JP2001085714A - Solar battery cell for light convergence power generation - Google Patents

Solar battery cell for light convergence power generation

Info

Publication number
JP2001085714A
JP2001085714A JP25559799A JP25559799A JP2001085714A JP 2001085714 A JP2001085714 A JP 2001085714A JP 25559799 A JP25559799 A JP 25559799A JP 25559799 A JP25559799 A JP 25559799A JP 2001085714 A JP2001085714 A JP 2001085714A
Authority
JP
Japan
Prior art keywords
receiving surface
power generation
solar cell
region
light receiving
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP25559799A
Other languages
Japanese (ja)
Inventor
Kenji Araki
建次 荒木
Masashi Yamaguchi
真史 山口
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daido Steel Co Ltd
Original Assignee
Daido Steel Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daido Steel Co Ltd filed Critical Daido Steel Co Ltd
Priority to JP25559799A priority Critical patent/JP2001085714A/en
Publication of JP2001085714A publication Critical patent/JP2001085714A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • Y02E10/52—PV systems with concentrators
    • 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
    • Y02E10/547—Monocrystalline silicon PV cells

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery cell for light convergence power generation, where deterioration of power generating efficiency which is generated by irregularities in irradiation on a light-receiving surface is reduced, when a load is connected. SOLUTION: In a solar battery cell 16, a recombination reducing means is installed, where the pitch of a thin-line part of a comb-shaped upper electrode 22 arranged on a central region A of alight receiving surface 14 is made greater than almost three times that in the other region, and the density of an arranged number is reduced to almost one third. Since a recombination current in the central region A is reduced, consumption of current generated in the other region becomes low, and the power generating efficiency with a load connected can be improved.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、集光発電用太陽電
池セルに関し、特に、その発電効率を高める技術に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic cell for concentrating power generation, and more particularly to a technique for improving the power generation efficiency.

【０００２】[0002]

【従来の技術】受光面側にエミッタ層が設けられた集光
発電用太陽電池セルと、その太陽電池セルの受光面に太
陽光を集光する集光器とを備えた集光式太陽光発電装置
が知られている。これによれば、太陽光が集光器により
集光されてから太陽電池セルに照射されるために太陽電
池セルが小型となって装置が安価となるとともに、太陽
電池セルの変換効率がたとえば１７％程度まで高められ
る利点がある。2. Description of the Related Art A concentrating solar cell including a solar cell for concentrating power generation having an emitter layer provided on a light receiving surface side and a concentrator for condensing sunlight on the light receiving surface of the solar cell. Power generation devices are known. According to this, since the solar cell is irradiated with the solar light after being condensed by the light collector, the size of the solar cell is reduced and the device is inexpensive, and the conversion efficiency of the solar cell is, for example, 17%. %.

【０００３】[0003]

【発明が解決しようとする課題】ところで、上記集光発
電用太陽電池セルの受光面には、集光器により太陽光が
集光させられるが、一様な照射とはならず、たとえば受
光面の中心部が周辺部よりも集光照度が高くなる場合が
多い。このような場合には、一様照射に比較して、中心
部における再結合電流（すなわち光子の入射により発生
させられた１対の電子および正孔が再び結合することに
よる電流減少分）が増大して周辺部からのキャリヤを食
ってしまうため、一様照射よりも発電効率が低下し、集
光比に応じて負荷接続時の発電電力が得られないという
欠点があった。図１０および図１１はその一例である。
図１０は、集光照度すなわち不均一照射における出力電
流および電力を、一様照射の場合と比較して示してお
り、図１１は、集光照度分布の半値幅の比（半値幅／集
光発電用太陽電池セルの受光面の開口幅）に対する発電
効率を集光倍率１０乃至５０の範囲で示している。図１
０から明らかなように、不均一照射における出力電流お
よび電力は一様照射の場合よりも最大電力付近すなわち
負荷接続時付近で下回っており、図１１から明らかなよ
うに、集光照度分布の半値幅の比が大きくなるほど、ま
た集光倍率が高くなるほど、発電効率の伸びが抑制され
ている。By the way, sunlight is condensed on the light receiving surface of the solar cell for concentrating power generation by the light concentrator, but the light is not uniformly irradiated. In many cases, the concentrated illuminance is higher at the central part than at the peripheral part. In such a case, the recombination current at the center (that is, the current decrease due to the recombination of a pair of electrons and holes generated by the incidence of photons) is increased as compared with the uniform irradiation. As a result, the carrier from the periphery is consumed, so that the power generation efficiency is lower than in the case of uniform irradiation, and there is a drawback that the power generated when the load is connected cannot be obtained according to the light collection ratio. FIG. 10 and FIG. 11 are examples.
FIG. 10 shows the condensed illuminance, that is, the output current and the electric power in the non-uniform irradiation in comparison with the case of the uniform irradiation. FIG. 11 shows the ratio of the half width of the condensed illuminance distribution (half width / condensing power generation). The power generation efficiency with respect to the aperture width of the light receiving surface of the solar cell is shown in the range of the condensing magnification of 10 to 50. FIG.
0, the output current and the power in the non-uniform irradiation are lower near the maximum power, that is, in the vicinity of when the load is connected, than in the case of the uniform irradiation. As is clear from FIG. As the ratio of the light-emitting element becomes larger and the light-gathering magnification becomes higher, the increase in the power generation efficiency is suppressed.

【０００４】本発明は、以上の事情を背景として為され
たものであり、その目的とするところは、受光面におけ
る照射むらに起因する負荷接続時の発電効率の低下を少
なくした集光発電用太陽電池セルを提供することにあ
る。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the power generation efficiency when a load is connected due to uneven irradiation on the light receiving surface. It is to provide a solar cell.

