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Receive a presentation on the status of the draft Battery Energy Storage System (BESS) ordinance; Provide feedback and direction on proposed ordinance provisions; Direct staff to proceed with final ordinance preparation and public hearing scheduling
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Published Notice Required? Yes ____ No _X _
Public Hearing Required? Yes ____ No _X _
DEPARTMENTAL RECOMMENDATION:
The Department of Resource Management recommends that the Board of Supervisors:
1. Receive a presentation on the status of the draft Battery Energy Storage System (BESS) ordinance;
2. Provide feedback and direction on the proposed ordinance provisions, including key policy decisions regarding prime agricultural land regulations and setback standards; and
3. Direct staff to proceed with final ordinance preparation and public hearing scheduling.
SUMMARY:
Since implementing the BESS moratorium in January 2024, the Department of Resource Management has undertaken an extensive consultation process to develop comprehensive regulations for Battery Energy Storage Systems in unincorporated Solano County. This effort has been informed by the BESS Technical Working Group, composed of local first responders, industry experts, and community representatives, and has included consultation with national safety organizations and other jurisdictions with BESS experience. The draft ordinance reflects feedback from the groups and strives for a careful balance between advancing renewable energy goals and ensuring robust public safety protections. Development of the draft ordinance has reached a stage where Board feedback would be timely as final ordinance provisions are developed. The draft ordinance is supplemented by an additional regulatory document developed by Solano Office of Emergency Services, the Battery Energy Storage System Emergency Response Plan Guidance (Attachment B). In order to adopt an ordinance before the expiration of the current moratorium on BESS, the ordinance must be approved by the Board of Supervisors prior to December 23, 2025.
FINANCIAL IMPACT:
The cost for preparation of this staff report and ongoing ordinance development activities are included in the Department of Resource Management's FY2025/26 Working Budget. Future implementation costs for technical review, inspection, and enforcement activities will be recovered through established fee structures and applicant-funded technical review processes.
DISCUSSION:
Background and Process
Following the Board of Supervisors' January 23, 2024 decision to implement a two-year moratorium on front-of-the-meter BESS facilities, staff initiated a comprehensive ordinance development process. This moratorium was extended through January 23, 2026, providing time to develop land use standards ensuring public safety, health and welfare.
Technical Working Group Consultation
Staff established a Technical Working Group consisting of stakeholders from various sectors who meet monthly to advise on ordinance development. The Working Group includes:
• Priscilla Yeaney: Solano County Assistant Agriculture Commissioner
• Alfred Abruzzini: Fire Chief Representative
• Robyn Rains: Solano County Emergency Services Manager
• Scott Murtishaw: California Energy Storage Alliance Executive Director
• Sarah Dunn: Community Member
• Chris Ambrose: Solano County Environmental Health, Hazardous Materials
The Technical Working Group has conducted extensive interviews with national experts representing key organizations including:
• National Fire Protection Association (NFPA): Developers of NFPA 855, the Standard for Installation of Stationary Energy Storage Systems, which provides comprehensive requirements for BESS safety and addresses thermal runaway risks
• Underwriters Laboratories (UL): Creators of UL 9540 and UL 9540A standards, which establish safety requirements for energy storage systems and large-scale fire testing protocols
• Electric Power Research Institute (EPRI): Leading research organization conducting battery storage fire safety research and maintaining the BESS Failure Incident Database
• Hiller Companies: Fire protection specialists with extensive BESS expertise who contribute to NFPA 855 Committee leadership and provide industry best practices
Coordination with Regional Partners
Staff has engaged in discussions with regional partners to learn from best practices and shared experiences:
City of Vacaville Partnership: Staff has worked closely with the City of Vacaville, which initiated its own BESS ordinance development process and moratorium implemented in May 2024. This coordination has provided valuable insights into municipal approaches to BESS regulation and shared technical resources.
Other County Consultation: Staff has consulted with other California counties that have experienced BESS thermal runaway incidents and developed regulatory responses, including:
• San Diego County: Following two significant BESS fires in 2023-2024, San Diego County developed comprehensive safety standards and technical study requirements.
• Monterey County: Following the Moss Landing incidents, including the January 2025 fire that evacuated 1,200-1,500 residents, Monterey County has enhanced emergency response protocols.
• Kern County: Significant experience permitting large scale BESS through local permitting processes and the AB 205 Opt-In Process.
