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Conduct a noticed Public Hearing to consider adoption of an ordinance for Zone Text Amendment ZT-25-02 to amend Chapter 28 of the Solano County Code to revise and update regulations pertaining to Battery Energy Storage Systems within unincorporated Solano County; the project is exempt from the California Environmental Quality Act (CEQA) pursuant to Sections 15061(b)(3), 15307, and 15308 of the CEQA Guidelines
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Published Notice Required? Yes _X__ No __ _
Public Hearing Required? Yes _X__ No __ _
DEPARTMENTAL RECOMMENDATION:
The Department of Resource Management recommends that the Board of Supervisors:
1. Read the proposed ordinance by title only and waive further reading by majority vote;
2. Conduct a noticed public hearing to consider Zone Text Amendment ZT-25-02; and
3. Adopt the proposed ordinance Zone Text Amendment No. ZT-25-02 amending Chapter 28 of the Solano County Code to revise and update regulations pertaining to Battery Energy Storage Systems within unincorporated Solano County (Attachment A).
SUMMARY:
The matter before the Board of Supervisors involves proposed amendments to Chapter 28 of the Solano County Code (Zoning Regulations) to revise and update regulations related to Battery Energy Storage Systems (BESS), specifically “front-of-the-meter” BESS, in the unincorporated area of Solano County. In general, “front-of-the-meter” BESS facilities are directly connected to the transmission or distribution grid and primarily serve wholesale market functions. They collect energy from the grid, store it, and then discharge that energy later to provide electricity or other grid services when needed.
Current Solano County Zoning Regulations allow “front-of-the-meter” BESS (hereinafter simply referred to as “BESS”), in all zoning districts in the County with a Use Permit as “utility facilities or infrastructure, outside of right-of-way.” The current Zoning Regulations do not contain any specific standards for BESS facilities, with only the general development standards applicable to all land uses in the County applied.
Department staff recommend proposed updates to the Zoning Regulations as follows:
• Define BESS as its own unique land use and exclude BESS from the definition of “utility facilities or infrastructure, outside of right-of-way.”
• Allow BESS only in certain Manufacturing, Industrial and Commercial zoning districts.
• Define and implement BESS-specific development standards, including land use and siting standards, safety and setback requirements, technology assessment and risk management, impact mitigation/safety measures, permitting/review and decommissioning.
FINANCIAL IMPACT:
The cost for preparation of this staff report and ongoing ordinance development activities are included in the Department’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:
Concerns with BESS facilities
There have been several recent fires at BESS facilities nationwide, including multiple in California. Some of these fires have resulted in shelter-in-place orders being issued for nearby residents and communities. There are several different and emerging battery technologies that BESS facilities may utilize, which present different risks. Lithium-ion batteries, often the preferred battery technology by BESS developers, present a risk of fire and thermal runaways that can be caused by impacts, puncture or mechanical damage, including overcharging, overheating, and short circuits. Contamination of groundwater has also resulted from fire suppression or from facility operations related to BESS facilities. BESS facilities have also generated concerns related to plume size and air quality, aesthetics, conversation of agricultural land, traffic, and operational noise, among other things.
Solano County Temporary Moratorium on BESS Facilities
In June 2023, the County received a use permit application for a proposed BESS facility on land with an Exclusive Agriculture (A-40) zoning designation that, if approved, would become one of the largest BESS projects in the State. Under current Zoning Regulations, this facility would be allowed under issuance of a Conditional Use Permit under the “utility facilities or infrastructure, outside of right-of-way” land use, without any specific standards in place to address the complexities and significant safety risks associated with BESS technology.
At its December 5, 2023, meeting, the Board of Supervisors directed staff to prepare an urgency ordinance to temporarily prohibit approval of new BESS facilities in unincorporated Solano County while permanent regulations were developed. On January 23, 2024, the Board adopted Interim Ordinance No. 2024-1852-U as an urgency measure under Government Code §65858 to prohibit new front-of-the-meter BESS facilities in Solano County for a 45-day period. On February 27, 2024, the Board extended the Interim Ordinance for 22 months and 15 days. The Ordinance is set to expire on January 23, 2026, unless repealed prior to that date.