【０００５】本発明者は、上記目的を達成するために種
々検討を重ねた結果、集光発電用太陽電池セルの受光面
における太陽光の照射が不均一となると、高い集光照度
の領域ほど、光入射により生成させられた再結合電流が
多くなって、その周辺部で発生した電流を食ってしまう
ことが原因であるという仮説を基にして、高い集光照度
の領域ほど電子および正孔の再結合が発生し難くする構
成、たとえば高い集光照度の領域ほど櫛型電極間隔を大
きくすると、一様照射の場合の出力効率に近い効率が得
られることを見いだした。本発明はこのような知見に基
づいて為されたものである。The inventor of the present invention has conducted various studies to achieve the above object. As a result, when the irradiation of sunlight on the light receiving surface of the solar cell for concentrating power generation becomes non-uniform, the region of higher condensing illuminance becomes Based on the hypothesis that the recombination current generated by light incidence increases and consumes the current generated in the surrounding area, the recombination of electrons and holes in the region of higher condensed illuminance is It has been found that an efficiency close to the output efficiency in the case of uniform irradiation can be obtained by making the configuration in which the coupling hardly occurs, for example, by increasing the interval between the comb-shaped electrodes in the region of high condensing illuminance. The present invention has been made based on such findings.

【０００６】[0006]

【課題を解決するための手段】すなわち、本発明の要旨
とするところは、太陽光を受けるための受光面を備え、
その受光面の所定の領域ほど高い集光照度で照射される
集光発電用太陽電池セルにおいて、前記受光面の所定の
領域に、他の領域に比較して電子および正孔の再結合を
減少させる再結合減少手段を設けたことにある。That is, the gist of the present invention is to provide a light receiving surface for receiving sunlight,
In a photovoltaic cell for concentrating power generation, which is irradiated with a higher converging illuminance in a predetermined area of the light receiving surface, recombination of electrons and holes is reduced in a predetermined area of the light receiving surface as compared with other areas. That is, a means for reducing recombination is provided.

【０００７】[0007]

【発明の効果】このようにすれば、集光発電用太陽電池
セルの受光面のうち相対的に高い集光照度で照射される
所定の領域には、相対的に低い集光照度で照射される他
の領域に比較して電子および正孔の再結合を減少させる
再結合減少手段が設けられていることから、上記所定の
領域における再結合電流が少なくなって上記他の領域で
発生した電流を食うことが少なくなるので、負荷接続時
の発電効率が高められる。According to this configuration, a predetermined area of the light receiving surface of the solar cell for concentrating power generation, which is irradiated with relatively high concentrated illuminance, is irradiated with relatively low concentrated illuminance. Since the recombination reducing means for reducing the recombination of electrons and holes is provided as compared with the region, the recombination current in the predetermined region is reduced and the current generated in the other region is consumed. Power generation efficiency at the time of load connection is increased.

【０００８】[0008]

【発明の他の態様】ここで、好適には、前記集光発電用
太陽電池セルは、所定の間隔を隔てて互いに平行な複数
本の導体を含む櫛型電極を受光面に備えたものであり、
前記再結合減少手段は、その受光面の前記所定の領域に
配置される櫛型電極の被覆率またはその櫛型電極の幅を
前記他の領域に比較して小さくし、或いはその櫛型電極
のピッチをその他の領域に比較して大きくしたものであ
る。このようにすれば、相対的に高い集光照度で照射さ
れる所定の領域に配置される櫛型電極の被覆率またはそ
の櫛型電極の幅が相対的に低い集光照度で照射される他
の領域に比較して小さくされるか、或いは相対的に高い
集光照度で照射される所定の領域に配置される櫛型電極
のピッチが相対的に低い集光照度で照射される他の領域
に比較して大きくされるので、上記所定の領域における
再結合電流が少なくなって上記他の領域で発生した電流
を食うことが少なくなり、負荷接続時の発電効率が高め
られる。In another preferred embodiment of the present invention, the solar cell for concentrating power generation preferably has a comb-shaped electrode including a plurality of conductors parallel to each other at a predetermined interval on a light receiving surface. Yes,
The recombination reducing unit reduces the coverage of the comb-shaped electrode or the width of the comb-shaped electrode arranged in the predetermined region of the light-receiving surface as compared with the other region, or The pitch is larger than other areas. In this way, the coverage of the comb-shaped electrode or the other area where the width of the comb-shaped electrode is irradiated with the relatively low condensed illuminance is arranged in the predetermined region irradiated with the relatively high condensed illuminance. The pitch of the comb-shaped electrodes arranged in a predetermined area irradiated with relatively high condensed illuminance is smaller than that of the other areas irradiated with relatively low condensed illuminance. Since it is increased, the recombination current in the predetermined region is reduced, and the current generated in the other region is less consumed, and the power generation efficiency when the load is connected is increased.

【０００９】また、好適には、前記集光発電用太陽電池
セルは、不純物が拡散されることによりｎ型或いはｐ型
半導体とされたエミッタ層を前記受光面側に備えたもの
であり、前記再結合減少手段は、その受光面の前記所定
の領域における不純物濃度が前記他の領域に比較して低
くされたものである。このようにすれば、相対的に高い
集光照度で照射される所定の領域における不純物濃度が
相対的に低い集光照度で照射される他の領域に比較して
低くされていることから、上記所定の領域における再結
合電流が少なくなって上記他の領域で発生した電流を食
うことが少なくなるので、負荷接続時の発電効率が高め
られる。Preferably, the solar cell for concentrating power generation has an emitter layer formed of an n-type or p-type semiconductor by diffusing impurities on the light-receiving surface side. In the recombination reducing means, the impurity concentration in the predetermined region of the light receiving surface is lower than that in the other region. With this configuration, the impurity concentration in the predetermined region irradiated with the relatively high condensed illuminance is lower than that in the other region irradiated with the relatively low condensed illuminance. Since the recombination current in the region is reduced and the current generated in the other region is less consumed, the power generation efficiency when the load is connected is improved.

