JP2004179560A

JP2004179560A - Integrated thin-film photovoltaic device

Info

Publication number: JP2004179560A
Application number: JP2002346580A
Authority: JP
Inventors: Hisashi Higuchi; 永樋口
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-11-28
Filing date: 2002-11-28
Publication date: 2004-06-24

Abstract

<P>PROBLEM TO BE SOLVED: To realize a miniaturized device by reducing a light transmission loss, preventing an output drop and decreasing its thickness. <P>SOLUTION: An integrated thin-film photovoltaic device 1 of a mechanical stack type includes a first integrated thin-film photovoltaic element having a plurality of unit cells connected in series on one major surface of a first light transmitting substrate 10 and second integrated thin-film photovoltaic element having a plurality of unit cells connected in series on one major surface of a first substrate 60 having a conductive front surface. The first and second photovoltaic elements are arranged to be opposed to each other so that the other major surfaces of both the substrate 10, 60 are positioned outside. When the major surfaces of both the substrates 10, 60 are viewed in plane, the series-connection direction of the unit cells of the first photovoltaic element 110 is crossed by (optimumly, is made perpendicular to) the series-connection direction of the unit cells of the second photovoltaic element 160. Consequently, light currents flowing through cells of the second photovoltaic element become nearly equal, the light currents flowing through the cells can be efficiently connected in series, thus improving a conversion efficiency. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、２つの基板に形成された光起電力素子を、両基板が外側に配置されるように互いに対向させ、電気出力を素子毎に別々に取り出すことのできるメカニカル・スタック型の集積型薄膜光起電力装置に関し、特に、２つの集積型光起電力素子における集積化の方向と、２つの集積型光起電力素子の出力取り出し部の構造に関する。
【０００２】
【従来の技術】
薄膜太陽電池は高変換効率化と大面積化と低コスト化を目指した開発が活発である。この中で、太陽光エネルギー分布を有効に利用するために禁制帯幅の異なる複数の半導体接合を積み重ねた積層型の薄膜太陽電池の開発が活発に行われている。
【０００３】
従来例１として、光起電力素子群から成る２種類の基体を接着剤で機械的に貼り合わせ、電気出力を別々に取り出すメカニカル・スタック型の薄膜太陽電池モジュールが知られている（特許文献１を参照）。この薄膜太陽電池の断面模式図を図６と図７に示す。
【０００４】
この薄膜太陽電池モジュールは、第１の半導体からなる光起電力領域３１、３２、．．．．、と両側に透明電極２１、２２、．．．．、と４１、４２、．．．．、とを有し、分離形成された複数の直列接続ユニットセル１１１、１１２、．．．．、を備えた第１のガラス基板１０と、第１の半導体より狭いバンドギャップを持つ第２の半導体からなる光起電力領域８１、８２、．．．．、と、反基板側に透明電極９１、９２、．．．．、と基板側に導電層７１、７２、．．．．、とを有し、分離形成された直列接続ユニットセル１６１、１６２、．．．．、を備えた第２のガラス基板６０とが、両基板を外側にして対向させた状態で位置して互いにガラスにより気密に連結され、両基板上のユニットセル間の空間１５０は外部より遮断されている。上記特許文献１の実施形態において、第１の半導体としてアモルファスシリコンのＰＩＮ接合が、第２の半導体としてアモルファスシリコン・ゲルマニュームのＰＩＮ接合が記載されている。この構成により、バンドギャップの広い第１の半導体からなるセル側から入射した光はそのセルで吸収され接合により光電流が発生するが、吸収されない光は対向するバンドギャップの狭い第２の半導体からなるセルにて吸収され、再び光電流を発生するので、入射光の利用効率が向上するとしている。
【０００５】
図６は２枚の直列型太陽電池よりそれぞれ出力を独立に取り出すタイプである。これによれば、第１の半導体に対しての直列数と第２の半導体に対しての直列数とは等しく、２枚の直列型太陽電池におけるそれぞれの光起電力領域と、それぞれの直列接続用分離溝５１、５２、．．．．、と１０１、１０２、．．．．、とは入射光に対し一致して（重なって）おり、それぞれ異なった出力電圧であり、それぞれに出力の取り出し部があり、リード線が接続されている。
【０００６】
また図７に示すように、２枚のそれぞれの直列型太陽電池の両端を接続するために、第１の半導体に対しては５直列とし、第２の半導体に対しては６直列とし、両端の最適動作電圧がほぼ等しくなるようにして、それぞれの出力の取り出し部とリード線が直接接続されている。
【０００７】
従来例２として、メカニカル・スタック型の薄膜太陽電池モジュールが知られている（特許文献２を参照）。このタンデム太陽電池モジュールは、多結晶シリコンから成り大面積の下側の第１太陽電池サブモジュール、光カプラとして作用する透明な絶縁性中間層、水素添加非晶質シリコンから成り大面積で透明な上側の第２太陽電池サブモジュール、両方のサブモジュールの互いに無関係な電気接触部を備えることを特徴としている。また、多結晶シリコンとして、バルク単結晶シリコン以外にシリコン材料が基板上に析出した後再結晶処理例えばアニーリングにより多結晶構造となった薄膜太陽電池モジュールが好適としている。また、光カプラは入射光を吸収も反射もしない電気絶縁性としている。さらに、第１サブモジュールと第２サブモジュールとは等しい幅のストライブ型構造であることを特徴としている。
【０００８】
また、全モジュールを１つの枠に組み込み、全体で少なくとも４個の電気接触を通して各サブモジュールで発生した光電流が互に無関係に引き出されるとしている。
【０００９】
従来例３として、一つの基板上に禁制帯幅の異なる複数の半導体接合を積み重ねた積層型で、光学的・電気的に直列接続された二端子型タンデム構造である集積化されたタンデム型薄膜光起電力装置が知られている（特許文献３を参照）。
透明基板上に順次に積層された透明電極層、少なくとも１の非晶質シリコン系薄膜光起電力ユニット層、少なくとも１の結晶質シリコン系薄膜光起電力ユニット層、および裏面電極層が複数のタンデム型光起電力セルを形成するように実質的に直線状で互いに平行な複数の分離溝によって分離されていて、かつそれらの複数のセルは前記分離溝に平行な複数の接続用溝を介して互いに電気的に直列接続されていることを特徴とする。
【００１０】
これは、複数のタンデム型光起電力セルを形成するように実質的に直線状で互いに平行な複数の分離溝によって分離され、それらの複数のセルは前期分離溝によって分離され、さらに、それらの複数セルは前期分離溝に平行な複数の接続用溝を介して互いに電気的に直列接続されているものであり、一枚の基板上で集積化されている。基板が一枚のこの集積型薄膜光起電力装置では、基板の裏面電極側にバックシートなどが封止樹脂にて接着され、耐環境特性への配慮がなされている。
【００１１】
【特許文献１】
特公平５−２７２７８号公報
【特許文献２】
特開平１−６８９７７号公報
【特許文献３】
特開平１１−１８６５８３号公報
【００１２】
【発明が解決しようとする課題】
しかしながら、上述した従来例１の図６に示す構造では、２枚の直列型太陽電池の光起電力領域３１、３２、．．．．、と８１、８２、．．．．、および直列接続用分離溝５１、５２、．．．．、と１０１、１０２、．．．．、とは入射光に対して一致して（重なって）おり、２枚の直列型太陽電池の各ユニット（ユニットセル）に於ける光電流はほぼ一致し効率よく各ユニットの光電流を直列接続できるが、基板端部で出力電圧が異なるためそれぞれに独立した出力取り出し部（リード線など）が２枚の基板の両端にそれぞれ必要である。このため、これらの出力取り出し部がかさばってしまい、２枚のガラス基板間のギャップ（密接層）を狭くできないという問題や絶縁性に対する配慮と注意が必要であった。そして、このギャップが大きいため、貼り合せるための透明樹脂の使用量が増えてコスト高になったり、光の透過損失が増えて第二の直列型太陽電池の出力低下を生じたり、貼り合わせたメカニカル・スタック型太陽電池モジュールの厚みが増して小型化を妨げたりしていた。
【００１３】
また、従来例１の図７にしめす構造では、図より明らかなように、２枚の直列型太陽電池の光起電力領域３１、３２、．．．．、と８１、８２、．．．．、および直列接続用分離溝５１、５２、．．．．、と１０１、１０２、．．．．、とは入射光に対して一致して（重なって）おらず、第二の直列型太陽電池の各ユニットには、第一の直列型太陽電池の分離溝の影響（光の影となる悪影響）を受けるユニットと受けないユニットが存在し、第二の直列型太陽電池の各ユニットにおける光電流は異なってしまい、直列接続すると分離溝の影響を受けた小さい光電流のユニットに律速された光電流しか流れないという変換効率低下の問題を引き起こしていた。
【００１４】
さらに、基板端部で出力電圧が同じであるため出力リード線を接触・接続して取り出せるが、２枚の同じ基板端部よりリードを取り出しているため、これらのリード部がかさばってしまい、２枚のガラス基板間のギャップを狭くできないという問題があった。そしてギャップが大きいため、貼り合せるための透明樹脂の使用量が増えてコスト高になったり、光の透過損失が増えて第二の直列型太陽電池の出力低下を生じたり、貼り合わせたメカニカル・スタック型太陽電池モジュールの厚みが増して小型化を妨げたりしていた。
【００１５】
上述した従来例２の場合は、第１サブモジュールと第２サブモジュールとは等しい幅のストライブ型構造であり、全モジュールを１つの枠に組み込み、全体で少なくとも４個の電気接触を通して各サブモジュールで発生した光電流が互に無関係に引き出されるようにするとしており、前記従来例１の図６のケースと同じ問題があった。
【００１６】
上述した従来例３の場合は、一つの基板上で第１と第２の光起電力セルが直列接続された薄膜二端子型タンデム構造の光起電力装置であるため、第１の光起電力セルで発生する光電流と第２の光起電力セルで発生する光電流とが等しく、且つこれらの光電流が２つの起電力セルそれぞれの最適動作点でなければ高い変換効率が得られない。例えば、従来例３では第１のセルは非晶質であり光劣化するが第２のセルは結晶質であり光劣化しない。第１と第２の光起電力セルが直列接続されているためこれらの電流は回路的に等しくなければならず、第１セルの光劣化の影響を第２のセルも受けてしまい、ともに光電流が低下するという問題があった。また、基板の裏面電極側にバックシートなどが封止樹脂にて接着されていたが、薄くて強度の無いバックシートだけでは太陽電池モジュールの取り付け工事などで傷をつけ易く取り扱いに注意が必要であった。
【００１７】
本発明は斯かる事情に鑑みてなされたものであり、メカニカル・スタック型の集積型薄膜光起電力装置とすることにより、第１の光起電力セルと第２の光起電力セルとの光電流の律速要因を無くして変換効率の低下を無くすとともに、２枚のガラス基板間のギャップ（密接層）を狭くし、貼り合せるための透明樹脂層の使用量を減らしてコストを削減し、光の透過損失を減らして出力低下を防ぎ、厚みを薄くして装置の小型化を図ることを目的とする。また、第１の集積化された複数の薄膜光起電力ユニットセルからの透過光が第２の集積化された複数の薄膜光起電力ユニットセルにそれぞれ等しく照射されるように図ることである。また、出力取り出し部のリード接続を簡素にすることである。さらに、複数の薄膜光起電力装置を平面的に接続し拡大することを目的とする。そして、バックシートを無くし、低コスト化が可能で耐環境性に優れそして強度に優れた第２の基板による薄膜光起電力素子の保護をも目的とする。
【００１８】
【課題を解決するための手段】
上記目的を達成するために、本発明の集積型薄膜光起電力装置は、透光性を有する第１の基板の一主面上に、複数のユニットセルが直列接続して成る第１の集積型薄膜光起電力素子と、表面が導電性を有する第２の基板の一主面上に複数のユニットセルが直列接続して成る第２の集積型薄膜光起電力素子とを、前記両基板の他主面が外側に位置するように互いに対向させて成るメカニカル・スタック型の集積型薄膜光起電力装置であって、前記両基板の主面を平面視したときに、前記第１の集積型薄膜光起電力素子のユニットセルの直列接続方向と、前記第２の集積型薄膜光起電力素子のユニットセルの直列接続方向とが交叉していることを特徴とする。
【００１９】
また、前記集積型薄膜光起電力装置において、前記両基板の主面を平面視したときに、前記第１の集積型薄膜光起電力素子のユニットセルの直列接続方向と、前記第２の集積型薄膜光起電力素子のユニットセルの直列接続方向とが直交しているとともに、前記両基板の一主面には、前記両基板の主面を平面視したときに、互いに重ならない出力取り出し部があることを特徴とする。
【００２０】
また、前記第１の集積型薄膜光起電力素子と前記第２の集積型薄膜光起電力素子との間に、透光性樹脂層もしくは断熱用気体層を含む密接層を介在させたことを特徴とする。
【００２１】
また、前記両基板の一主面側の外周領域を粗面化したことを特徴とすることを特徴とする集積型薄膜光起電力装置。
【００２２】
また、前記出力取り出し部どうしを互いに電気的に接続したことを特徴とする。
【００２３】
また、前記密接層の厚みが０．０１ｍｍ〜２０ｍｍの範囲にあることを特徴とする。
【００２４】
また、前記第１の集積型薄膜光起電力素子の表面、前記第２の集積型薄膜光起電力素子の表面、前記第１の基板の一主面、及び前記第２の基板の一主面において、少なくとも一つが凹凸状を成す光閉じ込め構造を有することを特徴とする。
【００２５】
また、少なくとも一部を透明にしてシースルー構造にしたことを特徴とする。
【００２６】
また、前記第１及び第２の集積型薄膜光起電力素子の外周部を保護枠で固定したことを特徴とする。
【００２７】
【発明の実施の形態】
以下、本発明に係る実施形態を図面に基づいて詳細に説明する。本発明の集積型薄膜光起電力装置の断面模式図を図１，図２、及び図３，図４、並びに図５に示す。これらの図において矢印Ｌは光の入射方向を示す。
【００２８】
まず、本発明に係る第１の実施形態を図面に基づいて詳細に説明する。図１と図２は同一の集積型薄膜光起電力装置（それぞれの光起電力装置は、ユニットセルの複数が直列接続して成る）の断面模式図であるが、９０度異なった（基板主面の平面視において、ユニットセルの直列方向が互いに直交する）断面模式図である。すなわち、図１に示すＡ−Ａ´断面が図２である。
【００２９】
図１及び図２に示すように、本発明の集積型薄膜光起電力装置は、透光性を有する第１の基板１０の一主面上に、複数のユニットセルが直列接続して成る第１の集積型薄膜光起電力素子と、表面が導電性を有する第２の基板６０の一主面上に複数のユニットセルが直列接続して成る第２の集積型薄膜光起電力素子とを、両基板１０，６０の他主面が外側に位置するように互いに対向させて成るメカニカル・スタック型の集積型薄膜光起電力装置であって、両基板１０，６０の主面を平面視したときに、前記第１の集積型薄膜光起電力素子のユニットセルの直列接続方向と、前記第２の集積型薄膜光起電力素子のユニットセルの直列接続方向とが交叉（最適には直交）している。そして特に、両基板１０，６０の一主面には、両基板１０，６０の主面を平面視したときに、互いに重ならない出力取り出し部があることを特徴とする。
【００３０】
具体的には、集積型薄膜光起電力装置１は、第１の基板１０を備えた第１の集積型薄膜光電素子（ユニットセル１１１、１１２、．．．．、）と、第２の基板６０を備えた第２の集積型薄膜光電素子１６Ｘ（Ｘ＝１、２、．．．．）が、両基板１０，６０を外側にして対向して配置されたメカニカル・スタック型の集積型薄膜光起電力装置１であって、第１の集積型薄膜光電素子（ユニットセル１１１、１１２、．．．．）は、透光性基板１０上に順次、第１の透光性導電層２１、２２、．．．．、第１の薄膜光起電力層３１、３２、．．．．、及び第２の透光性導電層４１、４２、．．．．、からなる。第２の集積型薄膜光電素子１６Ｘ（Ｘ＝１、２、．．．．）は、第２の基板６０である絶縁層を備えた導電性基板もしくは絶縁性基板上に順次、導電層７Ｘ、第２の薄膜光起電力層８Ｘ、及び第３の透光性導電層９Ｘ（Ｘ＝１、２、．．．．）からなる。そして、両素子間の密接層が透光性樹脂層１５０もしくは断熱用気体層を含む密接層１５０からなる。第１の集積型薄膜光電素子（ユニットセル１１１、１１２、．．．．）の間には、分離溝（直列接続領域）５１、５２、．．．．、があり、第２の集積型薄膜光電素子（ユニットセル１６１、１６２、．．．．）の間には、分離溝（直列接続領域）１０１、１０２、．．．．、がある。
【００３１】
また、第１の基板端上には、出力取り出し部１２１、１２２があり、リード線１３１、１３２が外部へと接続されている。
【００３２】
第１の薄膜光起電力層３１、３２、．．．．、は、例えば、第１の一導電型シリコン系半導体層、実質的に真性である非単結晶シリコン系半導体層、第１の逆導電型シリコン系半導体層の積層から成る（図示せず）。また、第２の薄膜光起電力層８Ｘ（Ｘ＝１、２、．．．．）は、例えば、第２の一導電型シリコン系半導体層、実質的に真性である非単結晶シリコン系半導体層、第２の逆導電型シリコン系半導体層、の積層から成る（図示せず）。これらの薄膜半導体にはシリコン系以外に化合物半導体系や色素系などを用いても構わない。
【００３３】
図２は図１に記載したＡ−Ａ´断面の断面模式図である。図２の説明は図１と同様であり、説明を省略する。
【００３４】
そして本発明の実施例１では、図１及び図２に示すように、第１の基板の幅と第２の基板の幅はいずれも同じ幅である。
【００３５】
これらによれば、第１の集積型薄膜光起電力素子（ユニットセル１１１、１１２、．．．．、）の直列接続方向（集積化方向）と、前記第２の集積型薄膜光起電力素子１６１、１６２、．．．．の直列接続方向（集積化方向）とが直交を成すことにより、第２の集積型薄膜光電素子（ユニットセル１６１、１６２、．．．．、）は、第１の集積型薄膜光電素子１１１、１１２、．．．．、と分離溝５１、５２、．．．．、からの透過光の影響を均等に受光することができる。これにより、第２の集積型薄膜光起電力素子１６１、１６２、．．．．の各素子（ユニットセル）に於ける光電流はほぼ一致し効率よく各ユニットの光電流を直列接続できる。
【００３６】
また、図１の第１の集積型薄膜光起電力素子１１０の出力取り出し部１２１、１２２及びリード線１３１、１３２は、図２の図１の第２の集積型薄膜光起電力素子１６０の出力取り出し部１７１、１７２及びリード線１８１、１８２と９０度ずれた位置関係にあり、第１の基板１０の幅と第２の基板６０の幅が等しくても、これらが重なることは無い。従って、絶縁性に対する配慮と注意が不必要となり、２枚のガラス基板間のギャップ（密接層）が狭くできて、貼り合せるための透明樹脂の使用量が減ってコスト減になり、光の透過損失が減って第二の直列型太陽電池の出力低下を生じなくなり、貼り合わせたメカニカル・スタック型太陽電池モジュールの厚みが減って小型化を行うことが出来た。
【００３７】
また、本発明の第１及び／または第２の薄膜光起電力層に結晶質半導体層の結晶質柱状堆積による自生凹凸を設け、この透光性樹脂層からなる密接層１５０との凹凸構成により、光閉じ込め効果を高めることができる。この光閉じ込め効果の向上により、従来に比し変換効率の向上をもたらす。
【００３８】
