This deliverable summarizes the work completed in Task 1.2, “Overall System Architecture Design,” which defines the Reference Architecture for the EU-DREAM platform. Developed in line with ISO/IEC/IEEE 42010:2022 and the 4+1 View Model, it provides a modular, scalable framework integrating components such as Digital Twin Orchestrators, AI-based optimization, NLP interfaces, and secure, interoperable data services using technologies like Docker, Kubernetes, Apache Kafka, and MongoDB. The architecture supports diverse stakeholders—prosumers, DSOs, energy communities, and vulnerable users—through role-based access, real-time monitoring, and compliance with EU regulations, ensuring replicability, user-centric design, and alignment with EU-DREAM’s goal of democratizing digital energy participation across Europe.