Multi-criteria framework for rainwater-to-hydrogen systems in tropical residential energy transitions

• A multi-criteria framework is developed for rainwater-to-hydrogen systems. • Framework integrates technical, economic, environmental, and social dimensions. • Case study shows 151–219 kg H₂ per year with LCOH of 4.84–11.63 US$/kg. • CO₂ savings of 1.47–2.85 tonnes annually are achievable at household scale. • Rainwater-to-hydrogen complements PV, industrial H₂, and TENGs in transitions. Decarbonising residential energy in tropical regions requires solutions that integrate renewable generation, storage, and resource circularity. This study proposes and applies a multi-criteria framework to evaluate the feasibility of rainwater-to-hydrogen systems as a novel form of green hydrogen tailored for tropical households. The framework connects system inputs, including rainfall, rooftop area, photovoltaic capacity, and technical parameters, to performance indicators using five modelling equations. These indicators comprise hydrogen yield, solar-to-hydrogen (STH) efficiency, levelised cost of hydrogen (LCOH), avoided CO₂ emissions, and water circularity. They are assessed across technical, economic, environmental, and institutional-social dimensions, consistent with Ecological Modernisation Theory (EMT). A Malaysian case study demonstrates that rainwater-to-hydrogen systems can produce between 151 and 219 kilograms of hydrogen per household annually, with STH efficiency ranging from 9.9 to 14.4 percent. The LCOH is estimated at 4.84 to 11.63 US dollars per kilogram, while avoided emissions reach 1.47 to 2.85 tonnes of CO₂ per year. Comparative benchmarking further shows the distinctive positioning of rainwater-to-hydrogen: unlike industrial hydrogen, triboelectric nanogenerators (TENGs), or standalone solar PV, it uniquely combines renewable generation, long-duration storage, and water circularity. The novelty of this study lies in two contributions: (i) the development of a methodological framework that integrates technical, economic, environmental, and institutional dimensions into a unified evaluation model, and (ii) its application to the underexplored case of rainwater-to-hydrogen systems in tropical residential contexts, positioning them as a unique testbed for decentralised hydrogen adoption.