JP2004087986A - Solar battery element and solar battery module - Google Patents

Solar battery element and solar battery module Download PDF

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JP2004087986A
JP2004087986A JP2002249676A JP2002249676A JP2004087986A JP 2004087986 A JP2004087986 A JP 2004087986A JP 2002249676 A JP2002249676 A JP 2002249676A JP 2002249676 A JP2002249676 A JP 2002249676A JP 2004087986 A JP2004087986 A JP 2004087986A
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solar cell
cell element
output extraction
metal
electrode
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JP4199495B2 (en
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Yuko Fukawa
府川　祐子
Kenji Fuseya
伏谷　健司
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Kyocera Corp
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Kyocera Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a solder ball and a projection part are formed due to flow-out of excess solder of an output picking part of a rear electrode to the circumferential edge part of an inner lead in thermal welding of an electrode of the solar battery element and the inner lead, and warpages or the like are generated in the solar battery element by the output picking-up part of the rear electrode. <P>SOLUTION: A surface electrode is formed in one major surface side of a semiconductor substrate 1 with a semiconductor junction part, and a rear electrode, consisting of a current collector 5 by a first metal and an output picking-up part 6 by a second metal of better solder wettability than that of the first metal is formed in the other major surface side in a solar battery element 7. A projection part 13 is provided on the output picking-up part 6 and the length of a projection part 13 located in an end part of the semiconductor substrate 1 is made shorter than the length of a projection part 13, located in a central part. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は太陽電池素子および太陽電池モジュールに関し、特に裏面電極を集電部と出力取出部とで構成した太陽電池素子およびその太陽電池素子を用いた太陽電池モジュールに関する。
【０００２】
【従来の技術】
従来の太陽電池素子を図４に示す。例えばＰ型半導体基板１の表面近傍全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を設け、半導体基板１の表面に窒化シリコン膜などから成る反射防止膜３を設け、表面に表面電極４を設けるとともに、裏面にはアルミニウムなどから成る集電部５と銀などから成る出力取出部６とで構成される裏面電極を設けている。
【０００３】
