California’s ‘biggest hybrid renewable power plant’ under construction, Clearway says

By Andy Colthorpe

October 27, 2021

Construction activity underway at the site. Clearway began work in late September before officially announcing the start of construction in a press release on 19 October. Image: Clearway via Twitter.

Construction of the first phase of what has been described as California’s biggest hybrid renewables-plus-storage project got underway earlier this month.

Combining 482MW of solar PV with 394MW of battery energy storage in total, utility-scale clean energy project developer Clearway’s Daggett project is being built adjacent to Coolwater Generating Station, a retired coal and natural gas power plant in San Bernadino, California.

On 19 October, Clearway said Daggett 3 Solar Power + Battery Energy Storage System (BESS) began full construction. Five different off-takers are contracted for the output of Daggett 3 and the Daggett 2 BESS.

They include California investor-owned utility (IOU) Pacific Gas & Electric (PG&E), which signed 15-year contracts to procure 46MW / 184MWh of output and capacity from Daggett 2 and 15MW / 60MWh from Daggett 3, Energy-Storage.news reported in December 2020. The contracts were part of a procurement of 387MW / 1,548MWh of battery storage made by the utility.

The other off-takers are Constellation, an energy supplier subsidiary of major US utility Exelon, and three not-for-profit Community Choice Aggregator (CCA) energy suppliers, Clean Power Alliance, East Bay Community Energy and MCE. Regular readers of the site will know that CCAs have become prolific signatories of off-take contracts with solar and solar-plus-storage facilities in California, offering their member-customers the choice of buying clean energy.

Clearway, which develops utility-scale solar and wind as well as community solar projects and now solar-plus-storage, broke ground on two projects totalling 76MW of solar PV with 75MW / 300MWh of battery storage on the Hawaiian island of Oahu in April, before then achieving financial close on the pair in July.

In a recent contributed article for our quarterly journal PV Tech Power, researcher Will Gorman from Lawrence Berkeley National Laboratory (Berkeley Lab) offered some findings from analysis into the hybridisation of solar or wind power plants with battery storage.

Gorman said Berkeley Lab’s work had shown that while hybrid power plants, particularly solar-plus-storage, are enjoying a rapid rise in the US, there can be multiple factors that come into play when determining whether such combined or colocated facilities make the most sense from economic and technical perspectives versus standalone battery or generation projects.

Currently the biggest single-site battery project which will be charged directly from a solar array under construction in the US is Manatee Energy Storage Center in Florida. Utility Florida Power & Light is building the 409MW / 900MWh battery system at the site of an existing utility-scale solar PV plant.

Meanwhile California’s biggest standalone battery project in operation is also the world’s biggest to date. Moss Landing Energy Storage Facility in Monterey County is a 400MW / 1,600MWh facility built in two phases and brought online by power generation and retail company Vistra Energy. The Moss Landing project was partially taken offline in September, not long after its inauguration, due to a battery module overheating incident which is still thought to be undergoing assessment.