また、本発明の集積型薄膜光起電力装置１によれば、第１の基板１０の表面（一主面）もしくは第１の透光性導電層２１、２２、．．．．、の表面が凹凸をなすことを特徴とする。これにより、積層構造の入射位置に凹凸面を得たことになり、光の選択入射・屈折そして吸収が特に第１の集積型薄膜光起電力装置でより活発となり、光閉じ込め効果のアップにより、変換効率の向上をもたらす。
【００３９】
また、本発明の集積型薄膜光起電力装置によれば、第２の基板６０もしくは導電層７１、７２、．．．．、の表面が凹凸をなすことを特徴とする。これにより、短波長光より光侵入が深い長波長光に対して、第１の凹凸がより光透過性となり、第２の凹凸がより光反射性となり、長波長光の光閉じ込め効果が増してより高い変換効率の向上をもたらす。
【００４０】
また、第１と第２の集積型薄膜光電素子間に第１と第２の薄膜光起電力層と屈折率差の大きい透光性樹脂からなる密接層１５０を設けることにより、第１の集積型薄膜光起電力素子への光反射が大きくなり、第１の集積型薄膜光起電力素子の変換効率を向上できる。すなわち、密接層１５０が主に断熱用気体層の場合、屈折率差及び断熱性も大きくより効果的である。また断熱用気体層を減圧気体層もしくは真空層にすることにより、屈折率差及び断熱性も大きくより効果的である。密接層１５０が断熱用気体層と透光性樹脂層との並層の場合、断熱用気体層による前記効果とともに、透光性樹脂層により両素子間の隙間を固定化できて薄膜光起電力装置の機械的安定性を保持できる。特に、非集積セルの場合外周を固定化し、集積セルの場合分離溝を固定化すると効率への悪影響が無く好都合である。密接層１５０が気体と透光性樹脂材の混合層の場合、全面において隙間の固定が出来て機械的強度を備えることができ、気体と透光性樹脂材との繰り返しを光の波長オーダーとすることにより光の反射率を高めることができる。
【００４１】
また、図１において、第１の基板１０の出力取り出し部１２１、及びこれと対向する第２の基板の対向部である領域１４１において、これらの下地である透光性基板１０と第２の基板６０上における第１の透光性導電層２１と第２の導電層７Ｘが無い領域（図示せず）を第１と第２の基板の一主面の外周部に設け、さらにこれらの領域（下地基板のはみ出し領域）の表面を粗面化することにより、出力取り出し部とリード線取り付け部を樹脂封止する上でより強固な密着性が確保できて、耐環境性・耐湿性にすぐれた封止となる。他方の基板端部についても同様である。こうして、第１の基板１０の一主面における外周部と第２の基板６０の一主面における外周部において、薄膜を少なくとも取り除き、さらに基板を凹凸化することにより、膜剥離が無く接着面積も増えて耐環境性・耐湿性にすぐれた封止ができる。
【００４２】
また、本発明の集積型薄膜光起電力装置１における密接層の厚みを０．０１ｍｍから２０ｍｍの範囲とすることを特徴とする。なぜなら、密接層の厚みが０．０１μｍ以下であれば第１の集積型薄膜光電素子と第２の集積型薄膜光電素子の絶縁性に問題が生じる恐れがあり、２０ｍｍ以上であれば本発明の集積型薄膜光起電力装置１の厚みが厚くなりモジュールの小型化が実現できなくなってしまうからである。
【００４３】
また、図１において、第１の集積型薄膜光起電力素子１１０の出力取り出し部１２１、１２２及びリード線１３１、１３２は、図２の第２の集積型薄膜光起電力素子１６０の出力取り出し部１７１、１７２及びリード線１８１、１８２とは独立して出力を取り出すことができるので、それぞれを最適動作点で動作させることができるので、高い変換効率が得られる。
【００４４】
また、裏面電極側に従来のバックシートなどより厚くて強度が強く耐環境性に優れた第２の基板を設けたことにより、太陽電池モジュールの取り付け工事などで傷をつける危険や取り扱い上の注意がほとんど無くなり、信頼性の高い太陽電池モジュールが提供できる。
【００４５】
次に本発明に係る第２の実施形態を図面に基づいて詳細に説明する。図３と図４は同一の集積型薄膜光起電力装置の断面模式図であるが、９０度異なった断面模式図である。すなわち、図３に示すＡ−Ａ´断面が図４である。
【００４６】
前記第１の実施形態と第２の実施形態と違いは、図３及び図４に示すように、第１の基板１０の幅と第２の基板６０の幅が異なり、基板端部に出力取り出し部とリード線を有する基板側の幅を大きくしていることである。
【００４７】
これにより、出力取り出し部からのリード線などの接続を容易にしたことを特徴としている。すなわち、第１の基板と第２の基板とを密接層を介した貼り合せ後に、出力取り出し部からのリード線などの接続作業を妨げ無しで容易にできる。
【００４８】
次に本発明に係る第３の実施形態を図面に基づいて詳細に説明する。図５は第２の実施形態の集積型薄膜光起電力装置を複数個接続した形態を示す断面模式図である。この断面模式図では横方向に３つの集積型薄膜光起電力装置を平面的に接続した場合を図示しているが、より一般的には複数個の集積型薄膜光起電力装置を平面的に接続したものである。縦方向にも複数個の集積型薄膜光起電力装置を平面的に接続したものである。
【００４９】
本実施形態の集積型薄膜光起電力装置１は、横方向に第１の集積型薄膜光起電力装置２１、第２の集積型薄膜光起電力装置２２、．．．．、から成る。ここで、第１の集積型薄膜光起電力装置２１は、第１の基板１１、第１の集積型薄膜光電素子１１１、第２の基板６１、第２の集積型薄膜光電素子１６１、と密接層から構成されている。第２の集積型薄膜光起電力装置２２、．．．．、も同様である。この図５に示すように、両端の最終の出力取り出し部１２１、１２２とリード線１３１、１３２を除けば、出力取り出し部を互い違いに弾性もしくは溶接の導電体等にてほぼ直接接続できる構造としており、横方向に第１の基板１１の端面と第１の基板１２の端面、及び第２の基板６１の端面と第２の基板６２の端面とを直接接着もしくは緩衝スペーサを介して接着することにより、横方向に集積型薄膜光起電力装置を拡大することができる。同様に、縦方向にも集積型薄膜光起電力装置を拡大することができる。こうして、平面状に機械的に拡大化された集積型薄膜光起電力装置１を作ることができる。
【００５０】
こうして、均一性に優れ入手しやすい小型のプラズマＣＶＤ装置などを用いて、小さい基板サイズで集積型薄膜光起電力装置を多数製作し、これらを平面状に機械的に拡大化することにより、大きなサイズの集積型薄膜光起電力装置１を作ることができる。
【００５１】
また、本発明の集積型薄膜光起電力装置によれば、非晶質シリコン系半導体層２２、結晶質シリコン系半導体層７２が、化学気相成長法により連続堆積することなくそれぞれ独自の製膜条件で堆積されることを特徴とする。
【００５２】
また、第２の基板６０を透光性基板とし、第２の集積型薄膜光起電力素子の導電層７１、７２、．．．．、の一部を均等にリジェクトすることにより外光を透過させるシースルー型の集積型薄膜光起電力装置１を得ることができる。
【００５３】
また、該集積型薄膜光起電力装置１の端部外周が少なくとも保護枠で固定されることにより、本発明の集積型薄膜光起電力装置１の機械的強度を上げることができる。
【００５４】
【実施例】
以下、本発明をより具体的に示す実施例１〜４で説明する。
＜実施例１＞
図１、図２において、１は集積型薄膜光起電力装置である。１０は透光性基板であり、本実施例では透光性基板として、両面が平坦な青板ガラス（厚み１．８ｍｍ）を用いた。他の透光性基板として、白板ガラスなど各種ガラス、サファイアなどの透明無機質基板、ポリカーボネートなどの透明有機樹脂基板などを用いてもよい。２１、２２、．．．．は、第１の透光性導電膜で、本実施例ではスパッタ法で堆積したＩＴＯ膜を用いたが、熱ＣＶＤ法やスプレー法などによるＳｎＯ２膜などを用いてもよい。以下、分離溝５１、５２、．．．．、の形成は随時レーザー照射にて形成したが、フォトプロセスで形成しても構わない。他の透光性導電膜として、スパッタ法などで堆積したＳｎＯ２膜やＺｎＯ（不純物ドープ）膜などを用いてもよく、これらの透光性導電膜を積層して用いてもよい。３１、３２、．．．．は、ＰＩＮ接合を有する非晶質シリコン系半導体膜であり、水素化アモルファスシリコン系の膜を用い、Ｐ型半導体膜とＩ型半導体膜とＮ型半導体膜の積層によるＰＩＮ接合半導体とし、本実施例ではプラズマＣＶＤ法で堆積したが、触媒ＣＶＤ法などで堆積してもよい。本実施例では第１の透光性導電膜側にＰ型半導体膜を設けたＰＩＮ接合としたが、逆接合のＮＩＰ接合でも構わない。また、Ｉ型半導体膜が非晶質であれば、Ｐ型半導体膜とＮ型半導体膜もしくはいずれかが微結晶でも構わない。また、水素化アモルファスシリコン合金系の膜でも構わない。例えば、光入射側のＰ膜は水素化アモルファスシリコンカーバイドが透光性を高めて光の侵入ロスが少なくより好ましい。
【００５５】
４１、４２、．．．．は、第２の透光性導電膜であり、ＩＴＯ膜をスパッタ法で堆積した。他の第２の透光性導電膜として、ＺｎＯ、ＳｎＯ２：Ｆなどを用いてもよく、これらの積層膜でもよい。また、この上にＡｇ膜を堆積して櫛型などの電極パターンを形成した集電極を有してもよい。
【００５６】
６０は絶縁層を備えた導電性基板もしくは絶縁性基板であり、これに導電層７１、７２、．．．．、第２の薄膜光起電力層８１、８２、．．．．、及び第３の透光性導電層９１、９２、．．．．であり、本実施例では絶縁性基板である青板ガラス１．８ｍｍｔを用いた。他の基板として、各種ガラスなどの無機質基板、ポリカーボネートなどの有機樹脂基板、またアルミ基板やステンレス基板などの導電性基板を用いてもよい。
【００５７】
７１、７２、．．．．は光反射性導電膜であり、本実施例ではＴｉ／Ａｇ／Ｔｉの積層膜を用いた。基板側のＴｉ膜は密着性促進のためであり、Ａｇ膜上のＴｉ膜は半導体膜中へのＡｇ拡散抑止のためである。Ａｇ膜は、高光反射性を有し、高変換効率が得られやすい。他の材料構成として、Ｔｉ／Ａｇ：Ａｌ合金／ＺｎＯ：Ａｌなどでも構わない。
【００５８】
８１、８２、．．．．は、ＰＩＮ接合を有する結晶質シリコン系半導体膜であり、プラズマＣＶＤ法や触媒ＣＶＤ法などで堆積して得られる比較的高い結晶化率を有する微結晶シリコン系の膜を用い、Ｐ型半導体膜とＩ型半導体膜とＮ型半導体膜の積層によるＰＩＮ接合半導体とした。Ｉ型半導体膜が微結晶であれば、Ｐ型半導体膜とＮ型半導体膜もしくはいずれかが非晶質でも構わない。本実施例では前記光反射性導電膜付きガラス基板上にプラズマＣＶＤ法によりＮＩＰ型半導体膜をそれぞれ連続して堆積した。光反射性導電膜側にＮ型半導体膜を設けたＮＩＰ接合としたが、逆接合のＰＩＮ接合でも構わない。また、微結晶シリコン合金系の膜でも構わない。本実施例ではプラズマＣＶＤ法を用いた。９１、９２、．．．．は、第３の透光性導電膜で、本実施例ではＩＴＯ膜をスパッタ法で堆積した。他の第２の透光性導電膜として、ＺｎＯ：Ａｌ、ＳｎＯ２：Ｆなどを用いてもよく、これらの積層膜でもよい。また、この上に前記同様の集電極を形成してもよい。
【００５９】
１５０は透光性樹脂であり、本実施例では透明封止樹脂のＥＶＡ（エチレン酢酸ビニル共重合樹脂）を用いた。ＥＶＡシートを両基体に挟み、これらを減圧し、加熱による樹脂の溶融、ＥＶＡの圧着・充填、熱硬化、一次冷却、大気圧への開放、二次冷却からなる工程によって集積型薄膜光電素子１を作製した。
また、集積型薄膜光電素子１の外枠として、断面がＵ字型であるアルミニウム材からなる保護枠を用いた。アルミニウムのほかにステンレスなどの金属材料やＦＴＰなどの硬質プラスチックが用いてもよい。
【００６０】
＜実施例２＞
図３、図４において、１は集積型薄膜光起電力装置である。１１は透光性基板であり、６０は絶縁層を備えた導電性基板もしくは絶縁性基板であり、これらの基板サイズが図３、図４に示すように、約１０ｍｍのはみ出し領域（重ならない領域）を有するように準備した。この後の工程は、前記実施例１と同様にとした。
【００６１】
【発明の効果】
本発明の集積型薄膜光起電力装置によれば、第１の集積型薄膜光起電力素子の直列接続方向（集積化方向）と、前記第２の集積型薄膜光起電力素子の直列接続方向（集積化方向）が交叉（最適には直交）を成すことにより、第２の集積型薄膜光電素子は、第１の集積型薄膜光電素子と分離溝からの透過光の影響を均等に受光することができる。これにより、第２の集積型薄膜光起電力素子の各素子（ユニット）に於ける光電流がほぼ一致し効率よく各ユニットの光電流を直列接続できるので変換効率が向上する。
【００６２】
また、請求項１及び２によれば、第１の集積型薄膜光起電力素子の出力取り出しと第２の集積型薄膜光起電力素子の出力取り出しとは独立して出力を取り出すことができるので、それぞれを最適動作点で動作させ高い変換効率が得られる。
そして、第１の集積型薄膜光起電力素子の出力取り出しと第２の集積型薄膜光起電力素子の出力取り出しとを直接接続して同じ電圧で出力を取り出すこともできるので、それぞれを最適動作点で動作させ高い変換効率が得られる。さらに、裏面電極側に従来のバックシートなどより厚くて強度が強く耐環境性に優れた第２の基板を設けることもできるので、太陽電池モジュールの取り付け工事などで傷をつける危険や取り扱い上の注意が無くなり、信頼性の高い太陽電池モジュールが提供できる。また、例えば、第１の基板の幅と第２の基板の幅が異なり、基板端部に出力取り出し部とリード線を有することにより、出力取り出し部からのリード線などの接続を容易にできる。すなわち、第１の基板と第２の基板とを密接層を介した貼り合せ後に、出力取り出し部からのリード線などの接続作業を障害物なしで行うことができる。さらに、横方向に複数個の集積型薄膜光起電力装置を段違いに交互に平面的に位置するように、リード線を用いることなく出力取り出し部を互い違いに弾性導電体等にて直接接続し、基板の端面とそれに対向させる基板の端面とを直接接着もしくはスペーサを介して接着することにより、平面状に機械的に拡大した集積型薄膜光起電力装置を作ることができる。これにより、均一性に優れ入手しやすい小型のプラズマＣＶＤ装置などにて小さいサイズの基板で集積型薄膜光起電力装置を複数個製作し、これらを平面状に機械的に拡大化することにより、大きなサイズの集積型薄膜光起電力装置を作製することができる。
【００６３】
また、特に請求項２によれば、第１の集積型薄膜光起電力素子の出力取り出し部及びリード線は、第２の集積型薄膜光起電力素子の出力取り出し部及びリード線と９０度ずれた位置にあり、第１の基板の幅と第２の基板の幅が等しくても、これらが重なることは無い。従って、絶縁が確実となり、２枚のガラス基板間のギャップ（密接層）が狭くでき、貼り合せるための透明樹脂の使用量が減ってコスト減になり、光の透過損失が減って第二の直列型太陽電池の出力低下を生じることがなく、貼り合わせたメカニカル・スタック型太陽電池モジュールの厚みが減って小型化ができる。
【００６４】
また、請求項３によれば、第１と第２の集積型薄膜光電素子間に第１と第２の薄膜光起電力層と屈折率差の大きい透光性樹脂からなる密接層を設けることにより、第１の集積型薄膜光起電力素子への光反射が大きくなり、第１の集積型薄膜光起電力素子の変換効率を向上できる。すなわち、このような密接層が主に断熱用気体層の場合、屈折率差及び断熱性も大きくより効果的である。また断熱用気体層を減圧気体層もしくは真空層にすることにより、屈折率差及び断熱性も大きくより効果的である。密接層が断熱用気体層と透光性樹脂層との並層の場合、断熱用気体層による前記効果とともに、透光性樹脂層により両素子間の隙間を固定化できて薄膜光起電力装置の機械的安定性を保持できる。特に、非集積セルの場合外周を固定化し、集積セルの場合分離溝を固定化すると効率への悪影響が無く好都合である。密接層が気体と透光性樹脂材の混合層の場合、全面において隙間の固定が出来て機械的強度を備えることができ、気体と透光性樹脂材との繰り返しを光の波長オーダーとすることにより光の反射率を高めることができる。
【００６５】
また、請求項４によれば、例えば、第１の基板の出力取り出し部、及びこれと対向する第２の基板の対向部である領域において、これらの下地である第１の透光性導電層と第２の導電層を取り除き、さらにこれらの下地である透光性基板と第２の基板における外周部の表面を粗面化することにより、出力取り出し部とリード線などを樹脂封止する上で、より強固な密着性が確保できて、耐環境性・耐湿性にすぐれた封止ができる。他方の基板端部についても同様である。こうして、第１の基板の外周部と第２の基板の外周部において、薄膜を取り除くことにより、さらには粗面化を行うことにより、耐環境性・耐湿性にすぐれた封止ができる。
【００６６】
また、請求項６によれば、密接層の厚みを０．０１ｍｍから２０ｍｍの範囲とし、この密接層の厚みを０．０１μｍ以上とすることにより第１の集積型薄膜光電素子と第２の集積型薄膜光電素子の絶縁が確実となり、２０ｍｍ以下とすることにより本発明の集積型薄膜光起電力装置の厚みが薄くできてモジュールの小型化が実現できる。
【００６７】
また、請求項７によれば、第１の透光性基板における表面もしくは第１の透光性導電層の表面が凹凸をなすことにより、積層構造の入射位置に凹凸面を得たことになり、光の選択入射・屈折そして吸収が特に第１の集積型薄膜光起電力装置でより活発となり、短波長光の光閉じ込め効果のアップにより、変換効率の向上をもたらすことができる。また、第２の絶縁性基板における表面もしくは導電層の表面が凹凸をなすことにより、短波長光より光侵入が深い長波長光に対してより光反射性となり、長波長光の光閉じ込め効果が増してより高い変換効率の向上をもたらすことができる。
【００６８】
また、請求項８によれば、例えば絶縁基板を透光性基板とし、第２の集積型薄膜光起電力素子における導電層の一部を均等に除去することにより、外光を透過させるシースルー型の集積型薄膜光起電力装置を得ることができる。
【００６９】
また、請求項９によれば、該集積型薄膜光起電力装置の端部外周が少なくとも保護枠で固定されることにより、本発明の集積型薄膜光起電力装置の機械的強度を上げることができる。
【図面の簡単な説明】
【図１】本発明に係る集積型薄膜光起電力装置の一実施形態を模式的に説明する断面図である。
【図２】本発明に係る集積型薄膜光起電力装置の一実施形態を模式的に説明する断面図である。
【図３】本発明に係る集積型薄膜光起電力装置の他の実施形態を模式的に説明する断面図である。
【図４】本発明に係る集積型薄膜光起電力装置の他の実施形態を模式的に説明する断面図である。
【図５】本発明に係る集積型薄膜光起電力装置を模式的に説明する断面図である。
【図６】従来の集積型薄膜光起電力装置の一例を説明する断面図である。
【図７】従来の集積型薄膜光起電力装置の一例を説明する断面図である。
【符号の説明】
１：集積型薄膜光起電力装置
１０、１１、１２：透光性基板（第１の基板）
２１、２２、．．．．：第１の透光性導電層
３１、３２、．．．．：第１の薄膜光起電力層
４１、４２、．．．．：第２の透光性導電層
５１、５２、．．．．：分離溝（直列接続領域）
６０、６１、６２：絶縁層を備えた導電性基板もしくは絶縁性基板（第２の基板）
７１、７２、．．．．：導電層
８１、８２、．．．．：第２の薄膜光起電力層
９１、９２、．．．．：第３の透光性導電層
１１０：第１の集積型薄膜光起電力素子
１２１、１２２、．．．．：出力取り出し部
１３１、１３２、．．．．：リード線
１５０：密接層
１６０：第２の集積型薄膜光起電力素子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mechanical stack type integrated type in which photovoltaic elements formed on two substrates are opposed to each other so that both substrates are arranged outside, and electrical output can be separately taken out for each element. The present invention relates to a thin-film photovoltaic device, and more particularly, to a direction of integration in two integrated photovoltaic devices and a structure of an output extraction portion of the two integrated photovoltaic devices.
[0002]
[Prior art]
Thin-film solar cells are being actively developed for higher conversion efficiency, larger area, and lower cost. Among them, in order to effectively utilize the solar energy distribution, a stacked thin-film solar cell in which a plurality of semiconductor junctions having different forbidden band widths are stacked has been actively developed.
[0003]
