Background: As part of its commitment to global climate goals, Indonesia is pursuing a dual strategy of decarbonizing its transport and power sectors through the adoption of electric vehicles (EVs) and the expansion of renewable energy (RE). However, the uncoordinated charging of a large EV fleet combined with the intermittency of renewables like solar and wind poses significant challenges to the stability and efficiency of the national electrical grid. This study investigates the potential for controlled EV charging and Vehicle-to-Grid (V2G) technology to mitigate these challenges and facilitate a synergistic energy transition.

Methods: We developed a detailed hourly power system dispatch optimization model for Indonesia’s Java-Bali grid, which accounts for over 70% of the nation's electricity demand. Using technical and economic data from national plans and international databases, we simulated grid operations for the year 2030 under four distinct scenarios: a Business-as-Usual (BAU) case, a High RE case, a High EV penetration with Smart Charging case, and a High EV with V2G capability case. The model's objective was to minimize total system operating costs while meeting demand and respecting all operational constraints.

Results: The modeling results demonstrate that uncontrolled EV charging in a high-RE system significantly increases peak demand and leads to substantial RE curtailment. In contrast, the implementation of smart charging shifts EV load to periods of high RE generation, reducing curtailment by up to 75% and lowering total system costs. The V2G scenario provides further benefits by using the EV fleet as a distributed energy resource, reducing the need for expensive fossil-fuel-based peaker plants and decreasing power sector CO2 emissions by an additional 12% compared to the uncontrolled charging scenario.

Conclusion: The strategic integration of electric vehicles, particularly through smart charging and V2G frameworks, is critical for enabling a cost-effective and reliable transition to a renewable-energy-dominated power system in Indonesia. The findings underscore the urgent need for policymakers to develop supportive regulatory frameworks, dynamic electricity tariffs, and smart grid infrastructure to unlock the full potential of EV-grid integration.