Strategic Charging and Sizing of Electric Bus Batteries under Solar Availability

The increasing integration of renewable energy (RE) into power systems introduces variability and instability, necessitating effective energy storage solutions such as batteries. Electric buses, which rely on batteries, often face range limitation, prompting the use of larger battery capacities to ensure reliable operation. However, larger batteries increase upfront costs, raising concerns about economic feasibility. To address this issue, this study explores a strategy in which buses are pre-charged during daytime solar peaks to support evening and nighttime operations, thereby aligning energy consumption with RE availability. A cost-optimisation model is developed to evaluate the economic impact of different battery sizes and charging strategies, assessing whether a fixed battery range is sufficient or if dynamic sizing offers greater benefits. The analysis also investigates if the higher cost associated with batteries can be offset through savings on electricity tariffs and grid-related services. Results suggest that with strategic planning, larger batteries can enhance both operational flexibility and economic viability.