Hybridisation of renewable power plants with storage has become a central topic driven by the increasing midday price cannibalisation, declining investment costs of battery energy storage systems (BESSs), and growing technical curtailments resulting from higher renewable penetration. As a consequence, industry stakeholders now demand robust and validated operational solutions, including energy management systems (EMSs) for such power plants. These systems play a pivotal role in maximising revenues and extending the lifetime of critical assets such as BESSs. To address this need, this paper proposes a modular EMS architecture built upon industry-grade standards, enabling flexible adaptation to diverse hybrid plant configurations and evolving operational requirements from system operators or plant owners. The effectiveness of the proposed EMS is demonstrated through a case study of a PV–BESS hybrid power plant participating in the Spanish electricity markets.