A method for managing a hybrid renewable energy/generator set system, said hybrid system including a renewable energy production means and a plurality of generator sets, said system being connected to an electricity grid with intermittent availability, the system being managed as a function of a reserve power denoted as P res taking account of said intermittence, said method comprising: - a step of determining a reserve power including: ▪ a sub-step of determining a load reserve power denoted as P res load ▪ a sub-step of determining a renewable energy reserve power denoted as P res lRE; ▪ a sub-step of determining an electricity grid reserve power P res GRID; the reserve power P res is given by the following expression: P res = P res load + P res RE + P res GRID - a step of determining the states of the generator sets as a function of the reserve power P res previously determined; the method being characterised in that the electricity grid reserve power P res GRID is given by the following expression: P res GRID = − P prev GRID − P GRID t − 1 where P prev GRID is the predicted power of the electricity grid, P GRID ( t - 1) is the last known value of the power available from the electricity grid and that the predicted power of the electricity grid is given by the following expression: P prev GRID = GRID prev avail × P GRID t − 1 where P GRID( t - 1) is the last known value of the power from the electricity grid GRID prev avail is an availability prediction of the electricity grid, said availability being given by: GRID prev avail = { 0, P avail h < P avail thres GRID prev avail h, P avail h ≥ P avail thres where GRID prev avail h is an availability prediction of the electricity grid at the time horizon h, P avail ( h) is the probability granted to said prediction at the time horizon h and P avail thres is a probability threshold deemed acceptable. - a step of determining a reserve power including: ▪ a sub-step of determining a load reserve power denoted as P res load ▪ a sub-step of determining a renewable energy reserve power denoted as P res lRE; ▪ a sub-step of determining an electricity grid reserve power P res GRID; the reserve power P res is given by the following expression: P res = P res load + P res RE + P res GRID ▪ a sub-step of determining a load reserve power denoted as P res load ▪ a sub-step of determining a renewable energy reserve power denoted as P res lRE; ▪ a sub-step of determining an electricity grid reserve power P res GRID; - a step of determining the states of the generator sets as a function of the reserve power P res previously determined; the method being characterised in that the electricity grid reserve power P res GRID is given by the following expression: P res GRID = − P prev GRID − P GRID t − 1 where P prev GRID is the predicted power of the electricity grid, P GRID ( t - 1) is the last known value of the power available from the electricity grid and that the predicted power of the electricity grid is given by the following expression: P prev GRID = GRID prev avail × P GRID t − 1 where P GRID( t - 1) is the last known value of the power from the electricity grid GRID prev avail is an availability prediction of the electricity grid, said availability being given by: GRID prev avail = { 0, P avail h < P avail thres GRID prev avail h, P avail h ≥ P avail thres where GRID prev avail h is an availability prediction of the electricity grid at the time horizon h, P avail ( h) is the probability granted to said prediction at the time horizon h and P avail thres is a probability threshold deemed acceptable. where P prev GRID is the predicted power of the electricity grid, P GRID ( t - 1) is the last known value of the power available from the electricity grid and that the predicted power of the electricity grid is given by the following expression: P prev GRID = GRID prev avail × P GRID t − 1 where P GRID( t - 1) is the last known value of the power from the electricity grid GRID prev avail is an availability prediction of the electricity grid, said availability being given by: GRID prev avail = { 0, P avail h < P avail thres GRID prev avail h, P avail h ≥ P avail thres where GRID prev avail h is an availability prediction of the electricity grid at the time horizon h, P avail ( h) is the probability granted to said prediction at the time horizon h and P avail thres is a probability threshold deemed acceptable.