As a conventional example 1, there is known a mechanical stack type thin film solar cell module in which two types of substrates composed of a group of photovoltaic elements are mechanically bonded to each other with an adhesive, and electric outputs are separately taken out (Patent Document 1). See). FIGS. 6 and 7 show schematic sectional views of this thin-film solar cell.
[0004]
The thin-film solar cell module includes photovoltaic regions 31, 32,. . . . , And transparent electrodes 21, 22,. . . . , And 41, 42,. . . . , And a plurality of serially connected unit cells 111, 112,. . . . , And photovoltaic regions 81, 82,... Made of a second semiconductor having a band gap narrower than that of the first semiconductor. . . . , And the transparent electrodes 91, 92,. . . . , And conductive layers 71, 72,. . . . , And serially connected unit cells 161, 162,. . . . And the second glass substrate 60 having the two substrates facing each other with the two substrates facing outward and being air-tightly connected to each other by glass. The space 150 between the unit cells on both substrates is shut off from the outside. ing. In the embodiment of Patent Document 1, a PIN junction of amorphous silicon is described as a first semiconductor, and a PIN junction of amorphous silicon-germanium is described as a second semiconductor. With this configuration, light incident from the cell side including the first semiconductor having a wide band gap is absorbed by the cell and a photocurrent is generated by junction, but light not absorbed is transmitted from the opposing second semiconductor having a narrow band gap. Since the photocurrent is generated again by being absorbed in the cell, the utilization efficiency of the incident light is improved.
[0005]
FIG. 6 shows a type in which outputs are independently taken out of two series solar cells. According to this, the number of series with respect to the first semiconductor and the number of series with respect to the second semiconductor are equal, each photovoltaic region in the two series type solar cells, and each series connection. Separation grooves 51, 52,. . . . , And 101, 102,. . . . , Are coincident (overlap) with the incident light, have different output voltages, have output output portions, and are connected to lead wires.
[0006]
Also, as shown in FIG. 7, in order to connect both ends of each of the two series-type solar cells, five series are connected to the first semiconductor and six series are connected to the second semiconductor. Of the respective outputs are directly connected to the lead wires such that the optimum operating voltages are substantially equal to each other.
[0007]
As Conventional Example 2, a mechanical stack type thin-film solar cell module is known (see Patent Document 2). This tandem solar cell module is made of polycrystalline silicon and has a large-area lower first solar cell sub-module, a transparent insulating interlayer acting as an optical coupler, and a large-area transparent silicon made of hydrogenated amorphous silicon. The upper second solar cell sub-module is characterized by comprising unrelated electrical contacts of both sub-modules. Further, as the polycrystalline silicon, a thin film solar cell module in which a polycrystalline structure is formed by a recrystallization treatment, for example, annealing after a silicon material is deposited on a substrate in addition to bulk single crystal silicon is preferable. The optical coupler is made of an electrically insulating material that does not absorb or reflect incident light. Further, the first sub-module and the second sub-module are characterized by having a stripe type structure having the same width.
[0008]
Further, all the modules are incorporated in one frame, and the photocurrent generated in each sub-module is extracted independently of each other through at least four electrical contacts.
[0009]
As a third conventional example, an integrated tandem thin film having a two-terminal tandem structure in which a plurality of semiconductor junctions having different forbidden band widths are stacked on a single substrate and optically and electrically connected in series. A photovoltaic device is known (see Patent Document 3).
A transparent electrode layer sequentially laminated on a transparent substrate, at least one amorphous silicon-based thin-film photovoltaic unit layer, at least one crystalline silicon-based thin-film photovoltaic unit layer, and a back electrode layer comprising a plurality of tandems. Are separated by a plurality of substantially linear and parallel separation grooves so as to form a photovoltaic cell, and the plurality of cells are separated by a plurality of connection grooves parallel to the separation groove. It is characterized by being electrically connected in series to each other.
[0010]
It is separated by a plurality of substantially linear and parallel separation grooves to form a plurality of tandem photovoltaic cells, the cells being separated by the separation grooves, The plurality of cells are electrically connected to each other in series via a plurality of connection grooves parallel to the separation groove, and are integrated on one substrate. In this integrated type thin film photovoltaic device having a single substrate, a back sheet or the like is adhered to the back electrode side of the substrate with a sealing resin, and consideration is given to environmental resistance characteristics.
[0011]
[Patent Document 1]
Japanese Patent Publication No. 5-27278
[Patent Document 2]
JP-A-1-68997
[Patent Document 3]
JP-A-11-186585
[0012]
[Problems to be solved by the invention]
However, in the structure shown in FIG. 6 of Conventional Example 1 described above, the photovoltaic regions 31, 32,. . . . , And 81, 82,. . . . , And separation grooves 51, 52,. . . . , And 101, 102,. . . . And coincide with (overlap) the incident light, and the photocurrents in each unit (unit cell) of the two series-type solar cells are almost the same, and the photocurrents of the respective units are efficiently connected in series. However, since the output voltages are different at the ends of the substrates, independent output extraction portions (such as lead wires) are required at both ends of the two substrates. For this reason, these output take-out parts are bulky, and it has been necessary to pay attention to the problem that the gap (close layer) between the two glass substrates cannot be narrowed and the insulating property. And since this gap is large, the amount of the transparent resin used for bonding increases and the cost increases, or the transmission loss of light increases and the output of the second series solar cell decreases, or the bonding is performed. The thickness of the mechanical stack type solar cell module was increasing, which hindered miniaturization.
[0013]
Further, in the structure shown in FIG. 7 of Conventional Example 1, as is clear from the figure, the photovoltaic regions 31, 32,. . . . , And 81, 82,. . . . , And separation grooves 51, 52,. . . . , And 101, 102,. . . . , Do not coincide (overlap) with the incident light, and each unit of the second series-type solar cell is affected by the separation groove of the first series-type solar cell (the adverse effect of shadowing light). ) There is a unit that receives and a unit that does not receive, and the photocurrent in each unit of the second series solar cell differs, and when connected in series, the light that is limited by the unit of small photocurrent affected by the separation groove This causes a problem of lowering the conversion efficiency that only current flows.
[0014]
Further, since the output voltage is the same at the board end, the output lead wires can be brought into contact and connected to be taken out. However, since the leads are taken out from the same two board ends, these leads are bulky, There is a problem that the gap between the glass substrates cannot be narrowed. And because of the large gap, the amount of transparent resin used for bonding increases and the cost increases, the transmission loss of light increases and the output of the second series solar cell decreases, or the mechanical and The thickness of the stacked solar cell module has increased, which has hindered miniaturization.
[0015]
In the case of Conventional Example 2 described above, the first sub-module and the second sub-module are of a stripe type structure having the same width, all the modules are assembled in one frame, and each sub-module is connected through at least four electric contacts. The photocurrents generated in the modules are drawn independently of each other, which has the same problem as in the case of FIG.
[0016]
In the case of Conventional Example 3 described above, the first photovoltaic device has a thin-film two-terminal tandem structure in which the first and second photovoltaic cells are connected in series on one substrate. If the photocurrent generated in the cell and the photocurrent generated in the second photovoltaic cell are equal, and these photocurrents are not the optimal operating points of the two electromotive cells, high conversion efficiency cannot be obtained. For example, in Conventional Example 3, the first cell is amorphous and undergoes light deterioration, but the second cell is crystalline and does not undergo light deterioration. Since the first and second photovoltaic cells are connected in series, these currents must be equal in terms of the circuit, and the second cell is also affected by the photodegradation of the first cell. There is a problem that the current decreases. In addition, a back sheet was adhered to the back electrode side of the substrate with a sealing resin, but only a thin and non-strength back sheet was easily damaged in the installation work of the solar cell module, etc. there were.
