FuelCell Energy, Inc. (FCE) and its subsidiary, Versa Power Systems, will design, fabricate, and test a state-of-the-art 400 kilowatt (kW) prototype system comprised of two thermally self-sustaining atmospheric-pressure 200 kW Solid Oxide Fuel Cell (SOFC) power generators to be installed and operated at a prominent site. This work will demonstrate SOFC stack reliability and endurance and utilize FCE’s SOFC system design philosophy based on factory-assembled stack building blocks, which may be used to fabricate larger multi-stack modules for both sub-megawatt (MW) and multi-MW systems applications. Ultimately, thirty-two baseline 120-cell SOFC stack blocks will be fabricated and integrated into four 100 kW modular power blocks (MPBs) for the 400 kW prototype system. The system design will include novel balance of plant (BOP) components and operational/control strategies to improve SOFC stack endurance and reliability. The system testing will serve to validate key design features of the MPB (e.g., SOFC stack arrays and towers, and integration of hot BOP components), which are enabling technologies for larger-scale MW-class stack modules.