On August 26, 2025, the Board adopted Amendment No. 1 to the Interim Ordinance lifting the moratorium on front-of-the-meter BESS projects in Manufacturing and Industrial zoning districts where specific new safety, siting and operational standards could be applied to alleviate the immediate threat to public health and safety. The Board left the moratorium in place for all other zoning districts, allowing staff additional time to evaluate the additional risks of BESS facilities in those areas and develop appropriate regulations.
Public and Stakeholder Engagement
Technical Working Group Formed, March 2024: County staff formed a Technical Working Group (TWG) comprised of expert and local stakeholders representing the Solano County Sheriff’s Office/Office of Emergency Services, Fire Protection District Fire Chiefs, the Solano County Environmental Health Division (Hazardous Materials section), the Solano County Agricultural Commissioner, the California Energy Storage Alliance and members of the public. The TWG generally met monthly from March 2024 through June 26, 2025. The TWG met with national experts on best practices related to BESS facilities, including experts from the National Fire Protection Association, Underwriters Laboratories, and Hiller Companies to discuss best practices in fire protection and impact mitigation. The TWG also provided feedback on preliminary drafts of this ordinance.
Public Workshop, July 18, 2024: The Solano County Planning Division hosted a public workshop to gather input on BESS regulations where staff discussed BESS technology, potential community impacts, and Assembly Bill 205's alternative "Opt-In" permitting process. Residents voiced concerns about facility proximity to homes and schools (particularly near the Vaca-Dixon substation), requested taxpayer protections through revenue sharing and independent safety monitoring, emphasized cybersecurity and domestic manufacturing requirements, and advocated for safer battery chemistries like iron flow or graphene over lithium-ion, with many suggesting alternative locations such as Lambie Industrial Park to maintain grid connectivity while avoiding residential proximity issues.
Board of Supervisors Input, August 12, 2025: County staff gave a presentation on ordinance development and solicited input on setback standards and agricultural land protection. Comments from the Board highlighted the need to develop comprehensive regulations to protect public health and safety, as well as the County’s environment and natural resources (including agriculture), while appropriately advancing clean energy development in the unincorporated area. Staff received direction to amend the existing Interim Ordinance No. 2024-1852-U and proceed with returning with a permanent ordinance language for consideration.
Planning Commission Public Hearing, September 18, 2025: Adopted a resolution recommending the Board of Supervisors adopt the proposed ordinance language.
Airport Land Use Committee Public Hearing, October 9, 2025: Adopted a resolution recommending the Board of Supervisors adopt the proposed ordinance language.
Summary of Proposed Ordinance Language
Definition and Scope: The ordinance adds a definition of Battery Energy Storage System (BESS) as an electrochemical device with a rated capacity of 1,000 kilowatt hours or greater that charges, stores, and discharges energy. The regulations apply only to front-of-the-meter (FTM) BESS in unincorporated Solano County and do not regulate behind-the-meter systems supporting residential, commercial, agricultural and industrial uses.
Land Use and Siting Standards: BESS facilities are permitted only in specific zoning districts with a Use Permit and are subject to exclusions from High and Very High Fire Hazard Severity Zones as determined by Cal Fire. The zoning districts where BESS are permitted are the Manufacturing and Industrial (M-L, M-G, I-WD, I-AS) and Commercial (C-S) districts. FEMA-designated floodplains require elevation at least two feet above Base Flood Elevation with appropriate flood protection measures and CLOMR approval. The ordinance prohibits BESS in all Agricultural, Residential, Resource Conservation and Park zoning districts.
Safety and Setback Requirements: For battery technologies determined to pose thermal runaway risks, minimum setbacks include 300 feet from sensitive receptors, 100 feet from front property lines, 50 feet from rear and side property lines and a 30-foot fire access road encircling the facility. Systems determined to pose no thermal runaway risk require only 20-foot setbacks from all property lines. All facilities must include 10-foot non-scalable perimeter fencing, 24/7 security monitoring and comprehensive signage with emergency contact information.
Technology Assessment and Risk Management: The ordinance requires third-party documentation evaluating thermal runaway risk for all proposed battery technologies. Systems posing thermal runaway risks must submit comprehensive technology comparison analyses, thermal runaway plume modeling and hazard mitigation analyses. Systems posing thermal runaway risks are not allowed in the Commercial zoning districts. Facility owners bear financial responsibility for emergency response costs, root cause analyses, environmental damage assessments and remediation following thermal runaway incidents.
