Provided is a thermal energy storage plant including a charging circuit where a first working fluid is circulated, the charging circuit includes a first fluid transporting machine for generating a flow of the first working fluid in charging circuit, a heating device electrically powered for transferring heat to the first working fluid, a heat accumulator for storing the thermal energy of the first working fluid, the heat accumulator including a hot end for receiving the first working fluid at a first temperature and a cold end for letting the first working fluid exit the heat accumulator at a second temperature lower than the first temperature, the heat accumulator includes a plurality of heat storage units connected in series between the hot end and the cold end, which may be separated by valves.