成果報告書詳細
管理番号20140000000801
タイトル*平成25年度中間年報 革新的太陽光発電技術研究開発(革新型太陽電池国際研究拠点整備事業) ポストシリコン超高効率太陽電池の研究開発(エピタキシャル成長技術)
公開日2015/4/15
報告書年度2013 - 2013
委託先名シャープ株式会社
プロジェクト番号P07015
部署名新エネルギー部
和文要約
英文要約Title: R&D on innovative Solar Cells (International Research Center for Innovative Solar Cell Program) “Research and Development of Post-silicon solar cells for ultra-high efficiencies (epitaxial technologies)” (FY2008-FY2014) FY2013 Annual Report

Development on inverted lattice mismatch triple junction cells composed of InGaP(1.88eV) top cell, GaAs(1.42eV) middle cell and InGaAs(0.98~1.00eV) bottom cell has been continued since FY2008 and a field test of concentrator systems has been started from FY 2012 in Arizona USA. During the investigation in FY2008-FY2012, 37.9% efficiency under 1sun was confirmed by National Institute of Advanced Industrial Science and Technology(AIST), and 44% efficiency was also confirmed under 400x~600x concentration ratio in house measurement. In April 2013 an official efficiency of 44.4% was confirmed at 246x~302x concentration ratio for a cell developed in FY 2012 under AM1.5D spectrum by Fraunhofer ISE. We continued to further improve the performance of concentrator cells in order to achieve an efficiency of 45%. Because spectral response in the cells showed that current was limited in the top cell, we tried to optimize anti-reflection coatings of the cells in order to increase quantum efficiency (QE) of the top cell. We succeeded in improving QE in the short wavelength region lower than 450nm, which contributed approximately 1.4% current increase under AM1.5D spectrum for the previous concentrator cells. We asked AIST to measure concentrator characteristics of an improved cell in January, and are waiting for results. We started a development of four junction cells focusing on the wafer bonding approach for inverted triple junction structure and InGaAs(0.75eV) cell structure grown on InP substrates. This year we investigated elementary technologies such as growth of a tunnel structure on inverted triple junction cells, smoothing of bonding surface, and so on. We continued a field test of concentrator module with inverted triple junction cells in Arizona USA and corrected data. No obvious degradation was observed after nine month exposure judging by current-voltage characteristics before and after the test. In a 10kW system with conventional triple junction cells, electricity production as almost same as initially expected was obtained, which was 1.1 times larger than that of a thin film Si module. We started field test of a 10kW system at University of Miyazaki this March to investigate a possibility of domestic installation from electricity production data which will be obtained in FY2014. We estimated module efficiencies by a solar simulator introduced this year. We obtained an efficiency of 33.1% for a current module with conventional triple junction cells. In FY2014 we are planning to obtain the target value of 35% for modules by using inverted triple junction cells, optimizing cell size, improving primary lens, and so on.
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