Techno-economic analysis of grid-connected PV and second-life battery systems for net-zero energy houses

Net-zero energy houses (ZEHs) rely on energy-efficient building design and the incorporation of distributed generation and battery energy storage units. Nevertheless, two primary concerns arise: high investment cost of these units and harmful environmental impact of batteries. Using second-life batteries can overcome these concerns by reducing the cost of photovoltaic (PV)- battery systems and mitigating the adverse environmental effects of battery supply chain. Therefore, this study examines the techno-economic feasibility of utilizing second-life batteries for PV storage in grid-connected ZEHs in two provinces (Antalya and Istanbul) of Türkiye. First, two ZEHs with air-to-water heat pumps are designed using BEopt software. Next, the optimal PVbattery capacity in the ZEHs is determined using HOMER Grid software. Finally, the economic feasibility of using three types of batteries (new lead acid, new Li-ion, second-life Li-ion) in ZEHs is compared. The optimal design for a typical ZEH comprises a 5.92 kW PV and an 8.96 kWh second-life Li-ion battery in Istanbul (northern Türkiye), yielding an NPV of $10,906, and a 7.54 kW PV and an 11.52 kWh second-life Li-ion battery in Antalya (southern Türkiye), yielding an NPV of $16,402. The results indicate that using second-life Li-ion increases the NPV of PV-battery systems by 15 % in Istanbul and by 21 % in Antalya. The feasible system configuration categories for Türkiye’s economic and climatic conditions are ranked as: PV-second-life Li-ion > PV-no battery ? PV-new Li-ion > PV-new lead acid. Incentivizing the use of second-life batteries due to their environmental contribution could result in an even higher NPV increase.