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Reversible solid oxide cell (rSOC) can flexibly switch between the electrolysis mode and the fuel cell mode for electrical energy storage and power generation. For practical application, sweeping gas is needed to bring in the reactants and take out the products timely. In this study, we use steam as anode sweeping gas in electrolysis to decrease the overpotential loss and collect pure O 2 , which is then used as the fuel cell cathode oxidant. The real fluctuating power generated from solar photovoltaic is used as the power supply, which allows rSOC to generate H 2 from 6:45 a.m. to 5:45 p.m. and produce electricity in the night. Compared with the conventional strategy, the proposed system can utilize more than 35% electricity in electrolysis, and its efficiency and total H 2 production can be increased by 8% and 50%, respectively. The total power generation and the power density are also increased by 290% and 160%, respectively. Overall, this new strategy results in a doubled round-trip voltage efficiency due to the much-decreased overpotential losses in the electrochemical processes. This study provides a guidance for the optimization of practical rSOC application with dynamic operating conditions. • 2D dynamic models for tubular SOEC and SOFC are developed. • Parametric studies on SOECs are conducted with fluctuating PV power supply. • H 2 O is used as sweeping gas in SOEC and pure O 2 is used as reactant in SOFC. • The production efficiency and rate of H 2 are increased by 8% and 50%, respectively. • Power generation and power density are increased by 2.9 and 1.6 times, respectively. [ABSTRACT FROM AUTHOR]