The Bellefield Solar + Storage project is a large-scale energy development in Kern County, California, US. The project is being developed by AES Corporation and combines 1GW of solar photovoltaic (PV) generation with 1GW of lithium-ion battery storage, configured for four-hour discharge. It is projected to supply electricity to approximately 467,000 households annually.
The facility supports California’s renewable energy transition and grid decarbonisation objectives, aiming to address peak demand periods and improve grid stability.
Project Location
The project occupies approximately 8,300 acres of privately held land in California City and unincorporated areas of Kern County within the Mojave Desert. This region is already home to several large-scale renewable energy projects due to its solar irradiance and land availability.
A 14-mile generation tie line is under construction to connect Bellefield to the Southern California Edison Windhub Substation.
This new transmission line will enable the delivery of electricity to the California Independent System Operator (CAISO) grid, supporting energy supply across Southern California.
Bellefield Solar + Storage Project Capacity and Infrastructure
Bellefield is being built in two phases, each comprising 500MW of solar PV generation and 500MW of battery storage. The combined energy storage capacity will reach 2,000MWh.
The project infrastructure includes high-efficiency PV modules mounted on single-axis tracking systems, lithium-ion batteries housed in modular enclosures, central inverters, high-voltage transformers, and a control centre.
The modular battery layout supports phased commissioning and enables component replacement or upgrades as technology evolves. The battery systems will store excess solar energy generated during daylight and discharge it in the evening to meet peak grid demand.
Bellefield is expected to produce approximately 3.2 million MWh of electricity annually.
Development and Timeline
AES acquired the fully permitted project from Avantus in early 2023. Construction of Phase 1 began in the last quarter of 2023 and was completed in mid-2025.
This phase included full deployment of solar generation and battery systems along with associated transmission infrastructure. Phase 2 construction commenced in 2024 and is projected to conclude by late 2026.
Key development milestones included site clearance, grading, pile driving for solar panel structures, substation construction, and grid interconnection procedures.
All construction activities are being carried out in accordance with permitting conditions and interconnection requirements set by CAISO and the California Public Utilities Commission (CPUC).
Financing and Ownership
Bellefield is wholly owned and financed by AES. The company has not disclosed the total capital investment or funding partners. The financing model relies on long-term power purchase agreements and internal corporate investment.
Phase 1 is underpinned by a 15-year PPA with Amazon, which supports revenue stability. AES’s broader renewable energy portfolio comprises more than 10GW of installed and contracted capacity across multiple markets.
Bellefield Solar + Storage Project Technological Details
The facility uses solar PV modules with high energy conversion efficiency, mounted on single-axis trackers that follow the sun’s path to maximise generation.
The battery energy storage systems use lithium-ion chemistry, configured for four-hour discharge durations. These are housed in prefabricated containers that include integrated cooling systems and fire suppression.
AES’s Maximo robotic platform automates the lifting and placement of solar panels, enabling consistent installation quality across the large project footprint. A central control platform monitors system operations, collects real-time data, and manages dispatch to the grid. The integrated energy management system is designed to optimise both generation and storage for grid reliability.
Power Purchase Agreements
The first phase of Bellefield is supported by a long-term power purchase agreement signed with Amazon. The 15-year agreement is structured to provide fixed-price electricity to the buyer and long-term revenue to the project owner.
Contractors Involved
AES is overseeing all phases of the project, including engineering, procurement, construction, and long-term operations. The company deployed a proprietary robotic installation system, Maximo, to automate the placement of solar panels.
Maximo is designed to operate in desert conditions and is intended to reduce manual labour requirements during module installation.
Clark Bros, a California-based contractor, contributed to civil works and site infrastructure. Battery systems are primarily supplied by manufacturers in the US and South Korea. Additional subcontractors have been engaged for electrical installation, fencing, and environmental compliance.
