Towards sustainable urban transit: Design of a solar-powered metro rail system

This study evaluates the technical, economic, and environmental feasibility of integrating rooftop solar systems into Dhaka Metro Rail MRT Line-6 infrastructure. A total of 34,255 PV modules is proposed across 69,789 m² of rooftop area spanning 16 stations and 5 depot facilities, with a combined capacity of 20.38 MWp DC and 19.60 MW AC. PVsyst simulation results show an annual generation of 25,521 MWh, a performance ratio of 0.79, and specific production of 1252.76 kWh/kWp/year. The hybrid system, incorporating energy storage and grid interconnection, achieves a payback period of 6 years, a net present value of USD 20.05 million, and a return on investment of 234.1%. Environmental analysis reveals the system would avoid 2,35,297.3 tCO₂ emissions over 20 years. In parallel, HOMER Pro software was used to model optimized hybrid PV–grid–battery systems across three metro zones and these are Uttara North, Uttara Center, and Uttara South (Zone A), Agargaon, Kazipara, and Shewrapara (Zone B), and Bangladesh Secretariat and Motijheel (Zone C). Each system was simulated with 600–650 kW PV, 500 kW battery inverters, and lithium-based storage ranging from 800 to 1000 kWh. Zone C achieved the highest energy output of 1.63 GWh/year, with a Levelized Cost of electricity of $0.131/kWh and Net Present Cost of $1.88 million. Zones A and B yielded 1.49 and 1.47 GWh/year with LCOEs of $0.126 and $0.125/kWh, respectively. Emission reduction in Zone C reached 896 tons of CO₂ annually. These results validate the technical, economic, and ecological viability of deploying solar PV systems for urban metro infrastructure in developing nations like Bangladesh. Sensitivity analysis has also shown how resource variability affects the optimal system configuration and economics.