The Life Cycle Cost (LCC) of energy systems including Renewable Energy Sources (RES) strongly depends on the Operation and Maintenance (O&M) costs. Nowadays, many components of these energy systems are equipped with Prognostics & Health Management (PHM) capabilities, for estimating their current and future health states. This information is intended to be used for the optimization of O&M. It is an ambitious and challenging objective as the uncertain information brought by PHM must be combined with other factors influencing O&M, such as the limited availability of maintenance crews, the variability of energy demand and production, the long-time horizons of energy systems. In this work, we formalize the O&M optimization of...