このような太陽電池素子７は、図５に示すように、複数の素子同士をインナーリード８を用いて直列に接続して、電圧を昇圧させて使用するのが一般的である。この素子７間の接続にははんだが必要となるため、表面電極４および裏面電極の出力取出部６にはんだ濡れ性が良好な素材を用いて太陽電池素子７の電極にはんだコーティングを行っている。はんだコーティングの方法としては、はんだ槽に太陽電池素子７を浸漬させる方法が一般的である。
【０００４】
複数の太陽電池素子７を接続するには、インナーリード８の一方端を表面電極４のバスバー部１６（図８参照）上の略全長にわたって配設し、その全長もしくは複数個所をホットエアーや半田ごてなどを用いて熱溶着することによって表面電極４に接続するとともに、インナーリード８の他方端を、隣接する素子７の裏面の出力取出部６上に配設し、その全長もしくは複数個所を溶着することによって出力取出部６に接続する。
【０００５】
その後、図６に示すように受光面側にガラスなどからなる透光性パネル９を配置し、裏面側の鋼板入りフィルムなどからなる裏面保護材１０との間に、複数の太陽電池素子７を直列および並列に接続してＥＶＡ（エチレン−酢酸ビニル共重合体）などの透明な充填材１１で封入し、さらに図７に示すように、アルミ押出形材等からなるフレーム部材１２を周縁部に取り付けている。
【０００６】
【発明が解決しようとする課題】
しかし、この従来の太陽電池モジュールでは、太陽電池素子７の電極４、６とインナーリード８とを熱溶着する際に、裏面電極の出力取出部６の余剰なはんだがインナーリード８の周縁部に流れ出したり凝集したりして、はんだ玉や突起部を形成する。表面側では、図８に示すように、通常バスバー部１６と直交するように、複数本のフィンガー電極１７が形成されているので、この問題は起こりにくい。しかし、裏面側は、図９に示す従来のパターンによると、余剰なはんだでも出力取出部６の外には流れ出ないので、インナーリード８の周縁部に凝集したりして、はんだ玉や突起部を形成するという問題が起こりやすい。
【０００７】
はんだ玉や突起部がインナーリード８の周縁部などに形成された状態でガラスなどの透光性パネル９と、裏面側の鋼板入りフィルムなどからなる裏面保護材１０との間に、複数の太陽電池素子７を直列および並列に接続してＥＶＡ（エチレン−酢酸ビニル共重合体）などの透明な充填材１１でラミネートすると、はんだ玉や突起部に局部的に力がかかり、太陽電池素子７が割れるという問題があった。この問題は、ガラスなどの硬質の透光性パネル９と裏面保護材１０との間に太陽電池素子を封入したときに多く発生していた。
【０００８】
この問題を防ぐ方法として、特願２００２−１８７３８６では、図１０に示すように、太陽電池素子７の裏面側に形成する出力取出部６に突出部を設けることが示されている。この方法によれば、出力取出部６上にインナーリード８を配置して半田ごてやホットエアーなどで熱溶着する際には、出力取出部６上の余剰なはんだは突出部１３に流れる。それによりインナーリードの熱溶着の際に、インナーリードの周縁部に余剰なはんだが凝集して、はんだ玉や突起部が形成されることを極力抑えることができる。
【０００９】
しかしこの方法によると、突出部１３を設けたことで、膨張係数の異なるシリコンとアルミニウムと銀との重なり部分が大きくなることから、局部的な応力が発生し、太陽電池素子に反りが発生し、後工程での割れの原因となっていた。
【００１０】
本発明は、このような従来技術の問題点に鑑みてなされたものであり、太陽電池素子の電極とインナーリードとを熱溶着する際に、裏面電極の出力取出部の余剰なはんだがインナーリードの周縁部に流れ出したり凝集したりして、はんだ玉や突起部が形成されるという問題を解消するとともに、太陽電池素子の割れ発生率も低減した太陽電池素子とそれを用いた太陽電池モジュールを提供することを目的とする。
【００１１】
【課題を解決するための手段】
上記目的を達成するために、請求項１に係る太陽電池素子においては、半導体接合部を有する半導体基板の一主面側に表面電極を形成するとともに、他の主面側に第一の金属による集電部と、この第一の金属よりも半田濡れ性のよい第二の金属による出力取出部とから成る裏面電極とを形成した太陽電池素子において、前記出力取出部に突出部を設けるとともに、前記半導体基板の端部に位置する突出部の長さを中央部に位置する突出部の長さよりも短くしたことを特徴とする。
【００１２】
上記太陽電池素子では、前記出力取出部を帯状に形成し、かつ長手方向の少なくとも一方側に前記集電部に向かって突出する複数の突出部を設けることが望ましい。
【００１３】
また、上記太陽電池素子では、前記出力取出部の突出部を前記集電部上もしくはその一部は前記集電部と重なることが望ましい。
【００１４】
また、上記太陽電池素子では、前記出力取出部の突出部以外の領域は全面もしくは部分的に前記半導体基板と接していることが望ましい。
【００１５】
また、上記太陽電池素子では、前記出力取出部を帯状に形成し、かつ長手方向において島状に分断して形成してもよい。
【００１６】
また、上記太陽電池素子では、前記第一の金属はアルミニウムを主成分とすることが望ましい。
【００１７】
また、上記太陽電池素子では、前記第二の金属は銀を主成分とすることが望ましい。
