Modular Plants (MPs), designed for rapid deployment and adaptability, offer faster time-to-market. Their energy-efficient operation can significantly lower the carbon footprint of industrial processes. This work presents an Energy Management System (EnMS) Plug-&-Monitor architecture that enables rapid EnMS deployment and immediate insights into MP performance and energy consumption. An Asset Administration Shell ensures energy transparency through Energy Key Performance Indicators (eKPIs), aggregated across modules. It facilitates the structured and standardized representation and exchange of energy data in cooperation with the Process Orchestration Layer. Proposed submodels, including eKPI, energy baseline, and energy data exchange, provide valuable datasets for the Digital Product Passport.