[0017]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and provides an integrated thin-film photovoltaic device of a mechanical stack type so that the light of the first photovoltaic cell and the second photovoltaic cell can be reduced. Eliminating the conversion-efficiency by eliminating the current-limiting factor, narrowing the gap (close layer) between the two glass substrates, reducing the amount of transparent resin layer used for bonding, and reducing the cost. It is an object of the present invention to reduce transmission loss, prevent output reduction, and reduce the thickness to reduce the size of the device. Another object of the present invention is to make the transmitted light from the first integrated plurality of thin film photovoltaic unit cells irradiate the second integrated plurality of thin film photovoltaic unit cells equally. It is another object of the present invention to simplify lead connection of an output extraction unit. Still another object is to connect and enlarge a plurality of thin film photovoltaic devices in a plane. Further, it is another object of the present invention to protect the thin-film photovoltaic element by the second substrate, which eliminates the back sheet, can be reduced in cost, has excellent environmental resistance, and has excellent strength.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, an integrated thin-film photovoltaic device according to the present invention has a first integrated circuit in which a plurality of unit cells are connected in series on one main surface of a light-transmitting first substrate. A second integrated thin-film photovoltaic element comprising a plurality of unit cells connected in series on one principal surface of a second substrate having a conductive surface; A mechanical stack-type integrated thin-film photovoltaic device which faces each other such that the other main surfaces are located outside, wherein the first integrated circuit is formed when the main surfaces of both substrates are viewed in plan. The series connection direction of the unit cells of the type thin film photovoltaic element and the series connection direction of the unit cells of the second integrated type thin film photovoltaic element cross each other.
[0019]
In the integrated thin-film photovoltaic device, when the main surfaces of the two substrates are viewed in a plan view, the direction in which unit cells of the first integrated thin-film photovoltaic device are connected in series and the second integrated The direction in which the series connection of the unit cells of the thin-film photovoltaic element are perpendicular to each other, and the one main surface of the two substrates has an output extraction portion that does not overlap each other when the main surfaces of the two substrates are viewed in plan. It is characterized by having.
[0020]
Further, a close layer including a light-transmitting resin layer or a gas layer for heat insulation is interposed between the first integrated thin-film photovoltaic device and the second integrated thin-film photovoltaic device. Features.
[0021]
An integrated thin-film photovoltaic device is characterized in that an outer peripheral region on one main surface side of the two substrates is roughened.
[0022]
Further, the output take-out sections are electrically connected to each other.
[0023]
The thickness of the close contact layer is in the range of 0.01 mm to 20 mm.
[0024]
Also, a surface of the first integrated thin-film photovoltaic device, a surface of the second integrated thin-film photovoltaic device, one main surface of the first substrate, and one main surface of the second substrate Wherein at least one has a light confinement structure having an uneven shape.
[0025]
Further, at least a part thereof is transparent to form a see-through structure.
[0026]
Further, the outer peripheral portions of the first and second integrated thin-film photovoltaic elements are fixed by a protective frame.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. 1, 2, 3, 4, and 5 are schematic cross-sectional views of the integrated thin-film photovoltaic device of the present invention. In these figures, the arrow L indicates the incident direction of light.
[0028]
First, a first embodiment according to the present invention will be described in detail with reference to the drawings. FIGS. 1 and 2 are schematic cross-sectional views of the same integrated thin-film photovoltaic device (each photovoltaic device is formed by connecting a plurality of unit cells in series), but differing by 90 degrees (substrate main substrate). FIG. 3 is a schematic cross-sectional view in which the unit cells are arranged in series in a direction perpendicular to each other in plan view. That is, FIG. 2 is a sectional view taken along the line AA ′ shown in FIG.
[0029]
As shown in FIGS. 1 and 2, the integrated thin-film photovoltaic device of the present invention has a structure in which a plurality of unit cells are connected in series on one main surface of a first substrate 10 having translucency. One integrated thin-film photovoltaic element and a second integrated thin-film photovoltaic element in which a plurality of unit cells are connected in series on one main surface of a second substrate 60 having a conductive surface. A mechanical stack type integrated thin-film photovoltaic device in which the other main surfaces of both substrates 10 and 60 face each other so as to be located outside, wherein the main surfaces of both substrates 10 and 60 are viewed in plan. Sometimes, the series connection direction of the unit cells of the first integrated thin-film photovoltaic device and the series connection direction of the unit cells of the second integrated thin-film photovoltaic device intersect (optimally orthogonal). are doing. In particular, one main surface of both substrates 10 and 60 is characterized in that there is an output extraction portion that does not overlap each other when the main surfaces of both substrates 10 and 60 are viewed in plan.
[0030]
Specifically, the integrated thin-film photovoltaic device 1 includes a first integrated thin-film photoelectric element (unit cells 111, 112,...) Including a first substrate 10, and a second substrate. The second integrated thin film photoelectric element 16X (X = 1, 2,...) Provided with the first and second substrates 60 and 60 is disposed so as to face each other with the two substrates 10 and 60 outside. In the photovoltaic device 1, first integrated thin-film photoelectric elements (unit cells 111, 112,...) Are sequentially formed on a light-transmitting substrate 10 by a first light-transmitting conductive layer 21, 22,. . . . , First thin-film photovoltaic layers 31, 32,. . . . , And the second light-transmitting conductive layers 41, 42,. . . . Consisting of The second integrated thin-film photoelectric element 16X (X = 1, 2,...) Is formed on a conductive substrate having an insulating layer, which is the second substrate 60, or on the insulating substrate in order. It comprises a second thin-film photovoltaic layer 8X and a third translucent conductive layer 9X (X = 1, 2,...). The close layer between the two elements is formed of the light-transmitting resin layer 150 or the close layer 150 including the gas layer for heat insulation. Between the first integrated thin-film photoelectric elements (unit cells 111, 112,...), Separation grooves (series connection regions) 51, 52,. . . . , And between the second integrated thin-film photoelectric elements (unit cells 161, 162,...), Separation grooves (series connection regions) 101, 102,. . . . , There is.
[0031]
Further, output take-out portions 121 and 122 are provided on the first substrate end, and lead wires 131 and 132 are connected to the outside.
[0032]
The first thin-film photovoltaic layers 31, 32,. . . . , For example, comprises a stack of a first one-conductivity-type silicon-based semiconductor layer, a substantially intrinsic non-single-crystal silicon-based semiconductor layer, and a first reverse-conductivity-type silicon-based semiconductor layer (not shown). The second thin-film photovoltaic layer 8X (X = 1, 2,...) Is, for example, a second one-conductivity-type silicon-based semiconductor layer, a substantially intrinsic non-single-crystal silicon-based semiconductor. And a second reverse conductivity type silicon-based semiconductor layer (not shown). Compound semiconductors, dyes, and the like may be used for these thin film semiconductors in addition to silicon.
[0033]
FIG. 2 is a schematic cross-sectional view taken along the line AA ′ shown in FIG. The description of FIG. 2 is the same as that of FIG. 1 and will not be repeated.
[0034]
In the first embodiment of the present invention, as shown in FIGS. 1 and 2, the width of the first substrate and the width of the second substrate are the same.
[0035]