【００１０】また、好適には、前記集光発電用太陽電池
セルは、その受光面から所定の深さ位置にＰＮ接合を備
えたものであり、前記再結合減少手段は、その受光面の
前記所定の領域における受光面からのＰＮ接合の深さ位
置が前記他の領域に比較して大きくされたものである。
このようにすれば、相対的に高い集光照度で照射される
所定の領域における受光面からのＰＮ接合の深さ位置が
相対的に低い集光照度で照射される他の領域に比較して
大きく（深く）されていることから、上記所定の領域に
おける再結合電流が少なくなって上記他の領域で発生し
た電流を食うことが少なくなるので、負荷接続時の発電
効率が高められる。Preferably, the solar cell for concentrating power generation has a PN junction at a predetermined depth position from a light receiving surface thereof, and the recombination reducing means includes a PN junction at the light receiving surface. The depth position of the PN junction from the light receiving surface in a predetermined area is made larger than that in the other areas.
By doing so, the depth position of the PN junction from the light receiving surface in the predetermined region irradiated with the relatively high condensed illuminance is larger than the other region irradiated with the relatively low condensed illuminance ( (Deep), the recombination current in the predetermined area is reduced, and the current generated in the other area is less consumed, so that the power generation efficiency when the load is connected is increased.

【００１１】[0011]

【発明の好適な実施の形態】以下、本発明の一実施例の
集光発電用太陽電池セル１６を図面を参照して詳細に説
明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solar cell 16 for concentrating power generation according to an embodiment of the present invention will be described in detail with reference to the drawings.

【００１２】図１において、集光式太陽光発電装置１０
は、太陽光Ｌを数十分の１程度の面積に集光する集光ミ
ラー１２と、この集光ミラー１２により集光された太陽
光Ｌを受ける受光面１４を備えた太陽電池セル１６とを
備えている。この集光ミラー１２は、太陽光Ｌを集光し
て太陽電池セル１６の受光面１４の中央部を中心として
照射する集光器として機能している。上記太陽電池セル
１６の受光面１４は、上記集光ミラー１２の焦点付近或
いは結像点付近において、その焦点或いは結像よりも大
きくなるように配置されるので、均一の照度で照射され
ない。たとえば図２に示すような分布に従って照射され
る。In FIG. 1, a concentrating solar power generation device 10
A solar cell 16 having a light-receiving surface 14 for receiving the sunlight L condensed by the light-collecting mirror 12; It has. The condenser mirror 12 functions as a condenser that collects the sunlight L and irradiates the sunlight L around the center of the light receiving surface 14 of the solar cell 16. The light receiving surface 14 of the solar cell 16 is arranged near the focal point or the image forming point of the condenser mirror 12 so as to be larger than the focal point or the image forming point. For example, irradiation is performed according to a distribution as shown in FIG.

【００１３】上記太陽電池セル１６は、図３に示すよう
に、０．５ｍｍ程度の厚みを有する半導体たとえば単結
晶或いは多結晶のシリコン板２０と、その単結晶シリコ
ン板２０の底面に固着された底部電極２１と、その単結
晶シリコン板２０の上面すなわち受光面１４に所定間隔
で平行に設けられた櫛型の上部電極２２とを備えてい
る。上記単結晶シリコン板２０内には、たとえば不純物
としてホウ素（Ｂ）が５×１０18ｃｍ-3程度の高濃度で
拡散されることによりｐ型とされたコンタクト層２４
と、たとえば不純物としてホウ素（Ｂ）が１×１０16ｃ
ｍ-3程度の濃度で拡散されることによりｐ型とされたＰ
層２６と、たとえば不純物として燐（Ｐ）が拡散される
ことによりｎ型とされたＮ層２８とが下側から上側へ順
次設けられている。このＮ層２８は、その上面は前記受
光面１４であり、光が入射させられるエミッタ層として
機能している。このＮ層２８は、たとえば５×１０19乃
至１×１０17cm-3の不純物濃度と、０．６乃至１０μｍ
の厚みを備えている。As shown in FIG. 3, the solar cell 16 is a semiconductor having a thickness of about 0.5 mm, for example, a single-crystal or polycrystalline silicon plate 20, and is fixed to the bottom surface of the single-crystal silicon plate 20. A bottom electrode 21 and a comb-shaped upper electrode 22 provided in parallel at a predetermined interval on the upper surface of the single crystal silicon plate 20, that is, the light receiving surface 14 are provided. In the single-crystal silicon plate 20, for example, boron (B) as an impurity is diffused at a high concentration of about 5 × 10 18 cm −3 to form a p-type contact layer 24.
And boron (B) as an impurity is 1 × 10 16 c
P which is made p-type by being diffused at a concentration of about m -3
A layer 26 and an N layer 28 which is made n-type by diffusing phosphorus (P) as an impurity, for example, are sequentially provided from the lower side to the upper side. The upper surface of the N layer 28 is the light receiving surface 14 and functions as an emitter layer through which light is incident. This N layer 28 has an impurity concentration of, for example, 5 × 10 19 to 1 × 10 17 cm −3 and a concentration of 0.6 to 10 μm.
Of thickness.