【００１８】
請求項８に係る太陽電池モジュールでは、上記太陽電池素子の表面電極と隣接する太陽電池素子の裏面電極の出力取出部とをインナーリードで接続することを特徴とする。
【００１９】
【発明の実施の形態】
以下、本発明の実施形態を添付図面に基づき詳細に説明する。
本発明に係る太陽電池素子の構造も基本的には従来の太陽電池素子と同様である。すなわち、図４に示すように例えばＰ型半導体基板１の表面近傍全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を設け、半導体基板１の表面に窒化シリコン膜などから成る反射防止膜３を設け、表面に表面電極４を設けるとともに、裏面にはアルミニウムなどから成る集電部５と銀などから成る出力取出部６とで構成される裏面電極を設けている。
【００２０】
このような太陽電池素子は、例えばＰ型半導体基板１をＮ型不純物雰囲気中で熱処理などして、表面領域の全面に一定の深さまでＮ型不純物を拡散させてＮ型を呈する拡散層２を形成し、ＣＶＤ法などで反射防止膜３を形成して拡散層２を分離したのち、表面に銀ペーストを、裏面にはアルミニウムペーストおよび銀ペーストをスクリーン印刷して焼成することにより表面電極４並びに集電部５および電極取出部６から成る電極が形成される。
【００２１】
図１に、請求項１に係る太陽電池素子の一例を示す。半導体基板１の裏面側の略全面に形成されたアルミニウムなどを主成分とする第一の金属による集電部５と、第一の金属よりも半田濡れ性のよい銀などを主成分とする第二の金属による出力取出部６から成る裏面電極を形成し、この出力取出部６に突出部１３を形成している。このような突出部１３を設けることにより、裏面電極の出力取出部６上にインナーリード８を配設し、半田ごてやホットエアーなどを用いて熱溶着する際に、出力取出部１３上の余剰なはんだは突出部１３に流れ、従来問題であったインナーリード８の周縁部に凝集したりして、はんだ玉や突起部を形成するという問題を解決できる。また太陽電池素子の端部に位置する突出部の長さを、中央部に位置する前記突出部の長さよりも短く形成している。これにより、熱膨張係数の違いにより発生する応力を、太陽電池素子７の中央部よりも端部で低減できる。これにより、太陽電池素子７の端面に割れの起点が発生することを防止でき、後工程での割れの発生を低減できる。
【００２２】
なお、この突出部１３は、出力取出部１３が帯状に形成される場合は、その長手方向の両側に複数設けることが望ましいが、図２に示すように長手方向の一方側のみに設けてもよい。
【００２３】
また、出力取出部６の突出部１３を、集電部５の上もしくは一部が重なるように設けておくことにより、集電部５のアルミニウムと出力取出部６の銀が合金化され、突出部１３のはんだ濡れ性が若干悪くなる。これにより、インナーリード８を熱溶着する前は、出力取出部６のうち突出部１３のはんだ付着量は他よりも少なくなるように制御することができる。
【００２４】
さらに出力取出部６の突出部１３以外の領域は全面もしくは部分的に銀と半導体基板が接していれば、太陽電池素子７の裏面電極の密着強度も確保できる。
【００２５】
図３に、本発明の他の実施形態を示す。この太陽電池素子では、出力取出部１３を全体として帯状に形成し、かつ長手方向において島状に分断して形成し、さらにその両側に突出部１３を形成したものである。このように出力取出部５を長手方向において島状に分断することにより、アルミニウムよりも高価な銀の使用量を削減することができる。また、はんだコーティングを行うときの突出部１３へのはんだの流れ込み量をさらに減少させることができる。これにより後工程でインナーリード８を溶着する際に、突出部１３にはんだが流れ込んでも、突出部１３にはんだ玉や突起が形成されることを極力抑えることができる。
【００２６】
また、これらの素子の裏面電極の出力取出部６上にインナーリード８を配設し、半田ごてやホットエアーなどを用いて熱溶着する際に、出力取出部１３上の余剰なはんだは突出部１３に流れ、従来問題であったインナーリード８の周縁部に凝集したりして、はんだ玉や突起部を形成するという問題を解決できるとともに、太陽電池素子７の端部の熱膨張係数の違いによる応力を中央部より低減できる。これにより、ラミネートするときにはんだ玉や突起部に局部的に力がかかったり、太陽電池の反りにより、太陽電池素子が割れるという問題を解消できる。
【００２７】
また、図を用いて説明した裏面電極の出力取出部は直線状に構成されているが、曲線状に構成することも可能である。さらに、各図には出力取出部６を半導体基板１の略全長にわたって形成するように記載したが、出力取出部６はインナーリード８との溶着予定位置に限定して形成することも可能である。
【００２８】
請求項８に係る発明では、上述のような太陽電池素子を用いて、その表面電極４と隣接する太陽電池素子の裏面電極の出力取出部６とをインナーリードで接続する。所望の出力が得られるように、多数の太陽電池素子を直並列に接続した状態でガラスなどの透光性パネルと裏面側の鋼板入りフィルムなどからなる裏面保護材との間に配設してＥＶＡ（エチレン−酢酸ビニル共重合体）などの透明な充填材１１でラミネートする。この場合、電極部分のはんだ玉や突起部の発生は極力低減されており、太陽電池素子端部の応力集中も低減されていることから太陽電池素子が割れることは極力低減できる。
