Design and Development of Solar-Supported Electric Three-Wheeler Compatible to Bangladesh Perspectives

The rapid proliferation of battery-driven electric three-wheelers in Bangladesh has substantially increased demand for grid electricity allocated to battery charging, imposing additional strain on the national power grid. While these vehicles offer affordable, low-emission local transportation, their dependence on grid charging remains a growing concern for the country’s energy sector. This paper presents the design, energy-balance analysis, and MATLAB/Simulink simulation of a solar-assisted electric three-wheeler employing a rooftop photovoltaic (PV) panel to supplement battery charging and reduce reliance on conventional grid electricity. The proposed configuration comprises a 48 V, 100 Ah lead-acid battery pack, an 800 W differential motor, a 400 W rooftop PV panel, and a 20 A MPPT charge controller. This constitutes a design-stage, simulation-based study rather than a field-validated evaluation: all runtime, range, and energy figures are theoretical or simulation outputs, cross-checked against a limited, non-randomly sampled set of driver interviews and short spot measurements on comparable in-service vehicles pending prototype construction and instrumented field testing. Simulation results indicate the PV panel can supply 1.0–1.5 kWh/day depending on seasonal irradiance (annual-average: 1.08 kWh/day; best-case, single clear day: 1.5 kWh/day), with the annual-average yield offsetting approximately 25% of simulated annual traction-energy demand (defined as the useful PV energy delivered to the motor as a fraction of annual traction-energy demand, as distinct from gross PV generation). This is expected to reduce battery discharge depth/rate and extend estimated operating time, though these benefits and battery-life effects remain hypotheses pending experimental verification. An indicative techno-economic assessment—incorporating sensitivity analysis on solar yield, tariff, and system cost—suggests payback within roughly 6.5–22 months across explicit optimistic/central/pessimistic scenarios (central estimate ~10 months), with wide uncertainty. The study also provides an order-of-magnitude estimate of potential grid-electricity displacement at scale, excluding onboard battery energy, presenting national vehicle population as an uncertainty range. Results support rooftop solar as a plausible complementary energy source—not replacement—to grid charging, subject to prototype validation.