【００１４】前記フィルタ１８および上記受光面１４を
通して太陽光が入射させられることにより発生した電子
対を構成する正電荷および負電荷は、Ｐ層２６およびＮ
層２８へそれぞれ移動させられ、Ｎ層２８とＰ層２６と
の間のＰＮ接合を境として起電力が発生させられる。こ
れにより、底部電極２１が正電極として機能し、上部電
極２２が負電極として機能する。Positive charges and negative charges constituting an electron pair generated by sunlight entering through the filter 18 and the light receiving surface 14 are converted into a P layer 26 and an N layer.
Each of them is moved to the layer 28, and an electromotive force is generated at a PN junction between the N layer 28 and the P layer 26. Thereby, the bottom electrode 21 functions as a positive electrode, and the upper electrode 22 functions as a negative electrode.

【００１５】図４は上記太陽電池セル１６の平面図であ
り、集光ミラー１２の集光面が部分円筒面である場合に
用いられる上部電極２２のパターン形状の一例を詳しく
示している。この上部電極２２は、矩形の受光面１４の
４辺のうち１対の長辺に対応する長側縁と一方の短辺に
対応する１つの短側縁とに沿った比較的太いＵ字状の導
体部３２と、そのＵ字状の導体部３２のうちの上記長側
縁に対応する互いに平行な部分から短辺に平行に一定間
隔でそれぞれ突き出された複数本の比較的細い細線部３
４とから構成されている。この細線部３４は、受光面１
４の短辺方向の幅の１／４に相当する中央領域Ａにおい
て、他の領域よりも配置本数の密度が１／３とされてい
る。この中央領域Ａが他の領域に比較して集光ミラー１
２による１軸集光にて高い集光照度（たとえば５０倍の
集光）で照射されるようになっており、たとえば図２の
集光照度の分布が上記短辺方向において形成される。本
実施例では、上記のように、細線部３４が、受光面１４
の短辺方向の幅の１／４に相当する中央領域Ａにおい
て、他の領域よりも配置本数の密度が１／３とされてい
る上部電極２２が、受光面１４の中央領域Ａに、他の領
域に比較して電子および正孔の再結合を減少させる再結
合減少手段に対応している。上部電極２２との界面では
結晶格子が歪むことによりキャリヤすなわち電子および
正孔が滞留し易く、再結合の確率が急増する傾向となる
ので、上部電極２２の配置本数の密度が他の領域よりも
１／３とされることにより再結合の確率が大幅に減少さ
せられているのである。FIG. 4 is a plan view of the solar cell 16, showing in detail an example of the pattern shape of the upper electrode 22 used when the light-collecting surface of the light-collecting mirror 12 is a partial cylindrical surface. The upper electrode 22 has a relatively thick U-shape along a long side edge corresponding to a pair of long sides and one short side edge corresponding to one short side among four sides of the rectangular light receiving surface 14. And a plurality of relatively thin thin line portions 3 protruding at regular intervals in parallel with the short sides from mutually parallel portions of the U-shaped conductor portion 32 corresponding to the long side edges.
And 4. This thin line portion 34 is
In the central region A corresponding to １ ／ of the width in the short side direction of No. 4, the density of the arrangement number is set to １ ／ compared to the other regions. This central area A is different from the other areas in that the focusing mirror 1
2 is used to irradiate with high condensing illuminance (for example, 50 times condensing), and for example, the distribution of condensing illuminance of FIG. 2 is formed in the short side direction. In this embodiment, as described above, the thin line portion 34 is
In the central region A corresponding to 1/4 of the width in the short side direction of the upper electrode 22, the upper electrode 22 whose density of the number of arrangements is 1/3 that of the other regions is located in the central region A of the light receiving surface 14, Corresponds to recombination reducing means for reducing the recombination of electrons and holes as compared with the region. At the interface with the upper electrode 22, since the crystal lattice is distorted, carriers, that is, electrons and holes tend to stagnate, and the probability of recombination tends to increase sharply. By making it 1/3, the probability of recombination is greatly reduced.

【００１６】上記の中央領域Ａでは、細線部３４の配置
本数の密度が１／３とされることにより単位面積当たり
の再結合電流すなわち光子の入射により発生させられた
１対の電子および正孔が再び結合することによる電流減
少分が３０％程度減少させられるので、図５および図６
に示すように、従来よりも高い電流密度および発生電力
が得られる。図５および図６において、１点鎖線は、上
記細線部３４の配置本数の密度を全面において一様とし
た太陽電池セルに対して厳密な光学系（したがって工業
的ではない）を用いて完全に一様な集光照射を行った場
合を示し、２点鎖線は、図７と同様に上記細線部３４の
配置本数の密度を全面において一様とした太陽電池セル
に対して前述の集光ミラー１２を用いて集光むらのある
状態で照射した従来の場合を示し、実線は、上述の実施
例の太陽電池セル１６に対して前述の集光ミラー１２を
用いて集光むらのある状態で照射した場合を示してい
る。発電効率で言えば、実線に示す本実施例の場合は１
２．９％を示し、この値は２点鎖線に示す従来の場合の
値（１２．３％）を上まわり、１点鎖線に示す全面均一
照射の場合の値（１３．９％）に近接した値となってい
る。In the central area A, the recombination current per unit area, that is, a pair of electrons and holes generated by the incidence of photons, is reduced by reducing the density of the number of the thin wire portions 34 to 1/3. 5 and FIG. 6 because the amount of current decrease due to the reconnection of the two is reduced by about 30%.
As shown in (1), a higher current density and higher generated power than before can be obtained. In FIGS. 5 and 6, the alternate long and short dash line is completely formed by using a strict optical system (thus, not industrial) for a solar cell in which the density of the number of the thin line portions 34 is uniform over the entire surface. The case where uniform condensing irradiation is performed is shown, and the two-dot chain line indicates the above-mentioned condensing mirror for a solar cell in which the density of the number of the thin line portions 34 is uniform over the entire surface, as in FIG. 12 shows a conventional case in which irradiation is performed in a state of uneven light collection, and a solid line indicates a state in which unevenness of light collection is performed using the above-described light collecting mirror 12 with respect to the solar cell 16 of the above-described embodiment. The case where irradiation was performed is shown. In terms of power generation efficiency, in the case of this embodiment shown by the solid line, 1
2.9%, which exceeds the conventional value (12.3%) shown by the two-dot chain line and is close to the value (13.9%) for the entire surface uniform irradiation shown by the one-dot chain line. Value.

