Tesla has signed a long-term power purchase agreement (PPA) with ContourGlobal for approximately 1 TWh of renewable electricity per year from Project Sterling, a hybrid solar photovoltaic (PV) and battery energy storage system (BESS) project in Arizona that is expected to become the largest renewable asset in ContourGlobal's portfolio.

According to ContourGlobal, the agreement covers around 90% of the project's annual electricity output and is one of the largest corporate PPAs for a single solar-plus-storage plant signed in the United States. The contract includes bundled electricity and renewable energy certificates (RECs).

Project Sterling combines 509 MWp (450 MWac) of solar PV with 360 MW / 1.4 GWh of battery energy storage, with an expected annual generation of more than 1.1 TWh. Under the agreement, Tesla will receive approximately 1,000 GWh (1 TWh) of renewable electricity per year.

Located in Arizona's Western Area Power Administration (WAPA) region, the project has firm point-to-point transmission rights into California's CAISO market and will be pseudo-tied, enabling it to supply electricity to Tesla.

ContourGlobal acquired the project in the development stage in December 2024 and said it has since redesigned it through its in-house business development, engineering, procurement and commercial teams to meet Tesla's requirements. Substantial construction activities began in 2025 through off-site physical works, including the procurement of major equipment in June. On-site construction is scheduled to begin in 2026, while commercial operation is targeted for 2028.

"This milestone represents a remarkable achievement of our commercial team," said Antonio Cammisecra, Chief Executive Officer of ContourGlobal. He added that the agreement is the company's largest PPA to date and described it as one of the largest renewable power purchase agreements of its kind in the United States.