Techno-economic–environmental assessment of PV–second-life battery systems with PCM-assisted thermal management in low peak-load residential grids of Iran

This study evaluates the techno-economic and environmental feasibility of hybrid photovoltaic (PV)–second-life lithium-ion battery (SLB) systems equipped with passive phase-change-material (PCM) cooling for residential and agricultural consumers in low-peak-load regions. An hourly (8760-point) dynamic model was developed to simulate PV generation, battery charge–discharge behavior, and grid interaction under Iran’s real time-of-use tariff structure, while explicitly incorporating multi-mechanism battery degradation (cycle, calendar, high-SoC, and thermal aging). The framework was validated using empirical load and PV data from Gilan Province and subsequently extended to construct a national techno-economic atlas for all 31 provinces. Results show that integrating SLBs with rooftop PV can reduce peak-load demand by 5–50%, supply up to 250 MW of surplus electricity to the grid annually, and significantly improve household and agricultural cost savings. PCM cooling effectively stabilized cell temperature, limiting annual degradation to about 2% and extending battery lifetime by nearly 60% compared with conventional air cooling. Nationwide analysis revealed pronounced spatial heterogeneity, with northern and north-western provinces emerging as the most economically viable regions, achieving internal rates of return of approximately 25–26% under current tariff and climatic conditions. Overall, the PV–SLB–PCM system demonstrates strong technical performance, economic viability, and environmental benefits, offering a scalable pathway for sustainable electrification and carbon reduction in distributed energy systems.