【００１７】上述のように、本実施例の太陽電池セル１
６によれば、受光面１４の中央領域Ａに配置される櫛型
の上部電極２２の細線部３４のピッチをその他の領域に
比較して３倍程度に大きくし、配置本数の密度を１／３
程度に少なくした再結合減少手段が設けられているの
で、上記中央領域Ａにおける再結合電流が少なくなって
上記他の領域で発生した電流を食うことが少なくなり、
負荷接続時の発電効率が高められる。As described above, the solar cell 1 of the present embodiment
According to No. 6, the pitch of the fine line portions 34 of the comb-shaped upper electrode 22 arranged in the central region A of the light receiving surface 14 is increased to about three times as compared with other regions, and the density of the arrangement number is reduced to 1 /. 3
Since the recombination reducing means reduced to the extent is provided, the recombination current in the central region A is reduced, and the current generated in the other region is less consumed,
The power generation efficiency when the load is connected is increased.

【００１８】次に、本発明の他の実施例を説明する。な
お、以下の説明において前述の実施例と共通する部分に
は同一の符号を付して説明を省略する。Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

【００１９】本実施例の太陽電池セル３６は、図７に示
すように、図４の実施例と比較して、上部電極２２の細
線部３４のピッチが受光面１４の中央領域Ａと他の領域
とにおいて同じ配置本数密度とされているが、その中央
領域ＡにおけるＮ層（エミッタ層）２８内の不純物濃度
が他の領域の値たとえば５×１０19cm-3に比較して低い
値たとえば１×１０18cm-3とされると同時に、中央領域
Ａにおける受光面１４からＮ層２８とＰ層２６との間の
ＰＮ接合までの深さが他の領域に比較して大きく形成さ
れている。As shown in FIG. 7, in the solar cell 36 of this embodiment, as compared with the embodiment of FIG. Although the density of the arrangement number is the same in the region, the impurity concentration in the N layer (emitter layer) 28 in the central region A is lower than the value in other regions, for example, 5 × 10 19 cm −3 , for example. At the same time as 1 × 10 18 cm −3 , the depth from the light receiving surface 14 in the central region A to the PN junction between the N layer 28 and the P layer 26 is formed larger than in other regions. I have.

【００２０】上記太陽電池セル３６のＮ層２８の不純物
濃度は、次のような拡散工程により形成される。たとえ
ば、先ず、受光面１４の幅方向寸法の１／５程度以外の
領域を酸化膜でマスクした後、塩化ホスホリル（ＰＯＣ
ｌ3 ）および酸素・窒素混合ガスを導入しながら８１０
℃で１時間燐（Ｐ）を拡散すると同時に、表面に酸化膜
を形成する。次に、受光面１４の幅方向寸法１／５程度
以外の領域の酸化膜（マスク）を除去した後に、再び塩
化ホスホリル（ＰＯＣｌ3 ）を導入しながら８５０℃で
３０分燐（Ｐ）を拡散する。これにより、中央領域Ａ以
外の領域で不純物濃度が高くされる。また、中央領域Ａ
では、８５０℃で３０分の加熱により燐（Ｐ）がさらに
基板内部２６へ深く拡散させられることにより、不純物
濃度が低く、しかも受光面１４からＰＮ接合までの深さ
が他の領域よりも深い接合が形成される。The impurity concentration of the N layer 28 of the solar cell 36 is formed by the following diffusion process. For example, first, after masking an area other than about 1/5 of the width dimension of the light receiving surface 14 with an oxide film, phosphoryl chloride (POC
l 3 ) and 810 while introducing a mixed gas of oxygen and nitrogen.
At the same time, phosphorus (P) is diffused at a temperature of 1 ° C. for one hour, and at the same time, an oxide film is formed on the surface. Next, after removing the oxide film (mask) in a region other than about 1/5 in the width direction of the light receiving surface 14, phosphorus (P) is diffused at 850 ° C. for 30 minutes while introducing phosphoryl chloride (POCl 3 ) again. I do. Thereby, the impurity concentration is increased in regions other than the central region A. Also, the central area A
In this case, phosphorus (P) is further diffused deep into the substrate inside 26 by heating at 850 ° C. for 30 minutes, so that the impurity concentration is low and the depth from the light receiving surface 14 to the PN junction is deeper than other regions. A bond is formed.

