Hydrogen production as a flexible energy carrier is expected to play a promising role in supporting recover curtailed grid-tied renewable energy. The aims of this research focus on the potential quantification and sensitivity assessment of power to hydrogen, based on the history of electricity load and generation in Kyushu. First, a simulation model was developed considering detailed technical constraints. Results indicated that increasing grid-tied renewable production raised the increasing flexibility requirement and LACE of mixed renewable energy, curtailment presented variations across months, and the optimal combination of solar and wind generation could decrease curtailment. Then the technical-economic performance of renewable energy to hydrogen production was estimated under different scenarios and assumptions. The capacity and full-load operating period were quantified based on the sorted surplus renewable descending curves. Potential and investment scenarios of the proposed P2G approach highly depended on the structure of the combined solar and wind resources, converting efficiency and H-2 price. Gross renewable production was fixed to an annual grid load ratio of 40%. Implementation of optimal large-scale electrolyzer raises the effective utilisation ratio of renewable production from 59.1% to 74.3%. 57.5% of the surplus renewable generation was converted into hydrogen to decarbonize the social energy supply system. (C) 2019 Elsevier Ltd. All rights reserved.