The 680 MW Nova Power Bank in California, one of the largest battery energy storage systems (BESS) in the world and the U.S., is gearing up completion of its final 60 MW construction phase. Once fully operational, with the fifth and final phase joining the preceding phases later this year, Calpine’s Nova will cement a new chapter in the currently shun renewable energy boom in the U.S.
Update on Latest Phase Completion
Last year, the story of Nova passed as one of promise. Calpine was preparing to bring 510 MW online in summer 2024, followed by a 110 MW phase in autumn and the final 60 MW stretch in this year while concurrently aiming for full project completion.
Currently, the first four phases – totaling 620 MW and 2,480 MWh – have been successfully completed and are operational, marking the major milestone in late September 2024. The fifth and final phase (60 MW / 240 MWh) of the Nova Power Bank project in California remains underway, with full commercial operation now firmly expected any time soon.
Nova Power Bank Factsheet
Location: Menifee, California (brownfield site)
Total Capacity: 680 MW / 2,720 MWh (all 5 phases)
Site Area: Over 43 acres + about 1,200 battery enclosures
Current Status: Phases I–IV completed in late September 2024 (620 MW / 2,480 MWh); Phase V (60 MW / 240 MWh) underway
Expected Full Operational-By Date: End of 2025
Technology Used: Lithium-ion battery enclosures (BYD Cube Pro)
EPC Contractor: Mortenson (through Project Labor Agreement)
Grid Connection: Three 500 kV substations linking to Southern California grid
Grid Uses: Daily charge/discharge cycles, voltage regulation
Repurposed Site: Former gas-fired power plant (Inland Empire Energy Center)
Homes Powered: Up to 680,000 homes for 4 hours
Why The Nova Power Bank BESS Project Matters
- Grid reliability. With over 2.4 GWh online, the Nova Power Bank is providing critical on-demand energy to Southern California Edison, San Diego Gas & Electric, and Peninsula Clean Energy; ensuring stability during peak usage and sunless seasonal intervals.
- Sustainability through reuse. The Nova Power Bank is built on the decommissioned Inland Empire Energy Center site. This allows for the repurposing of existing infrastructure spanning from foundations to substations – ultimately minimizing waste and accelerating deployment.
- Impact of scale. At 680 MW with a 4-hour discharge capability, California’s Nova can power about of 680,000 homes. This figure reflects Calpine’s ambition and market leadership in large-scale BESS projects. The project also boasts as one of the largest in the world and the states – straight outta California.
- Construction impact: The four phases of the Nova Power Bank have been completed under a Project Labor Agreement, and so will the final phase. Coupled with Mortenson’s execution with nearly 200 union craftworkers, it illustrates how community-driven construction models can actively support clean energy expansion.
Also read: Fluence & AGL Launch Australia’s Largest Grid‑Scale Battery: 500 MW / 2,000 MWh Tomago BESS