【００２１】Ｎ層（エミッタ層）２８内において中央領
域Ａでは不純物拡散濃度が他の領域よりも低くされ且つ
中央領域Ａだけ受光面１４からＰＮ接合までの深さが他
の領域よりも深い接合が形成されていることから、その
中央領域Ａにおける再結合電流が抑制されている。すな
わち、半導体中の不純物濃度が高い領域ほどキャリヤが
滞留し易くなって再結合の確率が急増するが、中央領域
Ａでは不純物拡散濃度が他の領域よりも低くされ且つ中
央領域Ａだけ受光面１４からＰＮ接合までの深さが深い
接合が形成されているので、電子および正孔を分離して
各電極２２および２１へ駆動する接合に伴う内部電界が
再結合頻度の高い表面より離れるため、再結合の確率が
低下する。さらに、Ｎ層（エミッタ層）２８の厚みが厚
くされているので、出力電流が通過するときのＮ層（エ
ミッタ層）２８の抵抗が低くなり、この点においても再
結合の確率が低下する。したがって、図８および図９に
示すように、従来よりも高い電流密度および発生電力が
得られる。図８および図９において、１点鎖線は、上記
細線部３４の配置本数の密度を全面において一様とした
太陽電池セルに対して厳密な光学系（したがって工業的
ではない）を用いて完全に一様な集光照射を行った場合
を示し、２点鎖線は、図７と同様に上記細線部３４の配
置本数の密度を全面において一様とした太陽電池セルに
対して前述の集光ミラー１２を用いて集光むらのある状
態で照射した従来の場合を示し、実線は、上述の実施例
の太陽電池セル３６に対して前述の集光ミラー１２を用
いて集光むらのある状態で照射した場合を示している。
発電効率で言えば、実線に示す本実施例の場合は１３．
０％が得られた。In the N layer (emitter layer) 28, the impurity diffusion concentration is lower in the central region A than in the other regions, and the junction from the light receiving surface 14 to the PN junction is deeper in the central region A than in the other regions. Are formed, the recombination current in the central region A is suppressed. That is, the higher the impurity concentration in the semiconductor, the more the carrier tends to stagnate and the probability of recombination increases sharply. However, in the central region A, the impurity diffusion concentration is lower than in other regions, and only the central region A has a light receiving surface 14. Is formed, the internal electric field associated with the junction that separates electrons and holes and drives each of the electrodes 22 and 21 is separated from the surface where recombination frequency is high. The probability of binding is reduced. Further, since the thickness of the N layer (emitter layer) 28 is increased, the resistance of the N layer (emitter layer) 28 when an output current passes is reduced, and the recombination probability is also reduced in this regard. Therefore, as shown in FIG. 8 and FIG. 9, a higher current density and higher generated power can be obtained as compared with the related art. In FIGS. 8 and 9, the alternate long and short dash line is completely formed using a strict optical system (thus, not industrial) for a solar cell in which the density of the number of the thin line portions 34 is uniform over the entire surface. The case where uniform condensing irradiation is performed is shown, and the two-dot chain line indicates the above-mentioned condensing mirror for a solar cell in which the density of the number of the thin line portions 34 is uniform over the entire surface, as in FIG. 12 shows a conventional case in which irradiation is performed in a state of uneven light collection, and a solid line indicates a state in which unevenness of light collection is performed using the above-described light collecting mirror 12 with respect to the solar cell 36 of the above-described embodiment. The case where irradiation was performed is shown.
In terms of power generation efficiency, in the case of the present embodiment shown by a solid line, 13.
0% was obtained.

【００２２】上述のように、本実施例の太陽電池セル３
６によれば、Ｎ層（エミッタ層）２８内において受光面
１４の中央領域Ａの不純物密度が他の領域の密度に比較
して低くされ、且つその中央領域Ａの受光面１４からＰ
Ｎ接合までの深さが他の領域よりも深くした再結合減少
手段が設けられているので、上記中央領域Ａにおける再
結合電流が少なくなって上記他の領域で発生した電流を
食うことが少なくなり、負荷接続時の発電効率が高めら
れる。As described above, the solar cell 3 of the present embodiment
According to 6, in the N layer (emitter layer) 28, the impurity density of the central region A of the light receiving surface 14 is made lower than the density of the other regions, and P
Since the recombination reducing means whose depth to the N junction is deeper than the other region is provided, the recombination current in the central region A is reduced, and the current generated in the other region is less consumed. Therefore, the power generation efficiency when the load is connected is improved.

【００２３】以上、本発明の一実施例を図面を参照して
詳細に説明したが、本発明は、更に別の態様でも実施さ
れる。While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in still another embodiment.

【００２４】例えば、前述の実施例の太陽電池セル１６
では、その受光面１４の中央領域Ａに配置される櫛型の
上部電極２２の細線部３４のピッチをその他の領域に比
較して３倍程度に大きくし、配置本数の密度を１／３程
度に少なくした再結合減少手段が設けられていたが、上
記受光面１４の中央領域Ａにおいて櫛型の上部電極２２
の細線部３４の被覆率またはその細線部３４の幅を他の
領域に比較して小さくした再結合減少手段が設けられて
もよい。このようにしても、上記中央領域Ａにおける再
結合電流が少なくなって上記他の領域で発生した電流を
食うことが少なくなり、負荷接続時の発電効率が高めら
れる。For example, the solar cell 16 of the above-described embodiment
In this case, the pitch of the fine line portions 34 of the comb-shaped upper electrode 22 arranged in the central area A of the light receiving surface 14 is increased about three times as compared with other areas, and the density of the arrangement number is reduced to about ３. Although the recombination reducing means is provided in the central area A of the light receiving surface 14, the comb-shaped upper electrode 22
Recombination reducing means may be provided in which the coverage of the thin line portion 34 or the width of the thin line portion 34 is made smaller than that of other regions. Even in this case, the recombination current in the central region A is reduced, and the current generated in the other region is less consumed, and the power generation efficiency when the load is connected is increased.

