Smart energy systems are meant as groups of energy conversion units that fulfill the requirements of several users according to "smart rules". This paper considers an existing energy system including various units fed by renewable sources which serve thermal and electric users in a mountain resort. The goal is to find smart rules to operate the system by identifying the best operating alternative among a complete set deriving from connection to or isolation from the electric grid, inclusion or exclusion of storage systems and/or by-pass in the heat recovery system of the CHP units. To this end, detailed design and off-design models of each alternative are first built using field data or data supplied by manufacturers. The operation of each alternative and the capacities of the thermal and electric storages are then optimized to obtain the maximum profit. Results show that both electric and thermal storage systems must be included when the system works in isolation from the grid, but the profit is negative. Conversely, when the system is connected to the grid, the best operation strategy is achieved by including a thermal storage, while the inclusion of the electric storage is disadvantageous. (C) 2018 Elsevier Ltd. All rights reserved.