Introduction
California made history with its 2022 Building Energy Efficiency Standards by significantly expanding solar photovoltaic (PV) requirements and introducing battery energy storage system (BESS) mandates for certain building types. If you're building in California, understanding what the solar and battery mandates require — and how they're verified — is essential to getting your project to permit final.
What the 2022 Title 24 Standards Require
Under the 2022 Title 24 standards (effective January 1, 2023), all new single-family homes and low-rise multifamily buildings (three stories or fewer) are required to include a solar PV system. This requirement was first introduced under the 2019 standards for single-family homes.
The 2022 standards significantly expanded the solar mandate to nonresidential buildings. New commercial buildings including offices, retail stores, schools, grocery stores, warehouses, and high-rise multifamily buildings (four stories and above) must now include solar PV systems sized according to the building's conditioned floor area.
Battery Storage Requirements
Battery energy storage systems (BESS) are prescriptively required for newly constructed nonresidential and high-rise multifamily buildings under the 2022 standards.
For new single-family homes and low-rise multifamily buildings, BESS is not mandatory — but BESS-ready infrastructure is. This means the home must be built with the electrical panel capacity, dedicated space, and wiring infrastructure to support a future battery installation. Installing a qualifying battery system (minimum 7.5 kWh usable capacity, JA12-compliant) allows the required PV system size to be reduced by up to 25%, which incentivizes battery installation even though it's not required.
How Solar System Size Is Determined
For residential buildings, the required solar PV system size is calculated based on conditioned floor area, climate zone, and the building's energy consumption. The energy consultant (ECC writer) performs this calculation using CEC-approved compliance software and specifies the required system on the CF1R.
For nonresidential buildings, the PV system size is based on conditioned floor area with specific minimum watts-per-square-foot requirements that vary by building type and climate zone.
Exemptions and Alternative Compliance
There are limited exemptions to the solar requirement. Buildings where the roof area is insufficient to accommodate the minimum required system may qualify for a reduction or exemption. Shading from adjacent trees or structures that would reduce system output below a threshold can also reduce the required size.
Buildings that connect to a community solar program (a shared solar facility) may be able to satisfy the requirement through that alternative, subject to CEC approval.
These exemptions and alternatives must be documented and calculated by the energy consultant — they are not automatic.
HERS Verification of Solar and Battery Systems
Like other Title 24 compliance measures, solar PV and battery storage systems must be field-verified. A HERS Rater is required to confirm that the installed system matches the specifications on the CF1R, including verifying the inverter, panel count, system capacity, and battery storage usable capacity.
The HERS Rater will check the equipment model numbers against what was specified in the compliance documentation, confirm the system is operational, and submit verification data to the HERS registry to generate the CF3R.
This verification must be completed before permit final. Scheduling your HERS Rater to verify the solar and battery system at the same time as other HERS measures (duct leakage, HVAC verification, etc.) is the most efficient approach.
What This Means for Builders
Solar PV and battery storage are now baseline requirements for virtually all new residential construction in California. They should be incorporated into the project design from the beginning — not treated as add-ons.
Work with your energy consultant early to determine the correct system size for your project, confirm the solar PV contractor understands the CF1R specifications, ensure the battery storage system meets the minimum usable capacity requirement, and schedule your HERS Rater to verify both systems before permit final.
Conclusion
California's 2022 Title 24 standards require solar PV on most new construction, battery storage on nonresidential and high-rise multifamily buildings, and battery-ready infrastructure on single-family homes. The requirements are determined by the energy consultant, documented on the CF1R, and verified in the field by a HERS Rater. Building these requirements into your project plan from the start is the most cost-effective approach.