Does Title 24 require solar on my new building?
For new nonresidential and multifamily construction in California, generally yes — and for most of those buildings, battery storage as well. The 2025 code took effect in January 2026.
Short answer
Yes, for most new construction. California’s 2025 Title 24 Part 6 Energy Code, effective January 1, 2026, requires photovoltaic systems on new nonresidential and multifamily buildings, and battery storage for most nonresidential and high-rise multifamily projects. Low-rise multifamily buildings up to three storeys must install PV sized by either a conditioned-floor-area or solar-access-roof-area method, whichever is smaller, and may install battery storage optionally to reduce the PV requirement. High-rise multifamily is treated as nonresidential. Required capacity varies by building type and climate zone. This is a code obligation, not an incentive, and compliance is demonstrated at permit.
On this page
What Title 24 Part 6 is
Title 24, Part 6 of the California Code of Regulations is the state’s Building Energy Efficiency Standards — the Energy Code. It is updated on a roughly three-year cycle, and the 2025 edition took effect on January 1, 2026.
It is not an incentive. It is an obligation, and it applies at permit.
Solar and storage requirements for new construction
| Building type | Photovoltaic | Battery storage |
|---|---|---|
| Nonresidential | Required, sized by building type and climate zone | Required for most project types |
| High-rise multifamily (4+ storeys) | Treated as nonresidential | Required, as nonresidential |
| Low-rise multifamily (up to 3 storeys) | Required, sized by conditioned floor area or solar-access roof area | Optional — installing storage reduces the PV requirement |
Required PV capacity generally follows the smaller of a conditioned-floor-area calculation and a solar-access-roof-area calculation. Capacity factors vary considerably by occupancy — a restaurant in a high-sun climate zone carries a far higher requirement per square foot than a warehouse or a library.
What else the 2025 code pushes
Beyond PV and storage, the current cycle continues a clear direction: deeper electrification, more efficient heat-pump technology for space and water heating, electric-ready infrastructure so future conversion is not a retrofit, and stronger ventilation standards.
For a developer this matters at design stage rather than at construction, because electric-ready provisions are cheap to build in and expensive to add later.
Compliance as a design decision, not a checkbox
The common mistake is treating the PV requirement as a line item to be minimised, which produces a compliance-sized array bolted on late with no thought to future expansion, storage integration or EV charging load.
Designed properly at the same time, the same building can carry a system that satisfies code, handles the charging infrastructure residents or tenants will demand, and leaves room to grow. The incremental cost of doing it once is far lower than the cost of doing it twice.
See multifamily solar and commercial solar.
Sources and further reading
- California Energy Commission — Building Energy Efficiency Standards
- Frame Energy — California Title 24 Part 6 explained for multifamily and commercial developers
Questions we get asked
Does Title 24 apply to my existing building?
The photovoltaic and battery requirements described here apply to new construction. Existing buildings encounter Title 24 through alterations and additions, where requirements are triggered by the scope of work rather than applied wholesale. A major re-roof or a significant electrical alteration can bring code requirements into play.
Can I trade off the solar requirement?
The code offers prescriptive and performance compliance paths, and there are defined trade-offs — for example, low-rise multifamily projects can reduce the PV requirement by installing battery storage. Which path is cheapest depends on the project, and it is worth modelling both rather than defaulting to prescriptive.
How is the required PV size calculated?
Sizing generally follows the smaller of two methods: a conditioned-floor-area calculation and a solar-access-roof-area calculation, with capacity factors varying by building type and climate zone. That is why a restaurant and a warehouse of identical footprint have very different requirements.
Is battery storage mandatory?
For most new nonresidential and high-rise multifamily projects under the current code, battery storage is required. Low-rise multifamily can install storage optionally to reduce the PV requirement. Confirm the specific requirement for your building type, climate zone and compliance path.
Who signs off compliance?
Compliance documentation is submitted to the local authority having jurisdiction as part of permitting, using the forms for your building type and chosen path. Getting this wrong is a plan-check delay rather than a disaster, but it is an avoidable one.
Reviewed and updated August 21, 2026
Bring us in at design stage, not at plan check.
Code-compliant PV designed alongside the storage and charging infrastructure the building will actually need costs far less than three separate projects.