Abstract Green hydrogen is increasingly cited as a solution to the decarbonisation of industry. Its large-scale production is still a recent topic with uncertainties. In this paper, an economic impact assessment (EIA) method is explained. A modular and flexible cost model is generated, which estimates the LCOE (Levelized Cost of Energy) of an offshore wind farm and the LCOH (Levelized Cost of Hydrogen) of a hydrogen generation plant either as a hybrid renewable energy system (HRES) or independent from each other. The costs are estimated using a schedule-based approach, which considers the reliability, maintenance operations as well as production of both the offshore wind farm and the hydrogen generation plant. Developed EIA is demonstrated for Belgium using Mermaid Offshore Wind Farm.