Battery Energy Storage for New Construction
The battery needs a home before the walls close.
Most new nonresidential buildings and every high-rise multifamily building that requires PV also requires battery storage. We size it to the Energy Code, site it to the fire code, and design it so it can serve resilience and demand management as well as compliance.
What the Code Requires
Required on most new commercial buildings and all high-rise multifamily.
Under Section 140.10(b), newly constructed nonresidential buildings required to install PV must also install a battery energy storage system sized to the PV system, with limited exceptions. Under Section 170.2(h), multifamily buildings of four or more habitable stories required to install PV must do the same. Capacity is calculated from the PV size using building-type energy and power factors; the 2025 Energy Code updated the equations and factors for all building types.
Batteries must be certified under Joint Appendix JA12, which sets requirements for safety, minimum performance, and controls, including usable capacity above 5 kWh, round-trip efficiency above 80% for prescriptive compliance, and retained capacity of 70% after 4,000 cycles or under a 10-year warranty.
- Sized to the PV system using the Energy Code's capacity factors, coordinated with the energy consultant.
- Located to the fire code with clearances, separation, ventilation or thermal management, signage, and emergency shutoff reviewed by the fire authority.
- Documented in the Certificate of Compliance and the Certificate of Installation that the building department reviews before final.
| Building | Battery |
|---|---|
| Nonresidential, listed occupancy | Required when PV is required; exceptions for small systems and several occupancies in Climate Zone 1 under the 2025 code |
| Multifamily, 4+ stories | Required when PV is required; exempt if PV is under 15% of the calculated size or the battery would be under 10 kWh |
| Multifamily, 1 to 3 stories | Optional; a 7.5 kWh JA12 battery reduces required PV by 25% |
| Single-family | Optional; reduces required PV |
Summary of published California Energy Commission materials. Exceptions apply; requirements depend on building type, climate zone, and permit timing.
Beyond Compliance
A compliance battery can be a resilience battery.
The code sets a minimum capacity. The owner decides what else the system does, and the decision is cheapest during electrical design.
Backup for critical loads
A critical-load panel, transfer equipment, and controls let the battery carry life-safety systems, elevators, refrigeration, communications, or community spaces through outages and public safety power shutoffs.
Demand charge management
Demand charges are often the largest line on a commercial bill. Storage sized to the load profile clips peaks from HVAC, refrigeration, process equipment, and EV charging.
Time-of-use optimization
Under the net billing tariff and time-varying rates, shifting solar production into evening peaks increases the value of every kilowatt-hour the roof produces.
The Design Problem
Where the battery goes is decided on paper or negotiated in the field.
A code-compliant battery location needs clearances from exits, windows, and other equipment, separation from occupied spaces where required, ventilation or thermal management appropriate to the chemistry, signage, and access for the fire department. Lead times on battery systems and the switchgear they connect to can exceed what remains of the construction schedule if ordered late. Electrical and fire inspections of the battery must close before the building's final.
We fix the location in design development with the fire authority's requirements in hand, schedule procurement with the equipment submittals, and sequence inspections ahead of the Certificate of Occupancy.
How we sequence itQuestions
Frequently Asked Questions
Which new buildings in California must install a battery?
Newly constructed nonresidential buildings required to install PV under Section 140.10 must also install battery storage, with limited exceptions, and multifamily buildings of four or more habitable stories required to install PV must install a battery under Section 170.2(h). Low-rise multifamily and single-family homes are not required to include storage.
How is the required battery sized?
From the PV system size, using building-type energy and power capacity factors from the Energy Code tables, adjusted for round-trip efficiency. The 2025 Energy Code updated the equations and the factors for all building types.
What does JA12 certification mean?
Joint Appendix JA12 is the Energy Code's qualification standard for battery storage systems, covering safety, minimum performance, and control strategies. Batteries used for compliance must be certified to the Energy Commission under JA12.
Where can the battery be installed?
In a location that meets the fire code and the fire authority's requirements for clearances, separation, ventilation or thermal management, signage, and emergency access. The location should be fixed during design development, not found during construction.
Can the required battery also provide backup power?
Yes, when the critical-load panel, transfer equipment, and controls are designed for it. The code sets a minimum capacity; many owners size beyond it for resilience or demand charge management.
Discuss Your Project
Size the battery to the code and the building.
Send us the drawings and we will calculate the required capacity, propose a location the fire authority will accept, and show what the system can do beyond compliance.