A reversible SOFC-based system for generating electricity, including: an solid-oxide-fuel-cell (SOFC) stack containing at least one elementary solid-oxide electrochemical cell, each of which is formed from a cathode, an anode and an electrolyte intermediate between the cathode and the anode; a separator of liquid and gas phases, which separator is connected to the outlet of the fuel-cell stack; a methanation reactor suitable for implementing a methanation reaction, the inlet of which is connected to the outlet of the phase separator and the outlet of which is connected to the inlet of the fuel-cell stack so that the mixture issued from the methanation reactor is introduced into the fuel-cell stack; and a tank for reversibly storing hydrogen, suitable for storing hydrogen, the outlet of which is connected to the inlet of the methanation reactor.