Araki Kenji

写真a

Affiliation

Engineering educational research section Electrical and Electronic Engineering Program

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Degree 【 display / non-display 】

  • Doctor (Engineering) ( 2005.3   Nagoya Institute of Technology )

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Papers 【 display / non-display 】

  • 3D Solar Irradiance Model for Non-Uniform Shading Environments Using Shading (Aperture) Matrix Enhanced by Local Coordinate System Reviewed

    Araki K., Ota Y., Nagaoka A., Nishioka K.

    Energies   16 ( 11 )   2023.6

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    Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Energies  

    Building-integrated photovoltaics (BIPVs) and vehicle-integrated photovoltaics (VIPVs) receive solar irradiance through non-uniform shading objects. Standard scalar calculations cannot accurately determine the solar irradiance of BIPV and VIPV systems. This study proposes a matrix model using an aperture matrix to accurately calculate the horizontal and vertical planes affected by non-uniform shading objects. This can be extended to the solar irradiance on a VIPV by applying a local coordinate system. The 3D model is validated by a simultaneous measurement of five orientations (roof and four sides, front, left, tail, and right) of solar irradiance on a car body. An accumulated logistic function can approximate the shading probability. Furthermore, the combined use of the 3D solar irradiance model is effective in assessing the energy performance of solar electric vehicles in various zones, including buildings, residential areas, and open spaces. Unlike standard solar energy systems, the energy yield of a VIPV is affected by the shading environment. This, in turn, is affected mainly by the location of vehicle travel or parking in the city rather than by the climate zones of the city.

    DOI： 10.3390/en16114414

    Scopus

  • How did the knowledge of CPV contribute to the standardization activity of VIPV? Reviewed

    Araki K., Ji L., Kelly G., van der Ham A., Agudo E., Antón I., Baudrit M., Carr A., Herrero R., Kurtz S., Liu Z., Pravettoni M., Ota Y., Tobita H., Yoon S., Yoshita M., Yamaguchi M., Nishioka K.

    AIP Conference Proceedings   2298   2020.11

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Conference Proceedings  

    © 2020 American Institute of Physics Inc.. All rights reserved. The standardization of VIPV (Vehicle-integrated photovoltaic) has been driven by the international discussion among scientists and engineers, from photovoltaic research, photovoltaic industries, automobile and other industries, and testing laboratories. Since the VIPV is not flat and fixed installation, as well as a wide variety of designs, the knowledge of CPV (Concentrator Photovoltaic) technology, has been useful for developing testing technologies. This paper took two examples in the performance testing and the test for the tolerance for the partial/dynamic shading, utilizing various techniques exclusively used in CPV technologies.

    DOI： 10.1063/5.0032997

    Scopus

  • Super-multi-junction solar cells - Device configuration with the potential for more than 50% annual energy conversion efficiency (CPV) Reviewed

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

    AIP Conference Proceedings   2298   2020.11

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Conference Proceedings  

    © 2020 American Institute of Physics Inc.. All rights reserved. The performance of CPV is sensitive to the spectrum change. Several previous works have been published on the sensitivity of multi-junction cells to airmass variations as well as works on band gap tuning and optimization of multi-junction stacks under concentrated radiation in various locations. Such a variety of atmospheric conditions, airmass as well as climate (quality of direct sunlight) are dynamic and cannot be controlled by the product design. All we can do is to customize the design by locations (not capable of dynamic variation) or inventing a robust device configuration against a dynamic change of atmospheric conditions (also effective to regional variation). Enhancing a luminescent coupling is useful to suppress the spectrum mismatching loss inherent to outdoor CPV installation. The configuration of the solar cell with 100 % of the recycling of the surplus photon energy for compensating spectrum mismatching is called an SMJ solar cell (super-multi-junction solar cell). The advantage of the SMJ solar cells in non-concentrating fixed sloped angle installation was intensively analyzed in the previous works. However, that of CPV was only investigated under the combination of the worst-case atmospheric parameter distributions, and not under the realistic spectrum variations, so that the calculation result was too extreme. This paper intended to fill the missing stone, by updating a previous result on CPV modeled under the combination of the worst-case variations of atmospheric conditions in the worst locations for CPV, by the realistic fluctuation pattern of meteorological parameters and climate using the intensive analysis that was done to the non-concentration installation (fixed installation). The SMJ was also confirmed valid to CPV under the dynamic fluctuation of the direct solar resources. Different from the non-concentrating operation, the normal CPV was found raising annual average outdoor efficiency under realistic atmospheric conditions simulated by the regional states in Miyazaki, Japan, up to six-junctions. This analysis also implies the bandgap design guideline for the robustness of the spectrum variation, trying to place the bandgap energy of the some of the sub-cells close to the water-absorption band (1.3 eV, 1.1 eV, and 0.89 eV).

    DOI： 10.1063/5.0032996

    Scopus

  • The outdoor field test and energy yield model of the four-terminal on si tandem PV module Reviewed

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

    Applied Sciences (Switzerland)   10 ( 7 )   2020.4

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Sciences (Switzerland)  

    © 2020 by the authors. 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： 10.3390/app10072529

    Scopus

  • Measurement and modeling of 3D solar irradiance for vehicle-integrated photovoltaic Reviewed

    Araki K., Ota Y., Yamaguchi M.

    Applied Sciences (Switzerland)   10 ( 3 )   2020.2

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Sciences (Switzerland)  

    © 2020 by the author. 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： 10.3390/app10030872

    Scopus

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Books 【 display / non-display 】

  • Recent and future trends in PV technology International journal

    Araki K., Beneking C., Faiman D., Gigliucci G., Paletta F.（ Role： Sole author）

    Energy from the Desert: Very Large Scale Photovoltaic Systems: Socio-economic, Financial, Technical and Environmental Aspects  2007.1  （ ISBN:9781849770064 ）

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    Language：Japanese

    DOI： 10.4324/9781849770064

    Scopus

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MISC 【 display / non-display 】

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Grant-in-Aid for Scientific Research 【 display / non-display 】

  • 曲面を有する太陽光パネルの計量法など工学体系構築

    Grant number：22K05006  2022.04 - 2027.03

    独立行政法人日本学術振興会  科学研究費補助金  基盤研究(C)

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    Authorship：Principal investigator 

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