In Oakland, California, a fleet of 74 electric school buses has spent two years feeding electricity back into the grid during evening peak hours. The buses charge overnight, use only 20–40% of their battery during the day, then plug into vehicle-to-grid (V2G) chargers after school to discharge power just as home energy demand rises. The chargers are built by Tellus Power and the project is operated by Zum.
Together, the buses hold 11.5 MWh of storage and can discharge at 2 MW, enough to power roughly 1,000 homes. Over the past two years, the fleet has returned 1.7 GWh to the grid with over 99.5% uptime, earning hundreds of thousands of dollars through energy arbitrage—buying power when cheap and selling when expensive. Tellus describes the fleet as a small, reliable peaker plant.
Tellus says fleet V2G installations can be deployed in months, compared to years for conventional power plants, and its chargers avoid the need for large on-site transformers. Similar projects are underway in Vermont, Illinois, British Columbia, and San Francisco, with a 104-bus fleet scaling to 238. The company is also eyeing electric trash trucks as the next candidates for V2G revenue.