This deliverable defines the EU-DREAM Data Platform as a modular, secure, and interoperable system built to support trusted data sharing in line with European data space principles. It begins by outlining requirements for data collection, storage, integration, monitoring, access, visualization, security, and deployment, ensuring privacy and sovereignty while maintaining usability. The architecture translates these requirements into layered components using open-source technologies, enabling multi-source data acquisition, standardized formats, reliable access, and strong security. Key features include connectors, federated identity, usage policies, catalogues, open interfaces, secure communication, auditability, and distributed infrastructure, positioning the platform as a foundation for transparent, governed, and user-centric energy data management.