According to these, the series connection direction (integration direction) of the first integrated thin film photovoltaic elements (unit cells 111, 112,...) And the second integrated thin film photovoltaic element 161, 162,. . . . Are orthogonal to the series connection direction (integration direction) of the first integrated thin-film photoelectric element 111, the second integrated thin-film photoelectric element (unit cells 161, 162,...) 112,. . . . , And separation grooves 51, 52,. . . . , Can be evenly received by the transmitted light. Thereby, the second integrated thin-film photovoltaic elements 161, 162,. . . . The photocurrents in each element (unit cell) substantially match, and the photocurrents in each unit can be connected in series efficiently.
[0036]
1. The output extraction portions 121 and 122 and the lead wires 131 and 132 of the first integrated thin-film photovoltaic device 110 in FIG. 1 correspond to the output of the second integrated thin-film photovoltaic device 160 in FIG. The positions are shifted by 90 degrees from the extraction portions 171 and 172 and the lead wires 181 and 182, and even if the width of the first substrate 10 and the width of the second substrate 60 are equal, they do not overlap. Therefore, it is not necessary to consider and pay attention to the insulating property, the gap (close layer) between the two glass substrates can be narrowed, the amount of transparent resin used for bonding is reduced, the cost is reduced, and light transmission is reduced. The loss was reduced, and the output of the second series solar cell was not reduced, and the thickness of the bonded mechanical stack type solar cell module was reduced, so that the size could be reduced.
[0037]
Further, the first and / or second thin film photovoltaic layers of the present invention are provided with spontaneous irregularities due to the crystalline columnar deposition of the crystalline semiconductor layer, and the irregular structure with the close contact layer 150 made of this translucent resin layer. , The light confinement effect can be enhanced. Due to the improvement of the light confinement effect, the conversion efficiency is improved as compared with the related art.
[0038]
Further, according to the integrated thin-film photovoltaic device 1 of the present invention, the surface (one main surface) of the first substrate 10 or the first light-transmitting conductive layers 21, 22,. . . . , Are characterized in that their surfaces are uneven. As a result, an uneven surface is obtained at the incident position of the laminated structure, and selective incidence, refraction, and absorption of light become more active particularly in the first integrated thin-film photovoltaic device. This results in improved conversion efficiency.
[0039]
According to the integrated thin-film photovoltaic device of the present invention, the second substrate 60 or the conductive layers 71, 72,. . . . , Are characterized in that their surfaces are uneven. As a result, the first unevenness becomes more light-transmissive and the second unevenness becomes more light-reflective for long-wavelength light where light penetration is deeper than short-wavelength light, and the light confinement effect of long-wavelength light increases. This results in higher conversion efficiency.
[0040]
Further, by providing a close contact layer 150 made of a translucent resin having a large refractive index difference between the first and second thin-film photovoltaic layers between the first and second integrated thin-film photoelectric elements, the first integration is achieved. The light reflection to the thin-film photovoltaic device increases, and the conversion efficiency of the first integrated thin-film photovoltaic device can be improved. That is, when the close contact layer 150 is mainly a gas layer for heat insulation, the refractive index difference and the heat insulation are large and more effective. In addition, when the heat insulating gas layer is a reduced pressure gas layer or a vacuum layer, the refractive index difference and the heat insulating property are large and more effective. When the close contact layer 150 is a parallel layer of the gas layer for heat insulation and the light-transmitting resin layer, the gap between the two elements can be fixed by the light-transmitting resin layer and the thin film The mechanical stability of the device can be maintained. In particular, it is convenient to fix the outer periphery in the case of a non-integrated cell and fix the separation groove in the case of an integrated cell without adversely affecting efficiency. When the close contact layer 150 is a mixed layer of a gas and a light-transmitting resin material, the gap can be fixed on the entire surface and mechanical strength can be provided, and the repetition of the gas and the light-transmitting resin material is performed on the order of the wavelength of light. By doing so, the light reflectance can be increased.
[0041]
Further, in FIG. 1, in the output extraction portion 121 of the first substrate 10 and the region 141 which is an opposing portion of the second substrate facing the output extraction portion 121, the light transmitting substrate 10 and the second substrate A region (not shown) where the first light-transmitting conductive layer 21 and the second conductive layer 7X are not provided on the outer periphery of one main surface of the first and second substrates is provided on the substrate 60. By roughening the surface of the base substrate (protruding area), a stronger adhesion can be secured when the output take-out part and the lead wire attachment part are sealed with resin, and it has excellent environmental resistance and moisture resistance. It becomes sealing. The same applies to the other substrate end. In this manner, at least the thin film is removed at the outer peripheral portion on one main surface of the first substrate 10 and the outer peripheral portion on the one main surface of the second substrate 60, and furthermore, the substrate is made uneven, so that there is no peeling of the film and the adhesion area is also small Increased encapsulation provides excellent environmental resistance and moisture resistance.
[0042]
Further, the thickness of the close contact layer in the integrated thin film photovoltaic device 1 of the present invention is characterized in that it is in the range of 0.01 mm to 20 mm. This is because if the thickness of the close contact layer is 0.01 μm or less, there is a possibility that a problem may occur in the insulating property between the first integrated thin-film photoelectric element and the second integrated thin-film photoelectric element. This is because the thickness of the integrated thin-film photovoltaic device 1 becomes large, and it becomes impossible to reduce the size of the module.
[0043]
In FIG. 1, the output extraction portions 121 and 122 and the lead wires 131 and 132 of the first integrated thin film photovoltaic device 110 are the output extraction portions of the second integrated thin film photovoltaic device 160 of FIG. Since the output can be taken out independently of the 171 and 172 and the lead wires 181 and 182, each can be operated at the optimum operating point, so that high conversion efficiency can be obtained.
[0044]
In addition, by providing a second substrate that is thicker, stronger, and more environmentally resistant than the conventional back sheet, etc. on the back electrode side, there is a danger of scratching during installation work of the solar cell module and caution in handling. Is almost eliminated, and a highly reliable solar cell module can be provided.
[0045]
Next, a second embodiment according to the present invention will be described in detail with reference to the drawings. FIGS. 3 and 4 are schematic cross-sectional views of the same integrated thin-film photovoltaic device, but different from each other by 90 degrees. That is, FIG. 4 is a sectional view taken along the line AA ′ shown in FIG.
[0046]
The difference between the first embodiment and the second embodiment is that the width of the first substrate 10 and the width of the second substrate 60 are different as shown in FIGS. That is, the width on the substrate side having the portions and the lead wires is increased.
[0047]
Thereby, connection of a lead wire or the like from the output take-out unit is facilitated. That is, after the first substrate and the second substrate are bonded via the close-contact layer, the connection operation of the lead wire or the like from the output extraction portion can be easily performed without hindrance.
[0048]
Next, a third embodiment according to the present invention will be described in detail with reference to the drawings. FIG. 5 is a schematic cross-sectional view showing an embodiment in which a plurality of integrated thin-film photovoltaic devices according to the second embodiment are connected. Although this cross-sectional schematic diagram illustrates a case where three integrated thin-film photovoltaic devices are connected in a plane in a horizontal direction, more generally, a plurality of integrated thin-film photovoltaic devices are connected in a plane. Connected. A plurality of integrated thin-film photovoltaic devices are also connected in a plane in the vertical direction.
[0049]
