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ContourGlobal breaks ground on 509 MW solar-plus-storage project in Arizona

ContourGlobal breaks ground on 509 MW solar-plus-storage project in Arizona

Built World

Tesla to buy most of the output from what will be ContourGlobal's largest renewable plant

Today: ContourGlobal breaks ground on Project Sterling

Overview

Updated 1 hour ago

A solar farm that has been in planning in one form or another since 2010 finally broke ground in the Mojave Desert. ContourGlobal is building Project Sterling about 20 miles north of Lake Havasu City, Arizona: 509 MW of solar panels paired with 1.4 GWh of batteries across 2,000 acres.

Tesla will buy about 90% of the output under a long-term power purchase agreement covering more than 1 TWh a year. That makes it one of the largest corporate solar-plus-storage deals from a single U.S. plant, and it lets the facility deliver clean power for up to 16 hours a day.

Why it matters

A plant this size shows how corporate buyers like Tesla are financing round-the-clock clean power, pushing solar past a daytime-only role.

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Key Indicators

509 MWp / 1.4 GWh
Solar capacity / battery storage
450 MWac of solar paired with 360 MW / 1.4 GWh of lithium iron phosphate batteries.
760,000+
Solar modules
Installed across the 2,000-acre site, with over 300 battery containers.
90%
Output contracted to Tesla
Long-term PPA covering more than 1 TWh of clean electricity per year.
400
Average construction jobs
Workers building the plant through 2028 in Mohave County.
~8.1
Site footprint
Roughly 2,000 acres in the Mojave Desert, one of the sunniest regions in the U.S.

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People Involved

Organizations Involved

Timeline

2010 March 2028

8 events Latest: Today
Tap a bar to jump to that date
  1. Commercial operation targeted

    Upcoming Target

    COD planned for Q1 2028, with the plant producing over 1.1 TWh annually.

  2. First energization planned

    Upcoming Target

    ContourGlobal targets initial energization in the third quarter of 2027.

  3. ContourGlobal breaks ground on Project Sterling

    Today Milestone

    Ceremony in Topock marks launch of 400-worker build of 509 MW solar, 1.4 GWh storage.

  4. On-site construction begins

    Construction

    Civil works and site logistics get underway in Mohave County, Arizona.

  5. Polaris Road construction starts

    Construction

    Work begins on the 5.2-mile access road connecting historic Route 66 to the site.

  6. Off-site work begins, major equipment procured

    Construction

    Long-lead items ordered while the project advances through permitting and design.

  7. ContourGlobal acquires Sterling at development stage

    Acquisition

    The company buys the project and begins reshaping its design around Tesla's requirements.

  8. Solar project first proposed near Golden Shores

    Planning

    A large-scale solar installation has been in planning in multiple variations since as early as 2010.

Scenarios

1

Project Sterling reaches commercial operation on schedule in Q1 2028

Likely Resolves by Q2 2028

Discussed by: ContourGlobal's published project timeline

If construction holds, first energization comes in Q3 2027 and full COD in Q1 2028. The plant then starts delivering roughly 1.1 TWh a year to Tesla and the western grid, becoming ContourGlobal's largest renewable asset.

2

Project Sterling construction slips past Q1 2028

Possible Resolves by End of 2028

Discussed by: Construction timelines tracked by PV Magazine and industry analysts

Construction began barely 18 months before the targeted COD. Supply chain, interconnection or labor delays could push energization and commercial operation later into 2028, deferring the Tesla deliveries.

3

Remaining Sterling output finds new buyers or merchant market

Possible Resolves by End of 2028

Discussed by: ContourGlobal (uncontracted output exposure)

About 10% of output sits outside the Tesla PPA. ContourGlobal could sign another offtaker or sell into the CAISO market through its WAPA transmission rights, adding revenue beyond the anchor contract.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

2023

Gemini Solar + Storage, Nevada (2023)

In Clark County, Nevada, the Gemini plant combined roughly 690 MW of solar with 380 MW / 1.4 GWh of battery storage under a power purchase agreement with NV Energy. It was then one of the largest solar-plus-storage plants in the U.S.

Then

Established a template for desert mega hybrid plants delivering power into evening hours.

Now

Proved that pairing utility-scale solar with storage at this size pencils out economically.

Why this matters now

Gemini used the same 1.4 GWh storage capacity as Sterling, showing the configuration already works at scale.

2024

Edwards Sanborn Solar + Storage, California (2024)

Terra-Gen completed a solar-plus-storage plant in Kern County, California with more than 3 GWh of batteries, the largest such array in the U.S., tied to contracts including Pacific Gas and Electric.

Then

Became the scale benchmark for solar-plus-storage in the U.S.

Now

Demonstrated multi-gigawatt-hour battery deployment as standard practice, not pilot territory.

Why this matters now

Sterling extends that scaling curve, but with a corporate offtaker (Tesla) instead of a regulated utility anchoring the project.

Sources

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