AB 205 Permitting Process Insights
Staff has gained valuable insights from counties currently navigating the AB 205 "opt-in" permitting process, which allows developers to bypass local permitting through direct California Energy Commission approval. This process has informed the development of local standards that remain relevant regardless of permitting pathway, including local ordinances and regulations (LORS) as the CEC process still requires county input and comment. For example, the Ag Mitigation Ordinance is a LORS that the State would considere during any application going through the AB205 “opt-in” process.
Zoning
The draft BESS Ordinance proposes to regulate the siting of Battery Energy Storage Systems (BESS) in specific zoning districts within Solano County. The intent is to balance energy infrastructure needs with appropriate land use compatibility. BESS facilities are not permitted in Very High and High Fire risk areas. BESS projects are proposed to be permitted in the following zoning districts, subject to further permitting requirements: A-20, A-40, A-80, A-160, C-S, M-L, M-G-1/2, M-G-3, I-WD
Key Policy Decisions for Board Direction
Prime Agricultural Land Regulations
The draft ordinance presents several options for addressing BESS development on prime agricultural land:
Option 1 (Staff Recommendation): Complete prohibition on prime agricultural land, unique agricultural land, or land of statewide importance
Option 2: Allow BESS facilities to occupy up to 45% of a parcel's prime agricultural land
Option 3: Allow BESS facilities on prime agricultural land only if they demonstrate benefit to local agriculture, nearby farmers, or food production
Setback Standards
The draft ordinance includes multiple setback options reflecting different risk tolerance levels:
Option 1: Distance-based requirements with 300-foot setbacks from sensitive receptors such as hospitals, schools, etc. and variable property line setbacks based on property line length
Option 2: Reliance on NFPA 855 and state requirements only
Option 3: Uniform 50-foot setbacks from all property lines
Option 4: Uniform 300-foot setbacks from all property lines
Option 5 (Staff Recommendation): Risk-based approach with different requirements based on thermal runaway risk determination
The staff recommendation incorporates thermal runaway risk assessment as the determining factor for setback requirements, with more stringent standards for higher-risk battery technologies.
Option 5 (Staff Recommendation)
If a risk of thermal runaway is determined as defined in E1 of the draft ordinance (Attachment A) the following setback standards apply:
(a) The minimum distance of a BESS module from any existing sensitive receptor as defined in California Health and Safety Code § 42705.5(a)(5) is 300 ft.
(b) A 30-foot-wide fire rated access road must encircle the entire module array inside security perimeter fence. There must be at minimum two entrances to the access road.
(c) Setbacks from the front property line to the first BESS module are minimum 100 feet.
(d) Setbacks from the rear and side property line to the first BESS module are minimum 50 feet.
(e) Property owners and residents residing on the same parcel as a BESS facility can exempt their buildings from distance requirements 3b and 3c with written approval contained in the project application.
If no risk of thermal runaway is determined as described in E1 (b), State standards and a minimum setback of 20 feet from all property lines to the first BESS module are acceptable.
Public Safety Considerations
The draft ordinance addresses significant public safety concerns raised by thermal runaway incidents. Recent incidents in California, including the Gateway Energy Storage facility fire in San Diego County that burned for two weeks and the Moss Landing incident that required large-scale evacuations, have highlighted the need for comprehensive safety measures. These systems would not be permitted under the draft ordinance due to a ban on indoor systems, the factor that led to these incidents' outsized impact.
The ordinance incorporates lessons learned from these incidents, including requirements for:
• Comprehensive emergency response planning
• First responder training and equipment funding
• Air quality monitoring systems
• Technical studies by third-party experts
ALTERNATIVES:
1. Direct the Department to proceed with the current draft ordinance without modifications: This would expedite the process but may not address all Board priorities or community concerns.
2. Request additional stakeholder consultation before final ordinance preparation: This would provide more public input but would extend the timeline for ordinance completion.
3. Implement more restrictive standards than currently proposed: This would provide enhanced safety measures but might push applicants to receive their permits from the California Energy Commission.
OTHER AGENCY INVOLVEMENT:
Staff has worked with the Solano County Office of Emergency Services, the Agricultural Commissioner’s Office, the representative of the unincorporated fire districts, and CAL FIRE.
CAO RECOMMENDATION:
APPROVE DEPARTMENTAL RECOMMENDATION