Solid oxide fuel cell assemblies comprise packets of multi-cell-sheet devices based on compliant solid oxide electrolyte sheets that form a fuel chamber and support anodes interiorly and cathodes exteriorly of the chamber that can be electrically interconnected to provide a compact, high voltage power-generating unit; added frames can support the oxide sheets and incorporate fuel supply and air supply conduits or manifolds permitting stacking of the assemblies into fuel cell stacks of any required size and power-generating capacity.