A dual-resource rooftop system for water-energy sustainability: a case study at Near East University’s grand library

The present paper introduces a novel rooftop hybrid system that integrates a solar power system (SPS) and a rainwater harvesting system (RHS) at the Grand Library of Near East University in Northern Cyprus. In this study, ground-based rainfall measurements from 2015 to 2023 were compared with six satellite-derived precipitation datasets (CHIRPS, CFSR, ERA5, ERA5-AG, ERA5-LAND, and MERRA2) to determine the potential for rainwater collection. The results demonstrate that the ERA5-AG dataset produced the highest accuracy based on the values of key metrics (R-squared, Root Mean Squared Error, and Mean Absolute Error), and was used to estimate rainfall harvesting potential. Based on maximum and average daily rainfall, the winter season provided the most potential, with up to 1,665.12 m³ and 373.51 m³ of collected rainwater, respectively. Moreover, the environmental and economic viability of the proposed RHS-SPS system is evaluated through mathematical modelling. The results indicate that a tilt angle of 34° and a north-oriented face generated the highest annual energy output (735,316.3 kWh) and the best capacity factor (19.52%) among the various orientation angles. Furthermore, the Levelized Cost of Energy (LCOE) for the system varied from 2.860 to 5.503 cents/kWh. Besides, a 34° tilt produced the most reduction in CO2, according to analysis of the environmental assessment. According to the findings, the RHS-SPS system aims to address two critical challenges in semi-arid regions (renewable energy production and water conservation) and achieve the Sustainable Development Goals.