Optimizing energy efficiency in residential buildings: A comprehensive evaluation of solar concrete water heaters integrated with photovoltaics and thermoelectric cooling

This study presents a Solar Concrete Water Heater (SCWH) integrating solar water heating, photovoltaic (PV) power generation, and thermoelectric generator (TEG) cooling, functioning as a structural roof component. The system was tested in three stages: Phase One evaluated Copper (C)- and Galvanized Iron (GI)-SCWHs, Phase Two integrated PV panels, and Phase Three added TEGs for cooling and additional power generation. Experiments at flow rates of 0.12, 0.24, and 0.36 L/min revealed average thermal efficiencies of 24.75% for C-SCWH and 24.20% for GI-SCWH, with respective exergy efficiencies of 19.28% and 18.38%. PV panels generated 797.4 Wh of electricity at 12% efficiency, while TEGs produced 171.25 Wh at 11% efficiency. The system heated 108 liters of water to 50°C in five hours and reduced indoor temperatures by up to 6.2°C. Overall system efficiency reached 46.4%, supported by robust Heat Utilization Factor (HUF) and Coefficient of Performance (COP) metrics. Economic analysis showed annualized savings of 161.58 USD and lifetime savings of 55,113.57 USD. Lifetime carbon reductions totalled 180,704.32 kg for C-SCWH and 206,921.09 kg for GI-SCWH, corresponding to carbon credit earnings of 4,165.37 USD and 4,194.12 USD. This roof design offers a sustainable solution to residential energy demands, reducing dependence on conventional sources.