FUEL CELL SYSTEM ASSEMBLY

The invention relates to a fuel cell system assembly comprising at least two coupled fuel cell systems (A, B) that can be operated at different load points, each fuel cell system (A, B) being connected to a respective cooling circuit (A, B) comprising a circulating coolant, via a coolant supply line (A, B) and a coolant drain line (A, B). According to the invention, the cooling circuits (A, B) are coupled via a common return line (), via which the coolant supply lines (A, B) can be supplied with coolant, and a return conduit of at least one ancillary unit (), for example an electric heating device () and/or a heater core (), is connected to the common return line ().