The Power-to-Ammonia (PtA) value chain is an important enabler of sector coupling and integration of renewable energy in the process industry. The PtA pathway typically uses 90-96 % of the incoming fluctuating energy to produce green hydrogen using electrolyzer systems [Rouwenhorst, 2019]. Hence to optimize the energy efficiency, flexibility, adaptability to fluctuating energy and cost of the PtA process, the correct choice of electrolysis technology is important. Each electrolysis technology has certain advantages and disadvantages in handling a fluctuating energy input [Lange, 2023]. The use of modular and heterogenous electrolysis systems, consisting of different types and sizes of electrolyzers, can utilize these advantages while counteracting the disadvantages. The project eModule researches a possible transfer of modular plant concepts, defined in the VDI/VDE/NAMUR 2776 standard for the process industry, to enable a fast, efficient, and flexible scale-up of electrolyzer systems. For that purpose, this paper evaluates different modular electrolyzer configurations in a flexible PtA value chain. A monolithic electrolyzer configuration, consisting of electrolyzers of same size and technology, is simulated and used as a benchmark. Different heterogenous plant configurations and corresponding process control strategies for energy integration are created and simulated in MATLAB/Simulink. Metrics for energy efficiency, flexibility, and adaptability to fluctuating energy input are defined and compared. It is shown that the use of modular heterogenous electrolyzer systems enable a more efficient green hydrogen and ammonia production, while making the system more flexible and adaptable to a fluctuating energy input. The advantages of using modular heterogenous electrolyzer configurations in the PtA value chain are quantified, and upcoming techno-economic evaluations can show the economic potential of such plants.