Solmar Insights
EDP Renewables North America has completed the Sandrini Energy Storage system, a 92 MW/368 MWh battery storage facility jointly sited with the 300 MW Sandrini Solar project in Kern County, California. The Redwood Coast Energy Authority has contracted 100 percent of the battery storage capacity as well as 100 MW of the solar generation, positioning the project as a key contributor to local grid reliability and clean energy delivery.
Key figures
92 MW/368 MWh battery storage system
300 MW Sandrini Solar capacity
100% battery and 100 MW solar capacity contracted to RCEA
Project scope and key participants
The Sandrini Energy Storage system, delivered by EDP Renewables North America (EDPR NA), enhances the capabilities of the existing Sandrini Solar site. Located in Kern County, a region with significant renewable energy infrastructure, this project increases the local battery storage footprint with a 92 MW/368 MWh facility. The addition reflects growing demand for firm, predictable renewable output in California’s power markets, where solar penetration drives periods of oversupply and curtailment absent storage.
The Redwood Coast Energy Authority (RCEA), a community choice aggregator serving Humboldt County, has contracted for the entire output of the storage unit and a significant share of the co-located solar generation. This structure gives RCEA reliable access to dispatchable renewable energy, fulfilling both regulatory requirements and customer demand for clean power procurement.
EDPR NA has now reached 1.23 GW of renewable capacity installed across wind, solar, and battery assets in California, with a reported ability to supply power to over 485,000 homes statewide. RCEA’s offtake agreement demonstrates the growing role of regional public agencies in contracting long-term energy storage supply to strengthen local grid flexibility.
The Sandrini project has also brought local economic benefits, generating an estimated $5 million in local revenue to support public infrastructure and sustaining approximately 50 jobs during its construction phase.
Battery storage mechanics and grid integration
The co-location of large-scale battery storage with solar generation enables storage to capture energy during periods of solar surplus and deliver it when grid demand peaks, often in the evening hours. The Sandrini system’s 92 MW capacity paired with 368 MWh of storage duration is configured for a 4-hour discharge window, matching the prevailing format used for renewable integration in California ISO territory.
This battery storage design helps smooth volatility in grid operations caused by the state’s high solar deployment, including sharp evening ramps and risk of curtailment in midday hours. Locational value is enhanced by the site’s proximity to major regional transmission corridors and its integration into established interconnection infrastructure already serving the Sandrini Solar project.
Grid operators and regulators have increasingly called for projects like this to provide resource adequacy and ancillary services. The complete offtake arrangement with RCEA ensures that the battery resource can be scheduled and dispatched to meet the aggregator’s load obligations, as well as contribute to broader grid reliability goals across the region.
By contracting the full battery output, RCEA is in a position to align real-time renewable supply with consumer demand and grid operator requirements. The technical and commercial arrangement here exemplifies the direction of modern grid flexibility strategies for high-renewable systems, with BESS paired directly to variable generation under long-term energy storage service agreements.
Offtake agreement structure
The Sandrini Energy Storage arrangement is structured around a full-capacity energy storage service agreement (ESSA) with RCEA for 100 percent of the 92 MW/368 MWh battery system, and a portion of the solar site’s output (100 MW). These types of offtake agreements typically feature fixed or indexed payment mechanisms over a multiyear term, providing predictable revenue for the renewable operator and a hedge against volatility for the aggregator.
Energy storage service agreements enable offtakers like RCEA to schedule and dispatch storage capacity as needed, responding to both local loads and ISO grid signals. These contracts may also bundle additionally qualified services such as frequency regulation, capacity, and spinning reserve support, although these particular elements were not detailed in the source.
By securing both solar and storage through a single commercial structure, RCEA advances its procurement of new, clean firm capacity without assuming direct technology or operational risk. At the same time, EDPR secures a creditworthy, public-sector customer for the life of the asset, supporting long-term portfolio financeability and bankability.
This deal model reflects ongoing trends in the California market, where energy agencies and CCAs are increasingly signing hybrid solar-plus-storage contracts to address time-of-day price risk and resource adequacy compliance under current policy frameworks.
Market context and policy drivers
California’s policy environment continues to favor accelerated deployment of energy storage and renewable generation. Regulatory mandates for renewables, resource adequacy, and emissions reduction are driving significant procurement by utilities and CCAs. Pairing storage with solar facilities like Sandrini enables compliance with hourly clean energy requirements and mitigates the system-level risks associated with high renewable penetration.
The addition of the Sandrini Energy Storage project fits within California’s ongoing grid modernization and reliability push, particularly as legacy thermal assets retire and more demand is electrified. Recent calls from the California Public Utilities Commission (CPUC) and the California Independent System Operator (CAISO) for additional storage resources have seen developers accelerate project delivery and offtakers seek out bundled hybrid agreements for operational certainty.
By integrating storage at the point of solar generation, the grid benefits from localized resource flexibility and reduced need for additional network upgrades. This model is increasingly seen as a path to address both near-term resource adequacy and longer term decarbonization trajectories specified by state targets.
Within this regulatory and economic context, the Sandrini project exemplifies the scale and type of asset now prioritized by institutional investors, public buyers, and developers moving to aggregate renewable and storage offerings for reliability and policy compliance.
Financial and regional impacts
Beyond meeting renewable and storage policy objectives, the Sandrini project’s impact extends into local revenues and employment. According to EDPR NA, the project is expected to generate approximately $5 million in revenue for Kern County over its operating life, earmarked for infrastructure enhancements including schools, roads, and emergency services.
Jobs created during the construction phase totaled around 50, with additional permanent jobs likely in site operations and maintenance. The fiscal contribution to public budgets and community infrastructure underscores the multilevel value proposition presented by new grid-scale energy investment.
Regionally, Kern County has played a central role in California’s energy transition, hosting a concentration of wind, solar, and now large battery storage installations. The integration of storage with substantial existing solar assets provides a replicable blueprint for other Western US markets grappling with the operational and financial challenges of renewable variability.
As policy attention continues to focus on the capacity, resilience, and equity benefits of renewable infrastructure, projects like Sandrini are likely to inform further procurement, siting, and funding strategies for energy buyers and municipal authorities.
What this means for buyers
This project offers a workable model for structuring full-capacity battery storage service agreements tied to municipal and community energy procurement needs. Institutional buyers and public agencies looking to firm renewable output can look to the Sandrini arrangement for insight into scalable hybrid offtake contracts that address both grid reliability and regulatory requirements. The deployment underscores the investment case for co-located storage and renewables in regions facing high solar penetration and shifting grid demands. Sandrini supports both clean energy targets and revenue streams benefiting local infrastructure, making similar projects attractive for diverse stakeholders.
