NOVELTY - A fuel cell system comprises fuel cell modules that contain sealed planar fuel cell stack, where the stack includes internal channels for delivery of fuel and air to fuel cells within the stack and removal of tail gas and spent air away from fuel cells within the stack, each of the fuel cell stack is mounted on a stack footprint area of a top member of a base manifold (10). The base manifold includes: at least two air openings (14, 15, 16, 17) outside of the stack footprint area; at least two spent air openings; at least two fuel openings; and at least two tail gas openings.    USE - As a fuel cell system (claimed), for producing power output.    ADVANTAGE - The system allows for a number of fuel cell stack modules to be connected together to provide a fuel cell system capable of producing power outputs that otherwise would have required large surface area cells or a stack with a large numbers of cells. The fuel cell system provides economies of scale by using small stacks mass-produced for the auxiliary power unit (APU) market to be used in place of large power output stack by mounting the stacks onto a modular base manifold.    DETAILED DESCRIPTION - A fuel cell system comprises fuel cell modules that contain sealed planar fuel cell stack, where the stack includes internal channels for delivery of fuel and air to fuel cells within the stack and removal of tail gas and spent air away from fuel cells within the stack, each of the fuel cell stack is mounted on a stack footprint area of a top member of a base manifold (10). The base manifold includes: at least two air openings (14, 15, 16, 17) outside of the stack footprint area that are in fluid communication with each other and with at least one opening inside of the stack footprint area that is in fluid communication with the stack internal channels for delivering air to the fuel cells within the stack; at least two spent air openings outside of the stack footprint area that are in fluid communication with each other and with at least one opening inside of the stack footprint area that is in fluid communication with the stack internal channels for receiving spent air from the fuel cells within the stack; at least two fuel openings outside of the stack footprint area that are in fluid communication with each other and with at least one opening inside of the stack footprint that is in fluid communication with the stack internal channels for delivering fuel to the fuel cells within the stack; and at least two tail gas openings outside of the stack footprint area that are in fluid communication with each other and with at least one opening inside of the stack footprint area that is in fluid communication with the stack internal channels for receiving tail gas from the fuel cells within the stack. The system includes at least two fuel cell modules that are juxtaposed with one another such that at least one air opening, spent air opening, fuel opening, and tail gas opening outside of the stack footprint area on the base manifold of one of the juxtaposed fuel cell modules is respectively juxtaposed with and connected in fluid communication with the air opening, spent air opening, fuel opening, and tail gas opening outside of the stack footprint area on the base manifold of an adjacent juxtaposed fuel cell module. The air opening is in fluid communication with an air source, at least one of the spent air openings is in fluid communication with the atmosphere or an air exhaust, at least one of the side fuel openings is in fluid communication with a fuel source, and at least one of the side tail gas openings is in fluid communication with the atmosphere or a tail gas exhaust. The fuel cell stacks comprise solid oxide fuel cells.    DESCRIPTION OF DRAWING(S) - The figure shows perspective view of a base manifold that can be used in fuel cell system.    Base manifold (10)    Fuel cell frame footprint (12)    Air openings (14, 15, 16, 17)    Top member openings (19)    Base manifold side member (23)