Abstract: The invention relates to a decision support system (DSS, 1) for maintenance of renewable energy generators, such as wind turbine generator (WTG, 11). A forecasting module (FM, 21) outputs renewable power plant relevant parameters (PF) in a prediction window of time (TW), whereas an optimization module (OPT, 22) receives the relevant parameters (PF), and proposes a maintenance schedule (PROP-MAN) for the renewable power plant (WPP) in order to optimize the produced energy with respect to the demand in said predefined prediction window (TW). A renewable energy generator condition module (WT-CON, 23) outputs condition data into maintenance recommendations (REC-MAN) for one or more renewable energy generators. Finally, a renewable energy generator maintenance recommendation module (WTM, 24) is arranged to combine the proposed maintenance schedule and the maintenance recommendations into a final maintenance decision proposal (FIN-PROP-MAN).