Clearway Energy Group, LLC (CEG) has negotiated two energy storage tolling agreements with investor-owned utility (IOU) San Diego Gas & Electric (SDG&E) for offtake from one of its solar and storage complexes in Kern County, California.
Although each agreement is similarly sized when it comes to capacity, they interestingly have different durations, with one portion capable of 4-hour discharge duration and the other a longer 8-hour duration.
The news caps off what’s been an active year for CEG, who earlier this year announced over US$1billion in credit facilities as reported by Energy-Storage.news.
Owned by Global Infrastructure Partners (GIP) and TotalEnergies, CEG has one of North America’s largest energy storage portfolios, with a claimed 10.7GW of operational and in-development BESS capacity across 16 US states.
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Rosamond South II
As detailed within filings submitted with the California Public Utilities Commission (CPUC), SDG&E has negotiated two tolling agreements with CEG-owned subsidiary Golden Fields Solar VI, LLC for offtake from two portions of the developer’s Rosamond South complex.
Specifically, under the two 15-year agreements, SDG&E will have access to a 44MW/176MWh portion, along with a longer duration and slightly higher output 48MW/384MWh portion of the Rosamond South II project.
This second portion of the project builds upon Rosamond South 1, which pairs a 140MW solar farm with a 117MW BESS, that was recently brought online by the developer. Offtakers for the first portion include community choice aggregator (CCA) Marin Clean Energy (MCE), The University of California Constellation Energy as well as three municipal utilities.
As reported by Energy-Storage.news, CEG secured financing to commence construction on the first portion of the project during 2024.
The two new offtake agreements are a result of SDG&E’s Phase 3 Integrated Resource Planning Reliability Request for Offers (Tranche 3 RFO), which was first launched in March 2024 and sought to address the utility’s capacity requirements between 2025 and 2031.
Given the turbulent state of the renewable energy industry during the past year and after compiling a shortlist of submissions, SDG&E reopened the RFO to give applicants an opportunity to resubmit bids with refreshed pricing and project characteristics.
“Each of the shortlisted projects negotiated price adjustments to address impacts from the tariff and potential tax incentives changes since the time when bids were submitted,” said SDG&E as part of its recent submission with the CPUC.
Both portions of CEG’s Rosamond South II project are expected to utilise lithium-ion battery storage and be online prior to 1 June 2027, with the developer targeting financial close and NTP sometime during the final quarter of next year.
SDG&E has asked the CPUC to approve the two agreements no later than 1 March 2026.
Sale to own yieldco
In related news, it was revealed at the end of last month that CEG had agreed to sell the Rosamond South II project to its publicly traded yieldco Clearway Energy, Inc. (CWEN) for a base purchase price of around US$45.7 million.
Similar to the structure of most large independent power producers (IPPs), projects nearing commercial operations developed by CEG are often sold to CWEN as a way of sheltering investors from early-stage development risk.
CWEN revealed details of the purchase agreement in an 8-K filing submitted with the US Securities and Exchange Commission (SEC) on 24 November.
CEG has also agreed to sell Spindle Storage, a 199MW BESS located in Weld County, Colorado, for around US$45.7 million to CWEN. This project has a 20-year offtake agreement with Public Service Company of Colorado and is due online sometime next year.
The transaction of both projects is expected to close during the second half of 2026.
