Distributed energy entities such as energy communities (ECs), Virtual Power Plants (VPPs) and distributed generation (DG) are the new ingredients of the energy transition, which aims to more sustainable energy systems. However, the power grids should be able to accommodate these new entities remaining reliable and secure, otherwise, the energy transition would fail. In particular, with the increasing diffusion of Non-Programmable Renewable Sources (NPRS), the volatility in energy production increased, as well as the dispatching costs incurred by the Transmission System Operators (TSO): the latter are then reflected in the end-users' bills. The thesis discusses the possible effective imbalances within a fictitious energy community: these imbalances born from the difference between the real-time (RT) exchange with the grid and the forecasted (FO) one, being the latter the programmes post balancing market (BM).