【００２９】
なお、本発明は、上記実施形態に限定されるものではなく、本発明の範囲内で多くの修正および変更を加えることができる。例えば複数の突出部の形状や突出方向を異なるように形成してもよい。
【００３０】
【発明の効果】
以上のように、請求項１に係る太陽電池素子によれば、半導体基板の裏面側に形成した裏面電極の出力取出部に突出部を設けるとともに、端部に位置する突出部の長さを、中央部に位置する突出部の長さよりも短く形成したことから、裏面電極の出力取出部上にインナーリードを配置して半田ごてやホットエアーなどで熱溶着する際には、出力取出部上の余剰なはんだは突出部に流れ、もって余剰なはんだがインナーリードの周縁部に凝集したりしてはんだ玉や突起部を形成することを極力低減でき、後工程での太陽電池素子の割れなどを防止できるとともに、熱膨張係数の違いによって発生する応力を太陽電池素子の中央部よりも端部で低減でき、太陽電池素子の端面に割れの起点が発生することを防止でき、後工程での割れの発生を低減できる。
【００３１】
また、請求項８に係る太陽電池モジュールでは、半導体基板の裏面側に形成した裏面電極の出力取出部に突出部を設けた太陽電池素子を用いることから、インナーリードを熱溶着する際に、出力取出部上の余剰なはんだは突出部に流れ、もって余剰なはんだがインナーリードの周縁部に凝集したりしてはんだ玉や突起部を形成することを極力低減でき、ラミネートするときにはんだ玉や突起部に起因する太陽電池素子の割れを防止できるとともに、太陽電池素子の端面での割れの起点の発生を低減していることからも太陽電池素子の割れを防止でき、特にガラスなどの硬質の透光性パネルと裏面保護材との間に太陽電池素子を封入しても、セル割れの問題は発生しない。
【図面の簡単な説明】
【図１】本発明に係る太陽電池素子の裏面構造を示す図である。
【図２】本発明に係る太陽電池素子の他の裏面構造を示す図である。
【図３】本発明に係る太陽電池素子の他の裏面構造を示す図である。
【図４】従来の太陽電池素子を説明するための図である。
【図５】従来の太陽電池素子の接続状態を説明するための図である。
【図６】従来の太陽電池モジュールの構造を説明するための図である。
【図７】従来の太陽電池モジュールの構造を説明するための図である。
【図８】従来の太陽電池素子の表面電極部分を示す図である。
【図９】従来の太陽電池素子の裏面電極部分を示す図である。
【図１０】従来の太陽電池素子の他の裏面電極部分を示す図である。
【符号の説明】
１・・・半導体基板、２・・・拡散層、３・・・反射防止膜、４・・・表面電極、５・・・集電部、６・・・出力取出部、７・・・太陽電池素子、８・・・インナーリード、９・・・透光性パネル、１０・・・裏面保護部材、１１・・・充填材、１２・・・フレーム部材、１３・・・突出部、１４・・・穴、１５・・・太陽電池モジュール、１６・・・バスバー部、１７・・・フィンガー電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solar cell element and a solar cell module, and more particularly to a solar cell element having a back electrode formed of a current collector and an output extraction section, and a solar cell module using the solar cell element.
[0002]
[Prior art]
FIG. 4 shows a conventional solar cell element. For example, an N-type impurity is diffused to a certain depth over the entire surface near the surface of the P-type semiconductor substrate 1 to provide an N-type diffusion layer 2, and an anti-reflection film 3 made of a silicon nitride film or the like is provided on the surface of the semiconductor substrate 1. In addition, a front surface electrode 4 is provided on the front surface, and a back surface electrode formed of a current collecting unit 5 made of aluminum or the like and an output extraction unit 6 made of silver or the like is provided on the back surface.
