Abstract: Large-scale renewable power-to-hydrogen （ReP2H） systems enable efficient utilization of wind and solar resources while supplying green hydrogen to downstream industries, thereby decarbonizing chemical and transportation sectors. To reduce equipment and land-use costs, some projects adopt N-in-1 configurations, where multiple stacks share a common balance-of-plant （BoP） system. However, due to the coupling of gas–liquid circulation processes, the startup and shutdown of individual stacks become interdependent, leading to reduced operational flexibility compared with conventional one-in-one configurations. To address the challenges of N-in-1 electrolyzers under the variability and uncertainty of renewable generation, this paper proposes a scheduling method for multiple 4-in-1 electrolyzers based on information gap decision theory （IGDT）. First, the power consumption, hydrogen production, and on-off switching of the stacks are explicitly modeled. Second, the inter-stack couplings are characterized according to the operational logic of practical 4-in-1 systems. Finally, renewable uncertainty is handled using a robust IGDT framework, and the resulting scheduling problem is formulated as a mixed-integer second-order cone programming （MISOCP） model. Case studies demonstrate that the proposed method increases revenue by up to 2.3% while effectively handling renewable uncertainty. With a revenue deviation factor of 0.15, the system can tolerate forecast errors of up to 20%, indicating strong robustness. Furthermore, the performance differences between N-in-1 and one-in-one configurations in accommodating renewable energy are quantitatively analyzed.