Stack assembly comprising flexible compression force mat

A solid oxide fuel or electrolysis cell stack assembly for connection to a solid oxide fuel or electrolysis cell system, said assembly comprising

• at least one solid oxide fuel or electrolysis cell stack, the at least one stack comprises a plurality of fuel cells or electrolysis cells, the at least one stack comprises a top face, a bottom face, a plurality of side faces, fuel gas inlet, fuel gas outlet, oxidant gas inlet and oxidant gas outlet,
• a rigid housing with one closed top end, one open bottom interface end opposite the closed end and a plurality of sides, the housing enclosing the at least one stack top face and the plurality of side faces, the open bottom interface end is adapted to be connected to an interface counterpart of said solid oxide fuel or electrolysis cell system and provides interface for fuel gas and oxidant gas between the at least one stack and said system,
• a plurality of flexible compression force mats positioned inside the housing, at least one of said flexible compression force mats positioned between the at least one stack top face and the closed top end of the housing and at least one of said flexible compression force mats positioned adjacent a stack side face, the compression force mats providing compression force for the at least one stack,
• flexible fixation mats positioned inside the housing and respectively abutting two opposing stack side faces and corresponding sides of the housing to fix the at least one stack in the housing, and
• a flexible-interface-fixture positioned adjacent to the open bottom interface end of the housing that at least partly encloses the at least one stack within the housing and at least partly covers the bottom face of the at least one stack, the flexible-interface-fixture having a thickness in the range of 0.1-3 mm and a flexural stiffness of between 0.1 Nm and 1000 Nm.