Abstract: The present invention relates to a direct-coupled water electrolysis system and a method of configuring a such system comprising at least four components, a PV-array which is directly connected to one or more electrolyzer stacks, an electrolyzer system balance-of-plant, and an auxiliary power supply, the method comprising the steps of: a) providing a predetermined initial performance curve, providing an average degradation rate, and calculating an anticipated performance curve of the PV array; b) providing a predetermined initial performance curve, providing an average degradation rate, and calculating an anticipated performance curve of the electrolyzer stack(s); c) configuring the electrolyzer stack(s) by matching the anticipated electrolyzer stack(s) performance curve with the anticipated PV array performance curve.