The integrated thin-film photovoltaic device 1 of the present embodiment includes a first integrated thin-film photovoltaic device 21, a second integrated thin-film photovoltaic device 22,. . . . , Consisting of Here, the first integrated thin-film photovoltaic device 21 is in close contact with the first substrate 11, the first integrated thin-film photoelectric device 111, the second substrate 61, and the second integrated thin-film photoelectric device 161. It is composed of layers. The second integrated thin-film photovoltaic devices 22,. . . . And so on. As shown in FIG. 5, except for the final output take-out portions 121 and 122 and the lead wires 131 and 132 at both ends, the output take-out portions are alternately connected almost directly by an elastic or welded conductor or the like. By laterally bonding the end surface of the first substrate 11 and the end surface of the first substrate 12 and the end surface of the second substrate 61 and the end surface of the second substrate 62 directly or by bonding via a buffer spacer. In addition, the integrated thin-film photovoltaic device can be expanded in the lateral direction. Similarly, the integrated thin-film photovoltaic device can be expanded in the vertical direction. Thus, the integrated thin-film photovoltaic device 1 mechanically enlarged in a plane can be manufactured.
[0050]
In this way, a large number of integrated thin-film photovoltaic devices are manufactured with a small substrate size using a small-sized plasma CVD device which is excellent in uniformity and is easily available. An integrated thin-film photovoltaic device 1 having a size can be manufactured.
[0051]
Further, according to the integrated thin-film photovoltaic device of the present invention, the amorphous silicon-based semiconductor layer 22 and the crystalline silicon-based semiconductor layer 72 are each independently formed without being continuously deposited by the chemical vapor deposition method. It is characterized by being deposited under conditions.
[0052]
The second substrate 60 is a light-transmitting substrate, and the conductive layers 71, 72,. . . . Are uniformly rejected to obtain a see-through integrated thin-film photovoltaic device 1 that transmits external light.
[0053]
Further, the mechanical strength of the integrated thin-film photovoltaic device 1 of the present invention can be increased by fixing at least the outer periphery of the end portion of the integrated thin-film photovoltaic device 1 with the protective frame.
[0054]
【Example】
Hereinafter, the present invention will be described with reference to Examples 1 to 4, which show the present invention more specifically.
<Example 1>
1 and 2, reference numeral 1 denotes an integrated thin-film photovoltaic device. Reference numeral 10 denotes a light-transmitting substrate. In this embodiment, as the light-transmitting substrate, blue plate glass (1.8 mm in thickness) having both flat surfaces is used. As other translucent substrates, various glasses such as white plate glass, transparent inorganic substrates such as sapphire, transparent organic resin substrates such as polycarbonate, and the like may be used. 21, 22,. . . . Is a first light-transmitting conductive film. In this embodiment, an ITO film deposited by a sputtering method is used, but an SnO2 film by a thermal CVD method, a spray method, or the like may be used. Hereinafter, the separation grooves 51, 52,. . . . Are formed by laser irradiation as needed, but may be formed by a photo process. As another light-transmitting conductive film, a SnO 2 film, a ZnO (impurity-doped) film deposited by a sputtering method or the like may be used, or these light-transmitting conductive films may be stacked and used. 31, 32,. . . . Is an amorphous silicon-based semiconductor film having a PIN junction. A hydrogenated amorphous silicon-based film is used as a PIN junction semiconductor formed by stacking a P-type semiconductor film, an I-type semiconductor film, and an N-type semiconductor film. In the example, deposition is performed by a plasma CVD method, but deposition may be performed by a catalytic CVD method or the like. In the present embodiment, a PIN junction in which a P-type semiconductor film is provided on the side of the first light-transmitting conductive film is used, but an NIP junction of a reverse junction may be used. If the I-type semiconductor film is amorphous, the P-type semiconductor film and / or the N-type semiconductor film may be microcrystalline. Also, a hydrogenated amorphous silicon alloy-based film may be used. For example, for the P film on the light incident side, hydrogenated amorphous silicon carbide is more preferable because it enhances the light transmission and reduces light penetration loss.
[0055]
41, 42,. . . . Is a second light-transmitting conductive film, and an ITO film was deposited by a sputtering method. As the other second light-transmitting conductive film, ZnO, SnO2: F, or the like may be used, or a stacked film of these may be used. Further, a collector electrode having an Ag film deposited thereon to form an electrode pattern such as a comb shape may be provided.
[0056]
Reference numeral 60 denotes a conductive substrate or an insulating substrate provided with an insulating layer, on which conductive layers 71, 72,. . . . , The second thin-film photovoltaic layers 81, 82,. . . . , And the third light-transmitting conductive layers 91, 92,. . . . In this example, 1.8 mmt of soda lime glass, which is an insulating substrate, was used. As another substrate, an inorganic substrate such as various kinds of glass, an organic resin substrate such as polycarbonate, or a conductive substrate such as an aluminum substrate or a stainless steel substrate may be used.
[0057]
71, 72,. . . . Denotes a light-reflective conductive film. In this embodiment, a laminated film of Ti / Ag / Ti is used. The Ti film on the substrate side is for promoting adhesion, and the Ti film on the Ag film is for suppressing Ag diffusion into the semiconductor film. The Ag film has high light reflectivity, and high conversion efficiency is easily obtained. As another material configuration, Ti / Ag: Al alloy / ZnO: Al may be used.
[0058]
81, 82,. . . . Is a crystalline silicon-based semiconductor film having a PIN junction, and is a microcrystalline silicon-based film having a relatively high crystallization rate obtained by deposition by a plasma CVD method, a catalytic CVD method, or the like. And a PIN junction semiconductor formed by laminating an I-type semiconductor film and an N-type semiconductor film. If the I-type semiconductor film is microcrystalline, the P-type semiconductor film and / or the N-type semiconductor film may be amorphous. In this example, NIP type semiconductor films were continuously deposited on the glass substrate with the light-reflective conductive film by a plasma CVD method. Although the NIP junction in which the N-type semiconductor film is provided on the light reflective conductive film side is used, a PIN junction of a reverse junction may be used. Alternatively, a microcrystalline silicon alloy-based film may be used. In this embodiment, a plasma CVD method is used. 91, 92,. . . . Denotes a third light-transmitting conductive film. In this embodiment, an ITO film is deposited by a sputtering method. As the other second light-transmitting conductive film, ZnO: Al, SnO2: F, or the like may be used, or a stacked film of these may be used. Further, a collector electrode similar to the above may be formed thereon.
[0059]
Reference numeral 150 denotes a translucent resin. In this embodiment, a transparent sealing resin EVA (ethylene-vinyl acetate copolymer resin) was used. An EVA sheet is sandwiched between both substrates, and these are reduced in pressure. The integrated thin-film photoelectric element 1 is formed by a process including melting of a resin by heating, compression / filling of EVA, thermosetting, primary cooling, release to atmospheric pressure, and secondary cooling. Was prepared.
Further, as the outer frame of the integrated thin-film photoelectric element 1, a protective frame made of an aluminum material having a U-shaped cross section was used. In addition to aluminum, a metal material such as stainless steel or a hard plastic such as FTP may be used.
[0060]
<Example 2>
3 and 4, reference numeral 1 denotes an integrated thin-film photovoltaic device. Numeral 11 denotes a light-transmitting substrate, numeral 60 denotes a conductive substrate or an insulating substrate provided with an insulating layer, and the size of these substrates is approximately 10 mm as shown in FIG. 3 and FIG. ). Subsequent steps were the same as in Example 1.
[0061]
【The invention's effect】
According to the integrated thin-film photovoltaic device of the present invention, the direction in which the first integrated thin-film photovoltaic device is connected in series (integration direction) and the direction in which the second integrated thin-film photovoltaic device is connected in series When the (integration directions) cross (optimally orthogonal), the second integrated thin-film photoelectric element uniformly receives the influence of the transmitted light from the first integrated thin-film photoelectric element and the separation groove. be able to. As a result, the photocurrents in the respective elements (units) of the second integrated thin-film photovoltaic element substantially match, and the photocurrents of the respective units can be connected in series efficiently, so that the conversion efficiency is improved.
[0062]
