The global and local environments are experiencing profound transformations in the 21st century, primarily due to the adverse impacts of climate change. Increasing temperatures and shifts in precipitation patterns present challenges to the natural world and human-made structures. Countries and settlements strive to reduce carbon dioxide emissions through the broader use of renewable energy sources. Adaptation to changing conditions is highly emphasized. These circumstances can be improved by more efficient and multipurpose uses of existing infrastructures or with small-scale expansions and broader, more complex use of renewable resources. A small settlement at Lake Velence, Nadap, has the highest ratio of solar panels in Hungary. It can be achieved by combining this advantage with its hilly location, sustainable energy security, and economic benefits. This paper develops a theoretical methodology for how rainwater and gravity energy storage can be utilized using the geographical characteristics of the settlement and its existing solar panel capacities. The methodology uses rainwater budget modeling, local solar-cell capacity calculation, and the selection of state-of-the-art mechanical gravity energy storage systems based on a literature review. Additionally, this paper aims to develop a rainwater management system that optimizes crop irrigation and maximizes energy storage in hilly settlements, with the cooperation of stakeholders, in a multidisciplinary approach.