[0003]
As shown in FIG. 5, such a solar cell element 7 is generally used by connecting a plurality of elements in series using an inner lead 8 and increasing the voltage. Since solder is required for the connection between the elements 7, the electrodes of the solar cell element 7 are coated with solder by using a material having good solder wettability for the output extraction portion 6 of the front electrode 4 and the back electrode. . As a method of solder coating, a method of dipping the solar cell element 7 in a solder bath is general.
[0004]
In order to connect the plurality of solar cell elements 7, one end of the inner lead 8 is arranged over substantially the entire length of the surface electrode 4 on the bus bar portion 16 (see FIG. 8), and the entire length or a plurality of locations is hot air or soldered. The other end of the inner lead 8 is disposed on the output extraction portion 6 on the back surface of the adjacent element 7 while being connected to the surface electrode 4 by heat welding using a trowel or the like. It is connected to the output extraction unit 6 by welding.
[0005]
Thereafter, as shown in FIG. 6, a light-transmitting panel 9 made of glass or the like is arranged on the light-receiving surface side, and a plurality of solar cell elements 7 are placed between the light-receiving panel 9 and a back surface protective material 10 made of a steel sheet-containing film or the like. Connected in series and in parallel, sealed with a transparent filler 11 such as EVA (ethylene-vinyl acetate copolymer), and further, as shown in FIG. Attached.
[0006]
[Problems to be solved by the invention]
However, in this conventional solar cell module, when the electrodes 4 and 6 of the solar cell element 7 and the inner lead 8 are thermally welded, excess solder of the output extraction portion 6 of the back electrode is formed on the peripheral edge of the inner lead 8. It flows out and agglomerates to form solder balls and protrusions. On the front surface side, as shown in FIG. 8, a plurality of finger electrodes 17 are formed so as to be orthogonal to the normal bus bar portion 16, so that this problem is unlikely to occur. However, according to the conventional pattern shown in FIG. 9, even the excess solder does not flow out of the output extraction portion 6 on the rear surface side, so that the solder may agglomerate on the peripheral portion of the inner lead 8 to form solder balls or protrusions. Is liable to occur.
[0007]
A plurality of solar cells are provided between a translucent panel 9 made of glass or the like and a back surface protection material 10 made of a film containing a steel plate on the back surface in a state in which solder balls and protrusions are formed on the periphery of the inner lead 8. When the battery elements 7 are connected in series and in parallel and laminated with a transparent filler 11 such as EVA (ethylene-vinyl acetate copolymer), a local force is applied to solder balls and protrusions, and the solar cell elements 7 There was a problem of cracking. This problem often occurs when a solar cell element is sealed between a hard translucent panel 9 made of glass or the like and a back surface protective material 10.
[0008]
As a method for preventing this problem, Japanese Patent Application No. 2002-187386 discloses that, as shown in FIG. 10, a projecting portion is provided on an output extraction portion 6 formed on the back surface side of a solar cell element 7. According to this method, when the inner leads 8 are arranged on the output extraction portion 6 and are thermally welded with a soldering iron, hot air, or the like, excess solder on the output extraction portion 6 flows to the projecting portion 13. Thus, during thermal welding of the inner leads, it is possible to minimize the formation of solder balls and protrusions due to the aggregation of excess solder on the peripheral edge of the inner leads.
[0009]
However, according to this method, since the overlapping portion of silicon, aluminum, and silver having different expansion coefficients becomes large due to the provision of the protruding portion 13, local stress is generated, and the solar cell element is warped. , Causing cracks in the subsequent process.
[0010]
The present invention has been made in view of such a problem of the related art, and when soldering an electrode of a solar cell element and an inner lead, excess solder in an output extraction portion of the back electrode is removed by the inner lead. In addition to eliminating the problem that solder balls and protrusions are formed by flowing out or agglomerating on the peripheral edge of the solar cell, a solar cell element and a solar cell module using the same that also reduce the rate of occurrence of cracks in the solar cell element The purpose is to provide.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the solar cell element according to claim 1, a surface electrode is formed on one main surface side of a semiconductor substrate having a semiconductor junction, and a first metal is formed on another main surface side. In a solar cell element in which a current collecting portion and a back electrode composed of an output extraction portion made of a second metal having better solder wettability than the first metal are formed, a projection is provided on the output extraction portion, The length of the protrusion located at the end of the semiconductor substrate is shorter than the length of the protrusion located at the center.