According to the first and second aspects, the output of the first integrated thin-film photovoltaic device and the output of the second integrated thin-film photovoltaic device can be output independently. , Each of which operates at an optimum operating point to obtain high conversion efficiency.
The output extraction of the first integrated thin-film photovoltaic element and the output extraction of the second integrated thin-film photovoltaic element can be directly connected to extract the output at the same voltage. High conversion efficiency is obtained by operating at the point. Furthermore, a second substrate that is thicker, stronger and more environmentally resistant than a conventional back sheet or the like can be provided on the back electrode side. Attention is lost, and a highly reliable solar cell module can be provided. Further, for example, the width of the first substrate is different from the width of the second substrate, and the output take-out part and the lead wire are provided at the end of the substrate, so that connection of the lead wire from the output take-out part can be easily performed. That is, after the first substrate and the second substrate are bonded via the close contact layer, a connection operation of a lead wire or the like from the output extraction portion can be performed without any obstacle. Furthermore, so that a plurality of integrated thin-film photovoltaic devices are alternately positioned in a plane in a horizontal direction, the output take-out portions are directly connected alternately by an elastic conductor or the like without using a lead wire, By directly bonding the end face of the substrate and the end face of the substrate facing the end face via a spacer or a spacer, an integrated thin-film photovoltaic device mechanically enlarged in a planar shape can be manufactured. As a result, a plurality of integrated thin-film photovoltaic devices are manufactured on a small-sized substrate using a small-sized plasma CVD device that is highly uniform and easily available, and these are mechanically enlarged in a planar manner. A large-sized integrated thin-film photovoltaic device can be manufactured.
[0063]
According to the second aspect of the present invention, the output take-out part and the lead wire of the first integrated thin-film photovoltaic element are shifted by 90 degrees from the output take-out part and the lead wire of the second integrated thin-film photovoltaic element. Even if the width of the first substrate is equal to the width of the second substrate, they do not overlap. Therefore, insulation is ensured, the gap (close layer) between the two glass substrates can be narrowed, the amount of transparent resin used for bonding is reduced, cost is reduced, and light transmission loss is reduced, and the second The output of the series-type solar cell does not decrease, and the thickness of the bonded mechanical stack type solar cell module is reduced, so that the size can be reduced.
[0064]
According to the third aspect, a close contact layer made of a light-transmitting resin having a large difference in refractive index from the first and second thin-film photovoltaic layers is provided between the first and second integrated thin-film photoelectric elements. Accordingly, light reflection to the first integrated thin-film photovoltaic element increases, and the conversion efficiency of the first integrated thin-film photovoltaic element can be improved. That is, when such a close layer is mainly a heat insulating gas layer, the refractive index difference and the heat insulating property are large and more effective. In addition, when the heat insulating gas layer is a reduced pressure gas layer or a vacuum layer, the refractive index difference and the heat insulating property are large and more effective. When the close contact layer is a parallel layer of the gas layer for heat insulation and the light-transmitting resin layer, the gap between the two elements can be fixed by the light-transmitting resin layer together with the effect of the gas layer for heat insulation, and the thin-film photovoltaic device Mechanical stability can be maintained. In particular, it is convenient to fix the outer periphery in the case of a non-integrated cell and fix the separation groove in the case of an integrated cell without adversely affecting efficiency. When the close layer is a mixed layer of a gas and a translucent resin material, the gap can be fixed on the entire surface and mechanical strength can be provided, and the repetition of the gas and the translucent resin material is on the order of the wavelength of light. This can increase the light reflectance.
[0065]
According to the fourth aspect, for example, in a region which is an output take-out portion of the first substrate and an opposing portion of the second substrate opposed thereto, the first light-transmitting conductive layer serving as a base for these portions And the second conductive layer are removed, and furthermore, the surface of the outer peripheral portion of the light-transmitting substrate and the second substrate, which are the bases thereof, are roughened, so that the output take-out portion and the lead wires are sealed with resin. As a result, stronger adhesion can be ensured, and sealing excellent in environmental resistance and moisture resistance can be performed. The same applies to the other substrate end. In this manner, the thin film is removed from the outer peripheral portion of the first substrate and the outer peripheral portion of the second substrate, and furthermore, the surface is roughened, whereby sealing with excellent environmental resistance and moisture resistance can be performed.
[0066]
According to the sixth aspect, the thickness of the close contact layer is in the range of 0.01 mm to 20 mm, and the thickness of the close contact layer is 0.01 μm or more. When the thickness of the integrated thin film photovoltaic device is reduced to 20 mm or less, the thickness of the integrated thin film photovoltaic device of the present invention can be reduced, and the module can be downsized.
[0067]
According to the seventh aspect, the surface of the first light-transmitting substrate or the surface of the first light-transmitting conductive layer has irregularities, so that an irregular surface is obtained at the incident position of the laminated structure. In particular, selective incidence, refraction and absorption of light become more active in the first integrated thin-film photovoltaic device, and the conversion efficiency can be improved by increasing the effect of confining short-wavelength light. In addition, since the surface of the second insulating substrate or the surface of the conductive layer has irregularities, it becomes more light-reflective to long-wavelength light, which has a deeper penetration of light than short-wavelength light, and the light confinement effect of long-wavelength light is reduced. An even higher conversion efficiency can be obtained.
[0068]
According to the eighth aspect, for example, a see-through type in which external light is transmitted by, for example, using an insulating substrate as a light-transmitting substrate and uniformly removing a part of the conductive layer in the second integrated thin-film photovoltaic element. Can be obtained.
[0069]
According to the ninth aspect, the mechanical strength of the integrated thin-film photovoltaic device of the present invention can be increased by fixing at least the outer periphery of the end portion of the integrated thin-film photovoltaic device with the protective frame. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating one embodiment of an integrated thin-film photovoltaic device according to the present invention.
FIG. 2 is a cross-sectional view schematically illustrating one embodiment of an integrated thin-film photovoltaic device according to the present invention.
FIG. 3 is a cross-sectional view schematically illustrating another embodiment of the integrated thin-film photovoltaic device according to the present invention.
FIG. 4 is a cross-sectional view schematically illustrating another embodiment of the integrated thin-film photovoltaic device according to the present invention.
FIG. 5 is a cross-sectional view schematically illustrating an integrated thin-film photovoltaic device according to the present invention.
FIG. 6 is a cross-sectional view illustrating an example of a conventional integrated thin-film photovoltaic device.
FIG. 7 is a cross-sectional view illustrating an example of a conventional integrated thin-film photovoltaic device.
[Explanation of symbols]
1: Integrated thin-film photovoltaic device
10, 11, 12: translucent substrate (first substrate)
21, 22,. . . . : First translucent conductive layer
31, 32,. . . . : First thin-film photovoltaic layer
41, 42,. . . . : Second translucent conductive layer
51, 52,. . . . : Separation groove (series connection area)
60, 61, 62: a conductive substrate provided with an insulating layer or an insulating substrate (second substrate)
71, 72,. . . . : Conductive layer
81, 82,. . . . : Second thin-film photovoltaic layer
91, 92,. . . . : Third translucent conductive layer
110: First integrated thin-film photovoltaic device
121, 122,. . . . ： Output extraction unit
131, 132,. . . . :Lead
150: Close layer
160: Second integrated thin-film photovoltaic device

