太田 靖之 (オオタ ヤスユキ)

OTA Yasuyuki

写真a

職名

助教

 

論文 【 表示 / 非表示

  • Evaluation of a Sabatier Reaction Utilizing Hydrogen Produced by Concentrator Photovoltaic Modules under Outdoor Conditions

    SoeHtet Wai, Yasuyuki Ota, Masakazu Sugiyama, Kensuke Nishioka

    Applied Sciences   10 ( 9 ) 3144   2020年04月  [査読有り]

    共著

     概要を見る

    Power to gas (P2G) process chains have tremendous potential to enhance energy systems because of the capability of solar energy to convert solar radiation into electrical energy as well as the increasing use of specific gases as a means to store the resulting energy. Utilizing sunlight, photovoltaic systems are capable of producing useful gases such as hydrogen (H2) and methane (CH4). These gases are utilized in gas grids, transportation, and heavy industry. In employing a sunlight-derived gas, H2 production, by water disbanding, needs to be cost-effective with tremendous adaptability. New powerful solar to gas conversion system modules have been successfully carried out in the University of Miyazaki, Japan. These systems contain DC/DC converters and electrolyzer sets linked in parallel with efficient three concentrator photovoltaics (CPV). The performance of the solar to methane conversion process and power consumption analysis will be the focus of the current research. Efficiencies of 97.6% of CO2 to CH4 conversion and 13.8% for solar to methane on a clear sunny day were obtained by utilizing highly efficient CPV modules connected with multiple converters, electrochemical cells, and reactors fixed with Ni-based catalysts.

    DOI

  • The Outdoor Field Test and Energy Yield Model of the Four-Terminal on Si Tandem PV Module

    Kenji Araki, Hiroki Tawa, Hiromu Saiki, Yasuyuki Ota, Kensuke Nishioka, Masafumi Yamaguchi

    Applied Sciences   10 ( 7 ) 2529   2020年04月  [査読有り]

    共著

     概要を見る

    The outdoor field test of the 4-terminal on Si tandem photovoltaic module (specifically, InGaP/GaAs on Si) was investigated and a performance model, considering spectrum change affected by fluctuation of atmospheric parameters, was developed and validated. The 4-terminal on Si tandem photovoltaic module had about 40% advantage in seasonal performance loss compared with standard InGaP/GaAs/InGaAs 2-terminal tandem photovoltaic module. This advantage increases (subarctic zone < temperate zone < subtropical zone). The developed and validated model used an all-climate spectrum model and considered fluctuation of atmospheric parameters. It can be applied every type of on-Si tandem solar cells.

    DOI

  • Measurement and Modeling of 3D Solar Irradiance for Vehicle-Integrated Photovoltaic

    Kenji Araki,Yasuyuki Ota and Masafumi Yamaguchi

    Applied Sciences   10 ( 3 ) 872   2020年01月  [査読有り]  [招待有り]

    共著

     概要を見る

    The energy yield of vehicle-integrated photovoltaics (VIPV) differs from that of standard photovoltaics (PV). It is mainly by the difference of the solar irradiance onto the car roof and car bodies as well as its curved shape. Both meaningful and practical modeling and measurement of solar irradiance for VIPV need to be established, rather than the extension of the current technologies. The solar irradiance is modeled by a random distribution of shading objects and car orientation with the correction of the curved surface of the PV modules. The measurement of the solar irradiance onto the car roof and car body is done using five pyranometers in five local axes on the car for one year. The measured dynamic solar irradiance onto the car body and car roof is used for validation of the solar irradiance model in the car.

    DOI

  • Accurate Output Forecasting Method for Various Photovoltaic Modules Considering Incident Angle and Spectral Change Owing to Atmospheric Parameters and Cloud Conditions

    Hiroki Tawa, Hiromu Saiki, Yasuyuki Ota, Kenji Araki, Tatsuya Takamoto and Kensuke Nishioka

    Applied Sciences   10 ( 2 ) 703   2020年01月  [査読有り]

    共著

     概要を見る

    Because semiconductors absorb wavelengths dependent on the light absorption coefficient, photovoltaic (PV) energy output is affected by the solar spectrum. Therefore, it is necessary to consider the solar spectrum for highly accurate PV output estimation. Bird’s model has been used as a general spectral model. However, atmospheric parameters such as aerosol optical depth and precipitable water have a constant value in the model that only applies to clear days. In this study, atmospheric parameters were extracted using the Bird’s spectrum model from the measured global spectrum and the seasonal fluctuation of atmospheric parameters was examined. We propose an overcast spectrum model and calculate the all-weather solar spectrum from clear to overcast sky through linear combination. Three types of PV modules (fixed Si, two-axis tracking Si, and fixed InGaP/GaAs/InGaAs triple-junction solar cells) were installed at the University of Miyazaki. The estimated performance ratio (PR), which takes into account incident angle and spectral variations, was consistent with the measured PR. Finally, the energy yield of various PVs installed across Japan was successfully estimated.