【００２５】また、前述の実施例の太陽電池セル３６で
は、Ｎ層（エミッタ層）２８内において受光面１４の中
央領域Ａの不純物密度が他の領域の密度に比較して低く
され、且つその中央領域Ａの受光面１４からＰＮ接合ま
での深さが他の領域よりも深くした再結合減少手段が設
けられていたが、それに代えて、Ｎ層（エミッタ層）２
８内において受光面１４の中央領域Ａの不純物密度が他
の領域の密度に比較して低くされた再結合減少手段や、
中央領域Ａの受光面１４からＰＮ接合までの深さが他の
領域よりも深くした再結合減少手段が設けられてもよ
い。このようにしれも、上記中央領域Ａにおける再結合
電流が少なくなって上記他の領域で発生した電流を食う
ことが少なくなり、負荷接続時の発電効率が高められ
る。In the solar cell 36 of the above-described embodiment, the impurity density of the central region A of the light receiving surface 14 in the N layer (emitter layer) 28 is made lower than the density of the other regions. Although recombination reducing means is provided in which the depth from the light receiving surface 14 of the central region A to the PN junction is deeper than other regions, an N layer (emitter layer) 2 is provided instead.
8, recombination reducing means in which the impurity density of the central region A of the light receiving surface 14 is lower than that of the other regions,
Recombination reducing means may be provided in which the depth from the light receiving surface 14 of the central region A to the PN junction is deeper than other regions. In this case, the recombination current in the central region A is reduced, so that the current generated in the other region is less consumed, and the power generation efficiency when the load is connected is increased.

【００２６】また、前述の太陽電池セル１６、３６に設
けられた再結合減少手段、および上記複数種類の再結合
減少手段のうちの２つ以上が組み合わされた再結合減少
手段が用いられてもよい。Further, the recombination reducing means provided in the solar cells 16 and 36 and the recombination reducing means obtained by combining two or more of the plurality of types of recombination reducing means may be used. Good.

【００２７】また、前述の実施例の太陽電池セル１６、
３６では、再結合減少手段が中央領域Ａに設けられてい
たが、受光面１４の幅方向の中央である必要はない。た
とえば、受光面１４の長手方向の中央部とか端部であっ
てもよい。要するに、他の領域に比較して集光ミラー１
２により高い集光照度で照射される領域であればよいの
である。Further, the solar cell 16 of the above-described embodiment,
In 36, the recombination reducing means is provided in the central region A, but need not be at the center of the light receiving surface 14 in the width direction. For example, it may be a central portion or an end portion of the light receiving surface 14 in the longitudinal direction. In short, the condensing mirror 1 is compared with other regions.
It only has to be a region irradiated with the higher converging illuminance than the region 2.

【００２８】また、前述の実施例の太陽電池セル１６に
おいて、エミッタ層であるＮ層２８は不純物として燐
（Ｐ）が拡散されることによりｎ型半導体とされ、Ｐ層
２６不純物としてホウ素（Ｂ）が拡散されることにより
ｐ型半導体とされていたが、逆にエミッタ層がｐ型半導
体とされ、その下層がｎ型半導体とされていても差し支
えない。In the solar cell 16 of the above-described embodiment, the N layer 28 as the emitter layer is made an n-type semiconductor by diffusion of phosphorus (P) as an impurity, and the P layer 26 is boron (B) as an impurity. ) Is diffused into a p-type semiconductor, but the emitter layer may be a p-type semiconductor and the underlying layer may be an n-type semiconductor.

【００２９】また、前述の実施例の集光式太陽光発電装
置１０では、集光器として集光ミラー１２が用いられて
いたが、集光レンズなどであってもよい。Further, in the concentrator photovoltaic power generator 10 of the above-described embodiment, the converging mirror 12 is used as a concentrator, but a converging lens or the like may be used.

【００３０】また、前述の集光ミラー１２の集光面に
は、球面、放物面、部分円筒面などの種々の形状が用い
られる。Various shapes such as a spherical surface, a paraboloid, and a partial cylindrical surface are used for the light-collecting surface of the light-collecting mirror 12 described above.

【００３１】その他、一々例示はしないが、本発明はそ
の趣旨を逸脱しない範囲で種々変更を加え得るものであ
る。Although not specifically exemplified, the present invention can be variously modified without departing from the spirit thereof.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の一実施例の集光式太陽光発電装置の要
部構成を説明する図である。FIG. 1 is a diagram illustrating a main configuration of a concentrating solar power generation device according to an embodiment of the present invention.

【図２】図１の太陽電池セルにおける太陽光の不均一照
射を説明する分布図である。FIG. 2 is a distribution diagram illustrating uneven irradiation of sunlight in the solar cell of FIG.

【図３】図１の太陽電池セルの構成を説明する断面図で
ある。FIG. 3 is a cross-sectional view illustrating a configuration of the solar cell of FIG.

【図４】図１の太陽電池セルの上部電極を説明する平面
図である。FIG. 4 is a plan view illustrating an upper electrode of the solar cell of FIG.

【図５】図１の太陽電池セルの電圧−電流特性を、均一
照射した太陽電池セルおよび従来の太陽電池セルと対比
して説明する図である。FIG. 5 is a diagram illustrating voltage-current characteristics of the solar cell of FIG. 1 in comparison with a uniformly irradiated solar cell and a conventional solar cell.

【図６】図１の太陽電池セルの電圧−発生電力特性を、
均一照射した太陽電池セルおよび従来の太陽電池セルと
対比して説明する図である。FIG. 6 shows a voltage-generated power characteristic of the solar cell of FIG.
FIG. 4 is a diagram for explaining in comparison with a uniformly irradiated solar cell and a conventional solar cell.

【図７】本発明の他の実施例における太陽電池セルを説
明する平面図である。FIG. 7 is a plan view illustrating a solar cell according to another embodiment of the present invention.

