Tesla signed to buy about 1 TWh a year from an Arizona solar farm with a four-hour battery
ContourGlobal's Project Sterling: 509 MWp / 450 MWac solar plus 360 MW / 1.4 GWh storage, connected to WAPA with firm transmission rights into CAISO. Tesla takes about 1 TWh a year, roughly 90% of output, with bundled RECs. Operation targeted for 2028. Price and term not disclosed.
A big company that wants clean power around the clock has two choices: build it, or sign for it. Tesla signed.
On 28 July 2026, ContourGlobal said it had signed a long-term power agreement with Tesla for its Sterling project in Arizona. The project pairs 509 MWp (450 MWac) of solar with a 360 MW / 1.4 GWh battery, four hours at full power. Tesla will buy about 1 TWh a year, roughly 90% of the project's expected output of more than 1.1 TWh, with bundled renewable energy certificates.
Sterling connects to the Western Area Power Administration grid with firm transmission rights into CAISO, California's grid. Commercial operation is targeted for 2028. Price and contract term were not disclosed. Electrek reported the same day that Tesla also signed for the full 140 MWac of Zelestra's Lumen Farm solar project in Texas.
Analogy: it is a restaurant chain signing a long contract with one farm for most of its harvest, with a cold store built in so deliveries can come at dinner time too.
Good: a named buyer, a named size and a battery sized to shift solar into the evening. This is what a solar-plus-storage supply deal looks like at corporate scale.
Bad: no price and no term, so nobody else can use this as a benchmark. 2028 is two years out.
Ugly: deals this size need transmission rights most businesses cannot get. The structure does not shrink down to a single factory.
Source: ContourGlobal, 28 Jul 2026 - Tesla and ContourGlobal sign long-term power agreement for Sterling; Electrek, 28 Jul 2026 - Tesla Arizona solar and storage PPA. Four hours is desk division of 1.4 GWh by 360 MW.