Polymer-Electrolyte-Membrane (PEM) fuel cell systems will contribute to enable climate-neutral mobility through the chemical reaction of hydrogen and oxygen. PEM fuel cells address applications which are hardly decarbonized by HV batteries. But apart from its advantages, such as short refueling times and higher energy densities related to batteries or locally emission-free operation compared to conventional drivetrains, the fuel cell technology still faces challenges that inhibit its wide market penetration. Especially the low production volumes result in costly manufacturing processes. The assembly of the fuel cell stack and balance-of-plant components to a system is predominantly of manufactory character. There is a consensus in the literature that scaling up the production is associated with cost reduction effects. But in order to increase the demand that justifies a growth in unit numbers, the costs per system have to be reduced. With regard to this so-called "hen-and-egg problem", a reduction of production costs for small output numbers is necessary, while already considering the future necessity to scale the production. This paper discusses the development of scalable production concepts for PEM fuel cell system assemblies. In addition to a modular production concept, the associated production scenarios are also considered. For a generic fuel cell system, a possible assembly sequence and assembly tasks are derived from the bill of materials. The assembly durations for the individual steps are then determined according to the Methods-Time-Measurement (MTM) methodology. This methodological approach is intended to provide an estimate for each process step in the assembly and can be transferred to other fuel cell systems. The paper shows how a bill of materials can be used to estimate the cycle time for a system, but also the cycle time for defined stations. In addition, by considering different scaling mechanisms, further improvements in the assembly process are shown, based on the results from the MTM analysis