[0012]
In the above-mentioned solar cell element, it is preferable that the output take-out portion is formed in a belt shape, and a plurality of protrusions protruding toward the current collector are provided on at least one side in the longitudinal direction.
[0013]
Further, in the above-mentioned solar cell element, it is preferable that the projecting portion of the output take-out portion is on the current collecting portion or a part thereof overlaps with the current collecting portion.
[0014]
Further, in the above-mentioned solar cell element, it is desirable that a region other than the protruding portion of the output extraction portion is entirely or partially in contact with the semiconductor substrate.
[0015]
Further, in the above-mentioned solar cell element, the output extraction portion may be formed in a band shape and divided into island shapes in the longitudinal direction.
[0016]
Further, in the above solar cell element, it is preferable that the first metal contains aluminum as a main component.
[0017]
In the above-described solar cell element, it is preferable that the second metal contains silver as a main component.
[0018]
The solar cell module according to claim 8 is characterized in that the front electrode of the solar cell element is connected to the output extraction portion of the back electrode of the adjacent solar cell element by an inner lead.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The structure of the solar cell element according to the present invention is basically the same as the conventional solar cell element. That is, as shown in FIG. 4, for example, an N-type impurity is diffused to a certain depth over the entire surface near the surface of the P-type semiconductor substrate 1 to provide an N-type diffusion layer 2, and a silicon nitride film or the like is formed on the surface of the semiconductor substrate 1. An anti-reflection film 3 is provided, a front surface electrode 4 is provided on the front surface, and a back surface electrode composed of a current collecting unit 5 made of aluminum or the like and an output extraction unit 6 made of silver or the like is provided on the back surface.
[0020]
In such a solar cell element, for example, a P-type semiconductor substrate 1 is heat-treated in an N-type impurity atmosphere to diffuse an N-type impurity to a certain depth over the entire surface region to form an N-type diffusion layer 2. After forming the antireflection film 3 by the CVD method or the like and separating the diffusion layer 2, the surface electrode 4 and the surface electrode 4 An electrode composed of the current collecting unit 5 and the electrode extracting unit 6 is formed.
[0021]
FIG. 1 shows an example of the solar cell element according to claim 1. A current collector 5 made of a first metal mainly composed of aluminum or the like formed on substantially the entire back surface side of the semiconductor substrate 1 and a second current collector mainly made of silver or the like having better solder wettability than the first metal. A back electrode composed of an output portion 6 made of a second metal is formed, and a projection 13 is formed on the output portion 6. By providing such a protruding portion 13, the inner lead 8 is arranged on the output extraction portion 6 of the back electrode, and when the inner lead 8 is thermally welded using a soldering iron, hot air, or the like, the inner lead 8 is formed on the output extraction portion 13. Excess solder flows to the protruding portion 13 and aggregates on the peripheral portion of the inner lead 8, which has been a problem in the related art, thereby solving the problem of forming solder balls and protrusions. Further, the length of the protrusion located at the end of the solar cell element is formed shorter than the length of the protrusion located at the center. Thereby, the stress generated due to the difference in the coefficient of thermal expansion can be reduced at the end of the solar cell element 7 rather than at the center. Thereby, it is possible to prevent the occurrence of a crack starting point on the end face of the solar cell element 7 and to reduce the occurrence of cracks in a subsequent process.
[0022]
In the case where the output take-out portion 13 is formed in a strip shape, it is desirable that a plurality of the protrusions 13 be provided on both sides in the longitudinal direction. However, as shown in FIG. Good.
[0023]
In addition, by providing the projecting portion 13 of the output extracting portion 6 so that the upper portion or a part of the current collecting portion 5 overlaps, aluminum of the current collecting portion 5 and silver of the output extracting portion 6 are alloyed, and The solder wettability of the part 13 is slightly deteriorated. Thereby, before the inner lead 8 is thermally welded, it is possible to control the amount of solder adhered to the protruding portion 13 of the output extraction portion 6 to be smaller than the others.
