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所属 |
工学教育研究部 工学科電気電子システムプログラム担当 |
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職名 |
准教授 |
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Sato D., Honda S., Tanimoto T., Lee B., Geißler S., Miyashita Y., Yamada N.
Solar Energy Materials and Solar Cells 292 2025年10月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Solar Energy Materials and Solar Cells
The rapid deployment of photovoltaic (PV) systems in diverse applications is crucial for facilitating the transition to a carbon-neutral society. Vehicle-integrated PV (VIPV) technology shows promise in reducing CO<inf>2</inf> emissions within the transportation sector. However, several challenges must be addressed in the design and fabrication of VIPV modules, including compatibility with 3D curved vehicle bodies and durability under various mechanical loads encountered in operating environments—such as torsion of the targeted installation bodies—which differ from the requirements of conventional static PV modules. This study quantitatively analyzes the mechanical strength (bending and torsion) of tunnel oxide passivated contact (TOPCon) crystalline silicon solar cells cut using thermal laser separation (TLS) technology through comparison with identical solar cells cut using laser scribing and cleaving (LSC) technology. Ball-on-ring and four-line bend tests are conducted on state-of-the-art TOPCon half-cells, and their stress characteristics under spherical surface deformation are evaluated through finite element method simulations, revealing the optimal cell size (182 mm × 45.5 mm, aspect ratio = 4) for integration into a spherical surface with curvature radius of 1 m. In addition, the torsional strength of the TOPCon half-cells integrated into a polymer-based submodule is experimentally assessed, and the mechanism of crack initiation is identified. The results demonstrate the superior durability of TLS-cut cells against bending and torsion loads compared with LSC-cut cells, indicating their advantages for VIPV applications.
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Sato D., Kobayashi H., Masuda T., Araki K., Miyashita Y., Yamada N.
Solar Energy Materials and Solar Cells 279 2025年1月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Solar Energy Materials and Solar Cells
The rapid deployment of photovoltaic (PV) devices through diversified applications is essential for advancing toward a zero-carbon society. The development of three-dimensional (3D) curved PV modules is crucial for new PV applications, such as vehicle-integrated PV systems. However, commonly used solar cell materials, particularly crystalline Si (c-Si), are inherently brittle and fragile. These characteristics present significant challenges for their integration onto 3D curved surfaces, thereby restricting the expansion of the PV coverage area. This study proposes a structural design methodology for 3D curved PV modules, incorporating flexural tests of solar cells, mechanical stress analysis across various cell sizes and radii of curvature (R), and evaluation of the risk of cell breakage when shaped to the targeted 3D curved geometries. Practical-scale 3D curved PV modules, featuring a 3-inch c-Si cell array with isotropic R values of 1 m or 1.5 m, have been successfully produced and characterized using electroluminescence and current–voltage characteristic measurements. The solar cell placement design has been implemented on an actual automobile body, identifying suitable surfaces for c-Si cell integration without the risk of breakage. The results demonstrate that reducing the cell size can enhance the total installed cell area on the automobile's body.
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Sato D., Masuda T., Araki K., Yamaguchi M., Okumura K., Sato A., Tomizawa R., Yamada N.
Communications Materials 2 ( 1 ) 2021年12月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Communications Materials
Stretchable photovoltaics are emerging power sources for collapsible electronics, biomedical devices, and buildings and vehicles with curved surfaces. Development of stretchable photovoltaics are crucial to achieve rapid growth of the future photovoltaic market. However, owing to their rigidity, existing thin-film solar cells based predominantly on silicon, compound semiconductors, and perovskites are difficult to apply to 3D curved surfaces, which are potential real-world candidates. Herein, we present a stretchable micro-scale concentrator photovoltaic module with a geometrical concentration ratio of 3.5×. When perfectly fitted on a 3D curved surface with a sharp curvature, the prototype module achieves an outdoor power conversion efficiency of 15.4% and the daily generated electricity yield improves to a maximum of 190% relative to a non-concentration stretchable photovoltaic module. Thus, this module design enables high areal coverage on 3D curved surfaces, while generating a higher electricity yield in a limited installation area.
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Araki K., Ota Y., Saiki H., Tawa H., Nishioka K., Sato D., Yamaguchi M.
Aip Conference Proceedings 2298 2020年11月
掲載種別：研究論文（学術雑誌） 出版者・発行元：Aip Conference Proceedings
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