 34 side.
Now, in the case where the thickness of the photoelectric conversion unit 32 and the interconnectors 36 is large and a gap between the peripheral part of the front surface glass plate 30 and the rear surface glass plate 34 becomes larger, filler 54 may be filled in the gap, and the filler 54 is melted to melt and bond the front surface glass plate 30 and the rear surface glass plate 34 as shown in the cross-sectional view in
As the filler 54, it is preferred to apply a material including an element which is capable of melting and bonding the front surface glass plate 30 and the rear surface glass plate 34 such as Si, SiO, SiO2 and SiOx.
Further, the laser beam 52 can irradiate either from the front surface glass plate 30 side or the rear surface glass plate 34 side, so that in the case where the photoelectric conversion unit 32 (including silicon substrate) itself is thick like a crystalline silicon solar battery, a constitution in which the front surface of the filler 54 is melted and bonded with the front surface glass plate 30 and the rear surface of the filler 54 is melted and bonded with the rear surface glass plate 34 is acceptable as shown in
In such a case, a conventional sealing member 56 may be used in combination in order to planarize unevenness caused by the photoelectric conversion unit 32. Further, in order to further increase a sealing effect, a conventional end surface seal 58 and a conventional frame 60 may be used in combination.
Further, the bonding region A does not need to be a single line, and a plurality of the bonding regions A may be provided, as shown in the plan view in
The plan view in
The first power-collecting wirings 62 are provided on the rear surface electrode of the photoelectric conversion units 32 in an extending manner. The first power-collecting wirings 62 are formed to connect positive electrodes and negative electrodes of a photoelectric conversion layer which is divided in a parallel manner near end sides of the photoelectric conversion device 200. Therefore, the first power-collecting wirings 62 are provided in an extending manner along a direction orthogonal to a parallel divided direction of the photoelectric conversion layer. In the configuration example, the first power collecting wirings 62 are provided in an extending manner in vertical directions along end sides on right and left as shown in
Next, an insulating coating material 68 is arranged in order to form electrical insulation between the second power-collecting wirings 64 and the rear surface electrode. The insulating coating material 68 is provided in an extending manner on the rear surface electrode of the photoelectric conversion unit 32 from the vicinity of the first power-collecting wirings 62, which are provided along the end sides on right and left of the photoelectric conversion device 200, to a disposed position of the terminal box 66 at the central part, as shown in
The second power-collecting wirings 64 are provided in an extending manner from areas on the first power-collecting wirings on the right and left toward the central part of the photoelectric conversion device 200 along an area on the insulating coating material 68, as shown in
The rear surface of the photoelectric conversion device 200 is sealed by the rear surface glass plate 34. At this point, end part of the second power-collecting wirings 64 are pulled out through holes X provided near the attaching position of the terminal box 66 on the rear surface glass plate 34. Then, the end part of each of the second power-collecting wirings 64 is electrically connected to terminal electrodes in the terminal box 66 by soldering or the like, insulating resin 70 such as silicon is filled into a space in the terminal box 66, and the box is closed with a lid. It is preferred to attach the terminal box 66 in the vicinity of the holes X, which are used for pulling out the end part of each of the second power-collecting wirings 64, by adhering using silicon or the like.
The front surface glass plate 30 and the rear surface glass plate 34 are melted and bonded in the bonding region A of their outer peripheral regions. The bonding region A is provided for the peripheral part B where the photoelectric conversion unit 32 is not formed in the front surface glass plate 30. The peripheral part B (a region not hatched in
A photoelectric conversion device 300 in the second embodiment is constituted by including a sealing member 80 in addition to the front surface glass plate 30, the photoelectric conversion unit 32, and the rear surface glass plate 34 as shown in the cross-sectional view in
In the photoelectric conversion device 300, before covering the photoelectric conversion unit 32 by the rear surface glass plate 34, the sealing member 80 is coated on the rear surface of the photoelectric conversion unit 32, and covered by the rear surface glass plate 34 after baking.
Herein, it is preferred that the sealing member 80 be a material having a rate of thermal expansion closer to that of the front surface glass plate 30 and the rear surface glass plate 34, and it is preferred to use a silicon oxide based material. It is preferable that the silicon oxide-based material be a material containing SiC, SiO2 or SiO, by at least 50% or more as a main component. By using a silicon oxide-based material as the sealing member 80, coefficients of thermal expansion the front surface glass plate 30 and the rear surface glass plate 34 can be made closer, and occurrence of thermal stress between the front surface glass plate 30, the rear surface glass plate 34 and the sealing member 80, which arises from heating by sunlight irradiation or the like, can be suppressed. Therefore, breakage of the front surface glass plate 30, the rear surface glass plate 34 and the sealing member 80 caused by thermal stress can be prevented.
