Solid oxide electrolysis: Techno-Economic assessment and impact of modularity under intermittent operation

Green hydrogen is a key enabler of climate neutrality. Among its production pathways, Solid Oxide Electrolysis (SOE) offers greater efficiency advantages, though less mature than low temperature electrolysis technologies. Renewable intermittency and limited SOE flexibility underscore the importance of studying SOE modularity for performance and cost evaluation. Thus, this techno-economic analysis of SOE systems brings novelty with the consideration of modularity with renewable input. To carry out the study, a multi-module SOE process model is developed and experimentally validated at stack level. For a reference system of 15 MW electrolysis power, LCOH ranges from 2.5 to 5.3 €/kgH 2 for electricity costs of 25–100 €/MWh, 60% capacity factor and steam integration, highlighting potential competitiveness compared to low temperature electrolysis. The trade-off between electrolyser operational flexibility and scale is assessed to identify optimal module sizes of 1.75 MW and 2.5 MW considering wind-only or PV/wind scenarios, underlining the need to adapt electrolyser design to energy availability. • A techno-economic modular SOE model was developed to assess intermittent operation and calculate LCOH. • Scenario analysis indicates LCOH at 3.0–6.5 €/kg for electricity prices between 25 and 100 €/MWh. • LCOH improves to 2.5–5.3 €/kg with steam integration. • Optimal module sizes of 1.75 MW and 2.5 MW are obtained for wind and hybrid PV/wind profiles. • The model can support sizing studies, configuration optimization, and comparative scenario analyses for modularSOE systems.