【図８】図７の太陽電池セルの電圧−電流特性を、均一
照射した太陽電池セルおよび従来の太陽電池セルと対比
して説明する図である。FIG. 8 is a diagram for explaining voltage-current characteristics of the solar cell of FIG. 7 in comparison with a uniformly irradiated solar cell and a conventional solar cell.

【図９】図７の太陽電池セルの電圧−発生電力特性を、
均一照射した太陽電池セルおよび従来の太陽電池セルと
対比して説明する図である。9 shows the voltage-generated power characteristics of the solar cell of FIG.
FIG. 4 is a diagram for explaining in comparison with a uniformly irradiated solar cell and a conventional solar cell.

【図１０】従来の太陽電池セルにおいて、集光照度すな
わち不均一照射における出力電流および電力を一様照射
の場合と比較して示す図である。FIG. 10 is a diagram showing the condensed illuminance, that is, the output current and power in non-uniform irradiation in a conventional solar cell, in comparison with the case of uniform irradiation.

【図１１】従来の太陽電池セルにおいて、集光照度分布
の半値幅の比（半値幅／集光発電用太陽電池セルの受光
面の開口幅）に対する発電効率を集光倍率１０乃至５０
の範囲を示す図である。FIG. 11 is a graph showing the relationship between the ratio of the half-width of the concentrated illuminance distribution (half-width / opening width of the light-receiving surface of the solar cell for concentrating power generation) to the power-generating efficiency of the conventional solar cell.
FIG.

【符号の説明】[Explanation of symbols]

１０：集光式太陽光発電装置 １２：集光ミラー（集光器） １４：受光面 １６、３６：集光発電用太陽電池セル ３４：細線部（再結合減少手段） Ａ：中央領域（所定の領域） 10: Concentrating solar power generation device 12: Condensing mirror (concentrator) 14: Light receiving surface 16, 36: Concentrating solar cell 34: Thin line portion (recombination reducing means) A: Central region (predetermined) Area)

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】 太陽光を受けるための受光面を備え、該
受光面の所定の領域ほど高い集光照度で照射される集光
発電用太陽電池セルにおいて、 前記受光面の所定の領域に、他の領域に比較して電子お
よび正孔の再結合を減少させる再結合減少手段を設けた
ことを特徴とする集光発電用太陽電池セル。1. A concentrating power generation solar cell comprising: a light receiving surface for receiving sunlight; and a predetermined area of the light receiving surface is irradiated with a higher condensed illuminance. And a recombination reducing means for reducing recombination of electrons and holes as compared with the region (1). 【請求項２】 前記集光発電用太陽電池セルは、所定の
間隔を隔てて互いに平行な複数本の導体を含む櫛型電極
を受光面に備えたものであり、 前記再結合減少手段は、該受光面の前記所定の領域に配
置される櫛型電極の被覆率または該櫛型電極の幅を前記
他の領域に比較して小さくし、或いは該櫛型電極のピッ
チを該他の領域に比較して大きくしたものである請求項
１の集光発電用太陽電池セル。2. The photovoltaic cell for concentrating power generation includes a comb-shaped electrode including a plurality of conductors parallel to each other at a predetermined interval on a light-receiving surface. The coverage of the comb-shaped electrode or the width of the comb-shaped electrode arranged in the predetermined area of the light-receiving surface is made smaller than that of the other area, or the pitch of the comb-shaped electrode is reduced to the other area. The solar cell for concentrating power generation according to claim 1, which is enlarged in comparison. 【請求項３】 前記集光発電用太陽電池セルは、不純物
が拡散されることによりｎ型或いはｐ型半導体とされた
エミッタ層を前記受光面側に備えたものであり、 前記再結合減少手段は、該受光面の前記所定の領域にお
ける不純物濃度を、前記他の領域に比較して低くしたも
のである請求項１または２の集光発電用太陽電池セル。3. The photovoltaic cell for concentrating power generation includes an emitter layer, which is made of an n-type or a p-type semiconductor by diffusion of an impurity, on the light-receiving surface side. The solar cell for concentrating power generation according to claim 1 or 2, wherein an impurity concentration in the predetermined region of the light receiving surface is lower than that of the other region. 【請求項４】 前記集光発電用太陽電池セルは、その受
光面から所定の深さ位置にＰＮ接合を備えたものであ
り、 前記再結合減少手段は、該受光面の前記所定の領域にお
ける受光面からのＰＮ接合の深さ位置を、前記他の領域
に比較して大きくしたものである請求項１乃至３のいず
れかの集光発電用太陽電池セル。4. The photovoltaic cell for concentrating power generation includes a PN junction at a predetermined depth position from a light receiving surface thereof, and the recombination reducing unit includes a PN junction in the predetermined region of the light receiving surface. The solar cell for concentrating power generation according to any one of claims 1 to 3, wherein a depth position of the PN junction from the light receiving surface is larger than that of the other region.
JP25559799A 1999-09-09 1999-09-09 Solar battery cell for light convergence power generation Pending JP2001085714A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP25559799A JP2001085714A (en) 1999-09-09 1999-09-09 Solar battery cell for light convergence power generation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP25559799A JP2001085714A (en) 1999-09-09 1999-09-09 Solar battery cell for light convergence power generation

Publications (1)

Publication Number Publication Date
JP2001085714A true JP2001085714A (en) 2001-03-30

Family

ID=17280944

Family Applications (1)

Application Number Title Priority Date Filing Date
JP25559799A Pending JP2001085714A (en) 1999-09-09 1999-09-09 Solar battery cell for light convergence power generation

Country Status (1)

Country Link
JP (1) JP2001085714A (en)

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