Climate change exerts substantial adverse effects on water resources within the catchment area of Lake Velence in Hungary, intensifying conflicts among stakeholders and diverse water users. This region, characterized by rapid urbanization and economic expansion, also exhibits ecological heterogeneity, including significant wetland areas, some designated as Ramsar sites. At the same time, population growth and modern real estate development have led to a high density of solar panel installations, resulting in above-average per-property renewable energy production capacity across the country. This study proposes an inter-basin water transfer system to mitigate the hydrological impacts of climate change, leveraging the area’s topography and solar energy production potential by integrating pumped hydro storage reservoirs and surplus solar energy to transfer water from the adjacent Váli-víz watershed is considered. The ecological flow requirements of the donor area are also considered to protect its ecosystem. The objective is to design a sustainable, low-carbon water replenishment system that addresses the region’s economic, social, and ecological requirements. By synchronizing excess solar energy production with pumped hydro storage systems, the approach ensures dual functionality: renewable energy storage and strategic water supply enhancement for Lake Velence, thus increasing the system and the area’s resilience under climate stress.