For example, silica sol (silica gel) which is formed by mixing microparticles of silicon oxide (glass) into a binder of resin such as acrylic resin or solvent such as water and organic solvent is coated by a spray coating method, a spin coater coating method or the like. Then, the sealing member 80 is solidified by heating at several tens of ° C. to several hundred ° C., covered by the rear surface glass plate 34, and the front surface glass plate 30 and the rear surface glass plate 34 are bonded.
As described, at least a part of a gap which occurs close to power collecting wirings, an insulating coating material or the like between the front surface glass plate 30 and the rear surface glass plate 34 is buried by the silicon oxide-based sealing member 80. In this way, air in the gap which occurs between the front surface glass plate 30 and the rear surface glass plate 34 is eliminated, any effect due to expansion/contraction of air can be reduced, and breakage of the front surface glass plate 30 or the rear surface glass plate 34 can be suppressed. Further, ingress of water via the gap between the front surface glass plate 30 and the rear surface glass plate 34 can be prevented.
With such a structure, the front surface glass plate 30 and the rear surface glass plate 34 can be melted and bonded without widely bending both plates. Therefore, bending stress applied to the front surface glass plate 30 and the rear surface glass plate 34 can be made smaller, and breakage of the front surface glass plate 30 or the rear surface glass plate 34 can be suppressed.
In this case, since the front surface glass plate 30 and the rear surface glass plate 34 are directly melted and bonded, bonding force can be increased. Further, glass plates are pressed against each other by bending of the front surface glass plate 30 or the rear surface glass plate 34, and adhesion property of the front surface glass plate 30 and the rear surface glass plate 34 can be improved. In this way, air between the front surface glass plate 30 and the rear surface glass plate 34 can be eliminated even more efficiently, which enhances an effect of suppressing breakage of the front surface glass plate 30 or the rear surface glass plate 34 caused by expansion/contraction of air. Further, ingress of water via the gap between the front surface glass plate 30 and the rear surface glass plate 34 can be also reduced more.
It should be noted that the structures of
Even with this structure, similarly to the example in
Further, in the examples in
Now, a similar effect can be obtained by treatment in which the sealing member 80 is completely solidified in a region other than the peripheral part of the photoelectric conversion device 300, then the sealing member 80 is newly coated on the peripheral part only, and covered by the rear surface glass plate 34 in a state where the material is not completely solidified.
A photoelectric conversion device 400 in a third embodiment has a constitution similar to the photoelectric conversion device 100 in the first embodiment, in which air in the gap between the front surface glass plate 30 and the rear surface glass plate 34 is discharged into a decompressed state to the atmospheric.
In laminating the photoelectric conversion device 400, after the front surface glass plate 30 and the rear surface glass plate 34 are melted and bonded in the bonding region A as shown in
At this point, air collected in the gap between the front surface glass plate 30 and the rear surface glass plate 34 is simultaneously exhausted from the openings C, and the openings are sealed in a state where pressure in the gap between the front surface glass plate 30 and the rear surface glass plate 34 is decompressed more than atmospheric pressure.
As described, air in the gap, which occurs because of the power-collecting wiring, the insulating coating material or the like between the front surface glass plate 30, and the rear surface glass plate 34, can be exhausted. In this way, affect of expansion/contraction of air in the gap between the front surface glass plate 30 and the rear surface glass plate 34 can be reduced, and breakage of the front surface glass plate 30 or the rear surface glass plate 34 can be suppressed. Further, ingress of water via the gap between the front surface glass plate 30 and the rear surface glass plate 34 can be prevented.
It should be noted that the constitution in which sealing is performed in the state where air between the front surface glass plate 30 and the rear surface glass plate 34 is exhausted can be similarly applied in the constitution shown in
Further, in the third embodiment, air between the front surface glass plate 30 and the rear surface glass plate 34 is exhausted from the openings C for pulling out the wiring cords 38 to the outside, and the openings C are sealed in the exhausted state, but the invention is not limited to this. A constitution in which openings other than the openings for pulling out the wiring cords 38 are provided for the photoelectric conversion device, air between the front surface glass plate 30 and the rear surface glass plate 34 is exhausted from the openings, and the openings are sealed by the sealing members 82, is also acceptable.
