A fuel cell stack array is disclosed. The fuel cell stack array includes a first fuel cell stack having a first upper frame structure formed with a first through-hole for exposing a first topmost connector layer positioned at top of a first single cell stack structure, a second fuel cell stack having a second upper frame structure formed with a second through-hole for exposing a second topmost connector layer positioned at top of a second single cell stack structure, and a first current collector electrically connecting the first and second topmost connector layers via the first and second through-holes.

A system for clamping a high-temperature SOEC/SOFC stack, including: an upper clamping plate and a lower clamping plate between which the stack can be clamped, each plate including at least one clamping orifice; at least one clamping rod configured to extend through clamping orifices in the upper and lower clamping plates to allow them to be assembled; a clamping mechanism level with each clamping orifice, configured to interact with the at least one clamping rod; and at least one electrically insulating plate configured to be located between the stack and at least one of the upper and lower clamping plates.

A system for clamping a high-temperature SOEC/SOFC stack, including: an upper clamping plate and a lower clamping plate between which the stack can be clamped, each plate including at least one clamping orifice; at least one clamping rod configured to extend through clamping orifices in the upper and lower clamping plates to allow them to be assembled; a clamping mechanism level with each clamping orifice, configured to interact with the at least one clamping rod; and at least one electrically insulating plate configured to be located between the stack and at least one of the upper and lower clamping plates.

A solid oxide type fuel battery cell includes a substrate that has electrical insulation, a solid electrolyte that includes first parts, and residual parts different in shape from the first parts, a plurality of electricity generation elements, each electricity generation element including a fuel electrode on the substrate, one of the residual parts on the fuel electrode, and an air electrode on the one of the residual parts, a length of each electricity generation element in a longitudinal direction being defined by a length of the air electrode, and a plurality of electrical connection parts, each electrical connection part being disposed between adjacent two of the plurality of electricity generation elements, each electrical connection part including an electrical connection member that electrically connects a fuel electrode of first one of the plurality of electricity generation elements and an air electrode of second one of the plurality of electricity generation elements.

A solid oxide type fuel battery cell includes a substrate that has electrical insulation, a solid electrolyte that includes first parts, and residual parts different in shape from the first parts, a plurality of electricity generation elements, each electricity generation element including a fuel electrode on the substrate, one of the residual parts on the fuel electrode, and an air electrode on the one of the residual parts, a length of each electricity generation element in a longitudinal direction being defined by a length of the air electrode, and a plurality of electrical connection parts, each electrical connection part being disposed between adjacent two of the plurality of electricity generation elements, each electrical connection part including an electrical connection member that electrically connects a fuel electrode of first one of the plurality of electricity generation elements and an air electrode of second one of the plurality of electricity generation elements.

A single fuel cell according to the present disclosure includes a power generation section, a power non-generation section which does not include the power generation section, and an oxygen-ion-insulating gas seal film arranged so as to cover the surface of the power non-generation section, and the gas seal film is configured by a structure formed by firing a material containing MTiO.sub.3 (M: alkaline earth metal element) and metal oxide. The structure may include a first structure and a second structure which are different in composition, the first structure may include components derived from MTiO.sub.3 in larger amounts than the second structure, the second structure may include a metal element contained in the metal oxide in a larger amount than the first structure, and the area ratio of the second structure in the structure may be not less than 1% and not more than 50%.

A single fuel cell according to the present disclosure includes a power generation section, a power non-generation section which does not include the power generation section, and an oxygen-ion-insulating gas seal film arranged so as to cover the surface of the power non-generation section, and the gas seal film is configured by a structure formed by firing a material containing MTiO.sub.3 (M: alkaline earth metal element) and metal oxide. The structure may include a first structure and a second structure which are different in composition, the first structure may include components derived from MTiO.sub.3 in larger amounts than the second structure, the second structure may include a metal element contained in the metal oxide in a larger amount than the first structure, and the area ratio of the second structure in the structure may be not less than 1% and not more than 50%.

A fuel cell module includes: a housing; a cell stack; a reformer; and an oxygen-containing gas supply section. The cell stack comprises fuel cells which are arranged along a predetermined arrangement direction, and is housed in the housing. The reformer is disposed above the cell stack in the housing. The oxygen-containing gas supply section is disposed along the predetermined arrangement direction of the fuel cells so as to face the cell stack and the reformer, and has a gas flow channel through which an oxygen-containing gas to be supplied to the fuel cell flows downwardly. Moreover, in the oxygen-containing gas supply section, the gas flow channel has a first region and a second region which is greater than the first region in flow channel width in a direction perpendicular to a direction in which an oxygen-containing gas flows, and the predetermined arrangement direction of the fuel cells.

A fuel cell module includes: a housing; a cell stack; a reformer; and an oxygen-containing gas supply section. The cell stack comprises fuel cells which are arranged along a predetermined arrangement direction, and is housed in the housing. The reformer is disposed above the cell stack in the housing. The oxygen-containing gas supply section is disposed along the predetermined arrangement direction of the fuel cells so as to face the cell stack and the reformer, and has a gas flow channel through which an oxygen-containing gas to be supplied to the fuel cell flows downwardly. Moreover, in the oxygen-containing gas supply section, the gas flow channel has a first region and a second region which is greater than the first region in flow channel width in a direction perpendicular to a direction in which an oxygen-containing gas flows, and the predetermined arrangement direction of the fuel cells.

A fuel cell system for enabling maintenance of a stack module without stopping operation thereof, and a method of replacing a stack module of the fuel cell system are provided. The fuel cell system includes a plurality of stack modules that are connected in parallel to a hydrogen line and an air line. Two or more of the stack modules are connected to form a group, and an inverter is connected to the group of the stack modules and is capable of being turned on and off.