Abstract: The invention relates to a power generation system comprising:—at least one renewable energy source (5),—a reversible fuel cell module (9) exhibiting a electrolysis functioning mode where the fuel cell module (9) is powered by the renewable energy source (5) for generation of a combustible gas and a fuel cell functioning mode where the fuel cell module (9) generates electricity from a combustible gas,—a high temperature heat storage (19) coupled to said reversible fuel cell module (9) for maintaining the reversible fuel cell module (9) in a operation temperature range in the electrolysis functioning mode,—a combustible gas storage (17) coupled to the reversible fuel cell module (9) for storing the combustible gas generated by the reversible fuel cell module (9) in the electrolysis functioning mode and for supplying the combustible gas to the reversible fuel cell module (9) in the fuel cell function mode, where the reversible fuel cell module (9) is encapsulated by the high temperature heat storage (19).