[0024]
Furthermore, if the silver and the semiconductor substrate are entirely or partially in contact with the semiconductor substrate in a region other than the protruding portion 13 of the output extraction portion 6, the adhesion strength of the back electrode of the solar cell element 7 can be ensured.
[0025]
FIG. 3 shows another embodiment of the present invention. In this solar cell element, the output extraction portion 13 is formed in a band shape as a whole, divided into island shapes in the longitudinal direction, and furthermore, the protruding portions 13 are formed on both sides thereof. By dividing the output extraction portion 5 into islands in the longitudinal direction in this way, it is possible to reduce the amount of silver that is more expensive than aluminum. Further, the amount of solder flowing into the protruding portion 13 when performing solder coating can be further reduced. Thereby, when the inner lead 8 is welded in a later step, even if the solder flows into the protrusion 13, the formation of solder balls and protrusions on the protrusion 13 can be suppressed as much as possible.
[0026]
In addition, when the inner leads 8 are provided on the output extraction portions 6 of the back electrodes of these elements, and when heat welding is performed using a soldering iron or hot air, excess solder on the output extraction portions 13 is projected. In addition, the problem of forming a solder ball or a protrusion by condensing on the peripheral portion of the inner lead 8, which has been a problem in the related art, and solving the problem of the thermal expansion coefficient of the end of the solar cell element 7 can be solved. The stress due to the difference can be reduced from the central part. Thereby, it is possible to solve the problem that a local force is applied to the solder balls and the projections during lamination, or the solar cell element is cracked due to the warpage of the solar cell.
[0027]
Further, although the output extraction portion of the back electrode described with reference to the drawings is configured in a linear shape, it may be configured in a curved shape. Further, in each of the drawings, the output extraction portion 6 is described as being formed over substantially the entire length of the semiconductor substrate 1. However, the output extraction portion 6 can be formed only at a position where welding to the inner lead 8 is to be performed. .
[0028]
In the invention according to claim 8, using the above-described solar cell element, the front electrode 4 and the output extraction portion 6 of the back electrode of the adjacent solar cell element are connected by the inner lead. In order to obtain a desired output, a large number of solar cell elements are arranged in series and parallel between a translucent panel such as glass and a back surface protection material such as a film containing a steel plate on the back surface. Laminate with a transparent filler 11 such as EVA (ethylene-vinyl acetate copolymer). In this case, the occurrence of solder balls and protrusions at the electrode portions is reduced as much as possible, and the stress concentration at the ends of the solar cell element is also reduced.
[0029]
The present invention is not limited to the above embodiment, and many modifications and changes can be made within the scope of the present invention. For example, the shapes and the protruding directions of the plurality of protrusions may be different.
[0030]
【The invention's effect】
As described above, according to the solar cell element of the first aspect, the output portion of the back electrode formed on the back side of the semiconductor substrate is provided with the protrusion, and the length of the protrusion located at the end is Since the inner lead is formed shorter than the length of the protruding part located in the center part, when the inner lead is placed on the output extraction part of the back electrode and heat welded with a soldering iron or hot air, Excess solder flows to the protruding part, and it is possible to minimize the formation of solder balls and protrusions due to the excess solder aggregating on the periphery of the inner lead and cracking of the solar cell element in the subsequent process And the stress generated due to the difference in thermal expansion coefficient can be reduced at the end of the solar cell element at the end rather than at the center, and it is possible to prevent the occurrence of a crack starting point on the end face of the solar cell element, and Reduces the occurrence of cracks Kill.
[0031]
Further, in the solar cell module according to the eighth aspect, since the solar cell element having the protruding portion provided at the output extraction portion of the back electrode formed on the back surface side of the semiconductor substrate is used, when the inner lead is thermally welded, the output is reduced. Excess solder on the take-out part flows to the protruding part, which can minimize the formation of solder balls and protrusions due to the excess solder agglomerating on the periphery of the inner lead. It is possible to prevent the solar cell element from being cracked due to the protrusions, and also to prevent the solar cell element from being cracked because the occurrence of the crack starting point at the end face of the solar cell element is reduced. Even if the solar cell element is sealed between the translucent panel and the back surface protective material, the problem of cell breakage does not occur.
[Brief description of the drawings]
FIG. 1 is a diagram showing a back surface structure of a solar cell element according to the present invention.