Claims

A first integrated thin-film photovoltaic element in which a plurality of unit cells are connected in series on one main surface of a light-transmitting first substrate, and a second substrate having a conductive surface. A mechanical stack type in which a second integrated thin-film photovoltaic element having a plurality of unit cells connected in series on a main surface thereof and facing each other such that the other main surfaces of the two substrates are located outside; The integrated thin-film photovoltaic device according to the above, wherein when the main surfaces of the two substrates are viewed in a plan view, the series connection direction of the unit cells of the first integrated thin-film photovoltaic element and the second integrated An integrated thin-film photovoltaic device, wherein the series connection direction of the unit cells of the thin-film photovoltaic element crosses each other.

2. The integrated thin-film photovoltaic device according to claim 1, wherein when the main surfaces of the two substrates are viewed in a plan view, a direction in which unit cells of the first integrated thin-film photovoltaic element are connected in series, and The integrated type, wherein the direction of series connection of the unit cells of the second integrated type thin-film photovoltaic element is orthogonal to each other, and an output extraction portion which does not overlap each other is provided on one main surface of both substrates. Thin film photovoltaic device.

3. The integrated thin-film photovoltaic device according to claim 1, wherein a light transmitting property is provided between the first integrated thin-film photovoltaic device and the second integrated thin-film photovoltaic device. 4. An integrated thin-film photovoltaic device characterized by interposing a close layer including a resin layer or a gas layer for heat insulation.

4. The integrated thin-film photovoltaic device according to claim 1, wherein an outer peripheral region on one principal surface side of both substrates is roughened.

3. The integrated thin-film photovoltaic device according to claim 2, wherein said output extraction portions are electrically connected to each other.

The integrated thin-film photovoltaic device according to claim 3, wherein the thickness of the close contact layer is in a range of 0.01 mm to 20 mm.

The integrated thin-film photovoltaic device according to any one of claims 1 to 6, wherein a surface of the first integrated thin-film photovoltaic device, a surface of the second integrated thin-film photovoltaic device, An integrated thin-film photovoltaic device, wherein at least one of a main surface of the first substrate and a main surface of the second substrate has a light confinement structure having an uneven shape.

8. The integrated thin-film photovoltaic device according to claim 1, wherein at least a part of the integrated thin-film photovoltaic device has a see-through structure.

The integrated thin-film photovoltaic device according to any one of claims 1 to 8, wherein outer peripheral portions of the first and second integrated thin-film photovoltaic elements are fixed by a protective frame. Integrated thin-film photovoltaic device.