    DOI

  • Super-multi-junction solar cells-device configuration with the potential for more than 50% annual energy conversion efficiency (non-concentration)

    Araki K., Ota Y., Saiki H., Tawa H., Nishioka K., Yamaguchi M.

    Applied Sciences (Switzerland)   9 ( 21 )   2019年11月  [査読有り]  [招待有り]

    共著

     概要を見る

    © 2019 by the authors. Licensee MDPI, Basel, Switzerland. The highest-efficiency solar cell in the efficiency race does not always give the best annual energy yield in real world solar conditions because the spectrum is always changing. The study of radiative coupling of concentrator solar cells implies that efficiency could increase by recycling the radiative recombination generated by the surplus current in the upper junction. Such a configuration is called a super-multi-junction cell. We expand the model in the concentrator solar cell to a non-concentrating installation. It is shown that this super-multi-junction cell configuration is robust and can keep maximum potential efficiency (50% in realistic spectrum fluctuation) for up to 10 junctions. The super-multi-junction cell is also robust in the bandgap engineering of each junction. Therefore, a future multi-junction may not be required for tuning the bandgap to match the standard solar spectrum, as well as relying upon artificial technologies such as epitaxial lift-off (ELO), wafer-bonding, mechanical-stacking, and reverse-growth, but merely uses upright and lattice-matching growth technologies. We present two challenging techniques; one is the optical cap layer that may be the directional photon coupling layer in the application of the photonics technologies, and another is the high-quality epitaxial growth with almost 100% radiative efficiency.

    DOI

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科研費(文科省・学振)獲得実績 【 表示 / 非表示

  • システム最適化した高効率集光型太陽電池水素生成機構の高精度コスト試算モデルの構築

    基盤研究(C)

    研究期間:  2018年  -  2021年03月 

研究発表 【 表示 / 非表示

  • Influence of Diffuse Light on Conversion Efficiency Measurement of 4-junction Solar Cells Under Real Concentrated Sunlight

    Shinya Honda, Yoshihito Imamatsu, Shogo Murayama, Hideo Teramoto, Yuki Nakamura, Ryota Jomen, Yoshiaki Ajima, Shu Takahashi, Tomoya Kamata, Shunsuke Hayashi, Naoki Saito, Yuichi Mikami, Masayoshi Kawahara, Yasuyuki Ota, Pan Dai, Shulong Lu, Shiro Uchida

    29th International Photovoltaic Science and Engineering Conference  (Xi'an, Shaanxi, China)  2019年11月  -  2019年11月   

  • A Spectrum- Energy Model for Annual Yield Estimation of 2-And 4-Terminal Tandem Solar Cells

    Hiroki Tawa, Hiromu Saiki, Yasuyuki Ota, Kenji Araki, Kohsuke Ueda, Tatsuya Takamoto, Masafumi Yamaguchi, Kensuke Nishioka

    29th International Photovoltaic Science and Engineering Conference  (Xi'an, Shaanxi, China)  2019年11月  -  2019年11月   

  • Verification of Accuracy in Spectrum-energy Model for Tandem Solar Cell

    Hiromu Saiki, Hiroki Tawa, Kenji Araki, Yasuyuki Ota, Kensuke Nishioka

    29th International Photovoltaic Science and Engineering Conference  (Xi'an, Shaanxi, China)  2019年11月  -  2019年11月   

  • Standardization Discussions for the Car-Roof PV - Starting Two Years Ago, and What We Have Achieved Since Then

    Kenji Araki, Liang Ji, George Kelly, Emilio Agudo, Ignacio Anton, Mathieu Baudrit, Anna Carr, Rebeca Herrero, Sarah Kurtz, Zhengxin Liu, Moritz Limpinsel, Zhonglin Lu, Mauro Pravettoni, Kensuke Nishioka, Yasuyuki Ota, Paul Robusto, Hiromi Tobita, Qian Wu, Zhenyu Wu, Sewang Yoon, Masahiro Yoshita, Masafumi Yamaguchi

    29th International Photovoltaic Science and Engineering Conference  (Xi'an, Shaanxi, China)  2019年11月  -  2019年11月   

  • Can We Break the 43% Limit of the Annual Average Efficiency (Non-concentration)?

    Kenji Araki, Daisuke Sato, Yasuyuki Ota, Kensuke Nishioka, Masafumi Yamaguchi

    29th International Photovoltaic Science and Engineering Conference  (Xi'an, Shaanxi, China)  2019年11月  -  2019年11月   

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