A photoelectric conversion device 600 in the fourth embodiment of the present disclosure is constituted by including the front surface glass plate 30, photoelectric conversion units 602, and the rear surface glass plate 34 as shown in the external appearance plan view in
The photoelectric conversion element is a rear surface bonding photoelectric conversion element in which both of a positive side electrode 104 and a negative side electrode 106 are provided on a rear surface side being the opposite side of the light receiving surface, as shown in the plan view seen from the rear surface side being the opposite side of the light receiving surface in
The serial interconnectors 108 are electrically connected severally to the positive side electrode 104 and the negative side electrode 106 at both ends of a photoelectric conversion unit 102 (right and left ends in
By having the constitution in which the photoelectric conversion elements are connected in series or parallel in this manner, voltage and current which are optimum for inputting a load or a power conditioner connected to the photoelectric conversion device 600 can be extracted. It should be noted that the photoelectric conversion element is not limited to the rear surface bonding photoelectric conversion element, but thin-film photoelectric conversion elements having at least a pair or PIN junctions may be connected in series or parallel for example.
A photoelectric conversion device 700 in a fifth embodiment of the present disclosure is constituted by including low-refractive-index layer 112 on the front surface glass plate in addition to the front surface glass plate 30, the photoelectric conversion unit 602, and the rear surface glass plate 34 as shown in
The front surface glass plate 30 is a tempered glass plate with a thickness of 1.8 mm, and which is fabricated by an air-cooling and tempering method. The front surface glass plate 30 has higher tolerance to damage caused by wind and rain in outdoor use compared to the non-tempered front surface glass plate 34.
As shown in
Further, the low-refractive-index layer 112 may be formed on the front surface glass plate 30 as shown in
A photoelectric conversion device 800 in a sixth embodiment of the present disclosure is provided with terminal boxes 116 for extracting generated electric current on the rear surface glass plate 34 as shown in
A current extraction part of the photoelectric conversion device 800 consists of the serial interconnector 108, solder 118, a metal wire 120, and a low-melting-point glass 122. Firstly, the metal wire 120 is allowed to go through a through hole 34a provided for the rear surface glass plate 34, and a gap between the through hole 34a and the metal wire 120 is filled by the low-melting-point glass 122. In this way, extraction wiring for generated electric power through the rear surface glass plate 34 is formed by the metal wire 120, and the rear surface glass plate 34 is airtightly sealed by the low-melting-point glass 122. The metal wire 120 should be an alloy of iron and nickel in a ration of 50:50 for example. Such an alloy has a coefficient of thermal expansion relatively close to the coefficient of thermal expansion of the low-melting-point glass 122, and cracking caused by thermal expansion in airtight sealing can be suppressed. Then, tip of the metal wire 120 is connected to the serial interconnector 108 of the photoelectric conversion unit 602, which is disposed on the front surface glass plate 30, via the solder 118. The solder 118 is disposed for the tip of the serial interconnector 108 or the metal wire 120 in advance, and the serial interconnector 108 and the metal wire 120 can be connected by melting through heating the solder via the metal wire 120 exposed outside. Then, in this embodiment as well, at least a part of the front surface glass plate 30 and that of the rear surface glass plate 34 are melted and bonded to each other in the bonding region A.
The terminal box 116 includes a cable 124, solder 126 and insulating resin 128. The cable 124 is connected to the metal wire 120 by the solder 126. The terminal box 116 is adhered to the rear surface glass plate 34 by the insulating resin 128. The insulating resin 128 has a relatively high water vapor barrier property, but is likely to be affected by water vapor in the long run. However, if the structure of the current extraction part such as the photoelectric conversion device 800 is adopted, moisture ingress does not reach the photoelectric conversion element, and a highly airtight photoelectric conversion device can be obtained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-123304 | May 2012 | JP | national |
The present application is a continuation under 35 U.S.C. §120 of PCT/JP2013/001215, filed on Feb. 28, 2013, which is incorporated herein by reference and which claimed priority to Japanese Patent Application No. 2012-123304 filed on May 30, 2012. The present application likewise claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2012-123304 filed on May 30, 2012, the entire content of which is also incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2013/001215 | Feb 2013 | US |
| Child | 14527516 | US |