FIG. 2 is a diagram showing another back surface structure of the solar cell element according to the present invention.
FIG. 3 is a diagram showing another back surface structure of the solar cell element according to the present invention.
FIG. 4 is a view for explaining a conventional solar cell element.
FIG. 5 is a diagram for explaining a connection state of a conventional solar cell element.
FIG. 6 is a view for explaining the structure of a conventional solar cell module.
FIG. 7 is a view for explaining the structure of a conventional solar cell module.
FIG. 8 is a diagram showing a surface electrode portion of a conventional solar cell element.
FIG. 9 is a diagram showing a back electrode portion of a conventional solar cell element.
FIG. 10 is a diagram showing another back electrode portion of a conventional solar cell element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Diffusion layer, 3 ... Anti-reflection film, 4 ... Surface electrode, 5 ... Current collection part, 6 ... Output extraction part, 7 ... Sun Battery element, 8: inner lead, 9: translucent panel, 10: back surface protection member, 11: filler, 12: frame member, 13: protrusion, 14. ..Hole, 15: Solar cell module, 16: Busbar part, 17: Finger electrode

Claims (8)

半導体接合部を有する半導体基板の一主面側に表面電極を形成するとともに、他の主面側に第一の金属による集電部と、この第一の金属よりも半田濡れ性のよい第二の金属による出力取出部とから成る裏面電極を形成した太陽電池素子において、前記出力取出部に突出部を設けるとともに、前記半導体基板の端部に位置する突出部の長さを中央部に位置する突出部の長さよりも短くしたことを特徴とする太陽電池素子。A surface electrode is formed on one main surface side of a semiconductor substrate having a semiconductor bonding portion, and a current collector made of a first metal on the other main surface side, and a second metal having better solder wettability than the first metal. In the solar cell element having the back electrode formed of the metal output extraction portion, the output extraction portion is provided with a projection, and the length of the projection located at the end of the semiconductor substrate is located at the center. A solar cell element characterized in that the length is shorter than the length of the protrusion. 前記出力取出部を帯状に形成し、かつ長手方向の少なくとも一方側に前記集電部に向かって突出する複数の突出部を設けたことを特徴とする請求項１に記載の太陽電池素子。2. The solar cell element according to claim 1, wherein the output extraction portion is formed in a belt shape, and a plurality of projections projecting toward the current collector are provided on at least one side in a longitudinal direction. 3. 前記出力取出部の突出部を前記集電部上もしくはその一部が前記集電部と重なるように設けたことを特徴とする請求項１又は２に記載の太陽電池素子。3. The solar cell element according to claim 1, wherein the projecting portion of the output extracting portion is provided so that the projecting portion or a part of the projecting portion overlaps the current collecting portion. 4. 前記出力取出部の突出部以外の領域は全面もしくは部分的に前記半導体基板と接していることを特徴とする請求項１ないし３のいずれかに記載の太陽電池素子。4. The solar cell element according to claim 1, wherein a region other than the projecting portion of the output extraction portion is entirely or partially in contact with the semiconductor substrate. 5. 前記出力取出部を帯状に形成し、かつ長手方向において島状に分断して形成したことを特徴とする請求項１ないし４のいずれかに記載の太陽電池素子。The solar cell element according to any one of claims 1 to 4, wherein the output extraction portion is formed in a band shape and is divided into island shapes in a longitudinal direction. 前記第一の金属がアルミニウムを主成分とすることを特徴とする請求項１ないし５のいずれかに記載の太陽電池素子。The solar cell element according to claim 1, wherein the first metal contains aluminum as a main component. 前記第二の金属が銀を主成分とすることを特徴とする請求項１ないし６のいずれかに記載の太陽電池素子。The solar cell element according to any one of claims 1 to 6, wherein the second metal has silver as a main component. 請求項１ないし７のいずれかに記載の太陽電池素子の表面電極と隣接する太陽電池素子の裏面電極の出力取出部とをインナーリードで接続してなる太陽電池モジュール。A solar cell module comprising a front electrode of the solar cell element according to any one of claims 1 to 7 and an output extraction portion of a rear electrode of the adjacent solar cell element connected by an inner lead.
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