Techno-Economic and Environmental Assessment of Residential Photovoltaic Systems for Sustainable Urban Energy Transition and Climate Mitigation in Pakistan

Rising electricity prices, grid instability, and climate concerns are increasing the need for sustainable residential energy solutions in developing countries. This study evaluates four residential photovoltaic (PV) configurations for a household in Karachi, Pakistan, to identify a suitable option for sustainable urban energy transition and climate mitigation. The assessed systems include daytime PV with grid supply, daytime PV with 6 h battery backup and grid supply, daytime PV with full battery backup, and daytime PV with net metering. Energy requirements, installed capacity, area demand, and battery storage were calculated using household load data, while economic performance was assessed through payback period, net present value ( NPV ), and levelized cost of electricity ( LCOE ). Environmental benefits were evaluated using avoided CO 2 , CH 4 , and N 2 O emissions, and the best-performing system was further simulated in PVsyst. Case C, comprising daytime PV with full battery backup, achieved the highest NPV of USD 25,104.3 and a payback period of approximately 4 years. Case B achieved the second-highest NPV of USD 19,183.58 while providing a more practical balance between battery backup and grid support. Case D achieved the lowest LCOE of USD 0.0307/kWh. Fully solar-dependent configurations provided the greatest emission reductions. The findings support residential PV deployment as a practical pathway for improving urban energy security and reducing climate impacts.