Abstract
Digital Twins (DTs) are pivotal in enabling real-time monitoring and optimization across diverse domains, but their deployment is often constrained within isolated silos—hindering seamless interoperability, data governance, and cross-domain collaboration. In this paper, we propose a novel architecture for Federated Digital Twins (FDTs) that integrates knowledge graph-based DTs with standardized Data Space technologies to overcome these barriers. Building upon our previous work on SINDIT, we extend its capabilities by incorporating Data Space protocols based on the International Data Spaces (IDS) Reference Architecture, enabling secure, sovereign, and semantically interoperable data sharing. We illustrate the approach through a real-world use case in the photovoltaic (PV) panel lifecycle, where stakeholders collaboratively manage and share data—such as material composition, operational history, and recycling records—via interconnected DTs and Data Spaces. This highlights the potential of FDT ecosystems to support secure data exchange and circularity across industrial value chains.