Impact Mitigation and Safety Measures: Required measures include annual contributions for fire response equipment and emergency response training, radio interoperability support, air monitoring systems with ten or more permanent monitors, and comprehensive annual reporting to County staff. Technical studies by County-selected third-party experts must address fire safety, plume modeling, toxic gas dispersion, impacts to Travis Air Force Base flight paths and environmental hazards. BESS facilities will be required to comply with the County’s Agricultural Mitigation Ordinance.
Permitting and Review Process: BESS facilities will require County approval of a Use Permit. Applications will also be subject to CEQA. Application will require pre-application meetings with County staff and third-party experts, technical review fee payments, and public hearings before the Planning Commission (which will make a recommendation on the application) and the Board of Supervisors (for final approval or denial). Building permit documentation must include electrical diagrams, equipment specifications, commissioning reports, large-scale fire testing results, soil and air quality baseline testing and fault line analysis.
Decommissioning Requirements: The ordinance mandates comprehensive decommissioning plans including financial assurance through bonds or letters of credit equal to full decommissioning costs minus salvage value. Financial assurance must be posted in increments (100% by commercial operation start) with manufacturer responsibility agreements for battery cell recovery and recycling.
General Plan Consistency
The proposed ordinance is consistent with the Solano County General Plan in that the amendments establish regulations for emerging energy infrastructure technology while maintaining compatibility with the objectives, policies, general land uses, and programs specified in the plan. The ordinance supports renewable energy goals while protecting public health, safety, and welfare, and protecting the County’s environment and natural resources, including agricultural land, consistent with General Plan policies (SS.I-13, RS.G-5, RS.P-52, RS.P-53, RS.P-57, RS.P-58).
Environmental Review
The proposed ordinance is exempt from the California Environmental Quality Act (CEQA) pursuant to CEQA Guidelines §15061(b)(3) (it can be seen with certainty that there is no possibility the activity in question may have a significant effect on the environment), §15307 (Class 7 categorical exemption for regulatory activity to assure the protection of natural resources), and §15308 (Class 8 categorical exemption for regulatory activity to assure the protection of the environment).
Under current Zoning Regulations, front-of-the-meter BESS facilities are allowed in all zoning districts in unincorporated Solano County as “utility facility or infrastructure, outside of R.O.W.” This general land use category has no BESS-specific development standards to protect human health, safety, and welfare, as well as the county’s natural resources and the environment, which may be impacted by the siting of front-of-the-meter BESS. This Ordinance will not change existing conditions, other than to limit the placement of front-of-the-meter BESS facilities to those zoning districts that present the most conducive environment for safe placement consistent with the County’s General Plan. This Ordinance will not allow BESS facilities to be in any new zoning districts where they were not previously allowed. This Ordinance also incorporates BESS-specific standards to ensure the protection of public health, public safety, natural resources and the environment from the unique and complex risks these facilities pose.
PUBLIC HEARING NOTICE:
In accordance with State Law and Solano County Zoning Regulations, notice of a public hearing was published at least 20 days before the scheduled hearing in the local newspapers.
ALTERNATIVES:
1. Implement more restrictive standards than currently proposed. This may provide enhanced safety measures but might result in applicants bypassing the local process to submit for and ultimately receive their permits directly from the California Energy Commission (CEC), resulting in a loss of local control.
2. Request additional stakeholder consultation. This may provide additional public input but would extend the timeline for ordinance completion. Staff has engaged with stakeholders throughout the moratorium and has considered this feedback in the formation of the current proposed ordinance language. For regulations of BESS to come into effect prior to the interim moratorium expiration on Jan 23, 2026, an ordinance regulating BESS must be adopted prior to December 23, 2025.
OTHER AGENCY INVOLVEMENT:
County Counsel, the Solano County Sheriff’s Office/Office of Emergency Services, the Solano County Agricultural Commissioner’s Office and the County Administrator’s Office have been involved in the process of developing the proposed ordinance language.
CAO RECOMMENDATION:
APPROVE DEPARTMENTAL RECOMMENDATION