Hybrid PV/T and ground source heat pump systems for low-exergy heating in residential buildings: A techno-economic and environmental evaluation

Abstract

Growing energy demand and fossil fuel dependency in Iran's residential sector have intensified challenges related to gas supply shortages and electricity imbalances. Addressing these issues requires innovative, low-carbon heating solutions. This study evaluates the techno-economic and environmental performance of a low-exergy hybrid heating system integrating photovoltaic/thermal collectors with a ground-source heat pump across six Iranian climate zones. Using Polysun® simulations, system behavior was analyzed on annual, monthly, and hourly scales. Results show that annual thermal energy outputs reached 120,767kWh in Ardabil and 118,876 kWh in Kerman, with corresponding seasonal performance factors of 3.0 and 2.9, indicating efficient utilization of low-temperature renewable heat. The PV subsystem produced up to 36,745 kWh/a in Kerman, while annual CO2 savings was 58,370 kg. Economically, Kerman achieved the best performance, with a life cycle cost of $197,708, a net present value of $237,989, and investment recovery in year 17. The findings confirm that the proposed low-exergy system is technically feasible and economically promising, especially in sunny, semi-arid regions. The deployment of such systems can mitigate fossil fuel reliance, enhance grid stability, and reduce emissions. Redirecting national energy subsidies toward such clean and efficient systems could accelerate their adoption and support Iran's transition toward a resilient, low-carbon energy future. © 2025 The Authors