Calpine has raised about $1 billion of debt for a single battery storage complex in Menifee, California. In early 2024 that made it the largest project-level battery financing in Leap's recent US records. Measured per megawatt, though, it sits in the lower half of its peers, and the reason lies in what the number does not tell you.
Key takeaways
- Calpine Corporation secured about $1 billion of debt financing, announced on 10 January 2024, through credit facilities under a syndicated loan for the 675 MW Menifee battery energy storage complex in Riverside County, California.
- The Menifee battery complex is being built in five phases: Menifee Power Bank I (230 MW), II (230 MW), III (50 MW), IV (110 MW) and V (55 MW).
- Construction of Calpine's Menifee battery storage complex began in August 2023, with commercial operation anticipated in October 2025.
- Calpine's $1 billion Menifee financing works out at about $1.48 million of debt per MW of battery capacity.
- White & Case LLP represented Calpine Corporation in the Menifee battery storage financing.
Why finance five batteries with one loan?
One syndicated loan for five phases trades flexibility for scale. A syndicated loan is a single facility provided by a group of banks, each taking a share, under one set of terms. For a borrower the size of Calpine, it is a way to raise a large sum without negotiating five separate packages.
The phases are uneven. Two account for 460 MW between them, while the smallest is 50 MW. Financed separately, the smaller phases would carry much the same legal and due diligence costs as the larger ones. Bundled, those costs are spread across the whole complex.
A single facility also smooths construction. Calpine can draw funds as each phase needs them rather than closing a new financing every time one is ready to build. With construction already under way since August 2023, the money follows the build schedule rather than leading it.
The trade-off is concentration. Lenders take exposure to one site, one owner and one construction programme. That suits a complex planned to be one of the largest battery systems in the US, where the sponsor's balance sheet and track record carry weight with lenders.
Where does Menifee rank among US battery financings?
By amount, it ranks first among the project-level storage financings Leap records for the period. Leap holds 15 US battery debt financings of at least $200 million announced between January 2023 and June 2024. Two other large amounts in that set fund manufacturing rather than storage projects: Redwood Materials' $2 billion and KORE Power's $850 million, both from the US Department of Energy.
Among project-level storage financings, the ranking by amount runs as follows:
- Calpine, Menifee, California: $1,000 million
- Plus Power, two Arizona projects: $701 million
- Plus Power, three Texas projects: $674.3 million
- Strata Clean Energy, 255 MW: $559 million
- Aypa Power, California and Texas: $550 million
- Recurrent Energy, Papago, Arizona: $513 million
The ranking by amount mostly reflects size. At 675 MW, Menifee is larger than any of the single-site batteries in that list, so it borrows more in total. The more telling measure is debt per megawatt.
Why does Menifee borrow less per megawatt than its peers?
Battery debt per megawatt depends heavily on duration, meaning how many hours a battery can sustain its full output. A four-hour battery holds twice the energy of a two-hour battery with the same power rating, and costs considerably more to build. More cost means more debt per megawatt.
The comparisons show this clearly. Clearway's Rosamond Central battery, rated at 147 MW and 588 MWh, raised $421 million, or about $2.86 million per MW. Recurrent Energy's 300 MW, 1,200 MWh Papago battery raised a $513 million package, about $1.71 million per MW, though that includes a $101 million letter of credit facility. Plus Power's three Texas batteries, all two-hour systems, raised $674.3 million for 700 MW, about $0.96 million per MW, as covered in how Plus Power split its Texas and Arizona battery financing.
Menifee's $1.48 million per MW sits between the two-hour Texas systems and the four-hour Californian and Arizonan ones. Leap's record does not state Menifee's energy capacity in MWh, so its duration cannot be confirmed from the data. That is the missing piece. Without it, the per megawatt figure cannot be read as either cheap or generous.
The financing structure matters too. Leap records Menifee's financing as debt under credit facilities, without separating construction loans, tax equity bridges or letters of credit. Papago's package, by contrast, is split into a $249 million construction and term loan, a $163 million tax equity bridge and the letter of credit facility. Packages built from different components do not compare cleanly line by line.
Enerdatics' data shows the spread across priced US battery financings in this window. Of the six project-level deals where both debt and megawatts are recorded, debt per MW runs from about $0.96 million for Plus Power's Texas batteries to about $2.86 million for Rosamond Central. Menifee, at about $1.48 million, ranks fifth of six. The largest loan in the set is therefore not the most leveraged per unit of capacity.
What does the Menifee loan signal for US battery storage finance?
It signals that lenders were willing to commit $1 billion to a single storage site in early 2024. None of the other project-level storage financings Leap records from 2023 reached that size. The Menifee loan moved battery debt into a scale more usually seen in large generation projects.
California's position helped. Leap tags Menifee to CAISO, the state's grid operator. Other Californian batteries financed in the period, such as Rosamond Central, which dispatches solar-generated electricity at peak demand under a long-term adequacy contract with Southern California Edison, show the kind of contracted revenue lenders look for.
The wider market has kept moving in the same direction. Later storage financings, such as Spearmint Energy's Red Egret package in Texas, have added preferred equity and tax credit transfer commitments to the capital stack, as described in how ERCOT battery storage financing is moving toward de-risked assets. Single, very large debt facilities like Menifee's are one route. Layered packages are another.
The open question is delivery. Commercial operation is planned for October 2025 across a five-phase build. Whether all phases reach operation on that timetable will determine how lenders view the next financing of this size.
Frequently asked questions
How much did Calpine raise for the Menifee battery project? About $1 billion of debt, through credit facilities under a syndicated loan, announced on 10 January 2024.
How large is the Menifee battery storage complex? 675 MW across five phases in Menifee, Riverside County, California, ranging from 50 MW to 230 MW each.
When will the Menifee battery complex be operational? Construction began in August 2023, and commercial operation is anticipated in October 2025.
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