California's Title 24 Solar and Battery Storage Mandate on New Multifamily Buildings

Published August 10, 2026

California's Title 24 Energy Code requires a solar PV system on virtually all newly constructed buildings, including multifamily. High-rise multifamily also faces a prescriptive battery storage requirement. Existing buildings are not retrofitted.

The short answer

Yes. Since the 2022 Title 24 Part 6 Energy Code took effect January 1, 2023, a solar photovoltaic system has been prescriptively required on virtually all newly constructed buildings in California, including multifamily. High-rise multifamily buildings also face a prescriptive battery storage requirement. The mandate applies to new construction, not to buildings you already own.

Last verified: August 10, 2026

Where this lives and when it applies

Title 24 Part 6 is California's Building Energy Efficiency Standards, commonly called the Energy Code. It is administered by the California Energy Commission and updated on the same triennial cycle as CALGreen and the rest of Title 24.

The 2022 Energy Code took effect January 1, 2023, and is the edition currently governing most active permits. The 2025 Energy Code, part of the 2025 California Building Standards Code, was published July 1, 2025, and takes effect for buildings with permit applications submitted on or after January 1, 2026, according to the California Energy Commission and the Department of General Services. The Energy Commission describes the 2025 edition as expanding heat pump use and electric readiness in newly constructed residential buildings.

As with CALGreen, the code edition that governs a given project is generally the one in force when the permit application is submitted, not when construction wraps. Confirm the applicable edition with your city's building department before assuming which rule set governs your project.

The solar PV mandate, in plain terms

California's solar mandate did not start with multifamily. It began with the 2019 Energy Code, effective January 1, 2020, requiring solar PV on new single family homes and low-rise multifamily buildings up to three stories. The 2022 Energy Code broadened that base further. Per the California Energy Commission's own Energy Code Support Center, a solar PV system is now prescriptively required for all newly constructed buildings, a category that reaches both low-rise and high-rise multifamily, not just single family homes and small apartment buildings.

"Prescriptively required" means solar is the default path to code compliance. Some flexibility exists through the code's performance compliance pathway, where a designer can trade off building elements against each other, but the baseline expectation for a new multifamily project is that it carries solar.

The battery storage requirement, and where it narrows

Battery storage is where the requirement gets more specific to building type. According to the Energy Commission, battery energy storage systems are prescriptively required for newly constructed nonresidential buildings and high-rise multifamily buildings. That is a narrower category than the solar mandate.

| Building type | Solar PV | Battery storage |

|---|---|---|

| Single family, new construction | Required | Battery ready wiring; installed battery not mandatory |

| Low-rise multifamily (roughly 3 stories or fewer), new construction | Required | Requirement scope not fully confirmed here; consult a title 24 consultant |

| High-rise multifamily, new construction | Required | Prescriptively required |

| Nonresidential, new construction | Required | Prescriptively required |

Treat the low-rise multifamily battery row as an open question rather than a settled fact. The sources reviewed for this article were clear that single family homes get a battery ready standard rather than a mandatory installed battery, and clear that high-rise multifamily gets a mandatory installed battery, but did not resolve where a typical South Bay low-rise apartment building, the three-story fourplex or twelve-unit walkup common in Torrance or Gardena, lands between those two poles. If you are developing or substantially renovating a low-rise multifamily project, get that answer in writing from your title 24 consultant before you finalize the electrical and mechanical design.

What this means for a South Bay owner or developer

If you are building new multifamily anywhere in the South Bay, whether a small infill fourplex in Hawthorne or a larger project in Torrance, budget for solar PV from the start. It is not an optional green feature at this point, it is the default compliance path the Energy Code assumes you will take.

If your project is high-rise multifamily, budget for battery storage as well, since the Energy Commission describes that requirement as prescriptive rather than optional for that building category.

If you already own an existing multifamily building, this mandate does not reach back and require you to install solar or batteries. It is a new-construction standard. The mandate becomes relevant to an existing owner mainly at the point of a major addition, substantial rehabilitation, or new construction on the same site, when the project may trigger full Energy Code compliance for the new work.

If you are buying a recently permitted multifamily property, ask for the Title 24 compliance documents from the approved plan set. That tells you definitively what solar and battery capacity is actually installed, rather than relying on a rooftop walkthrough.

FAQ

Do I have to add solar panels to my existing apartment building?

No. The Title 24 solar mandate applies to new construction. It does not require retrofit installation on a building that was already built before the requirement applied to it.

Does the solar requirement apply to small buildings, like a fourplex?

Yes. The requirement reached low-rise multifamily starting with the 2019 Energy Code and was broadened further in the 2022 Energy Code, which the Energy Commission describes as covering all newly constructed buildings, not just larger projects.

Is battery storage required on every new apartment building?

Not confirmed as a blanket rule. It is clearly prescriptive for high-rise multifamily. Whether a smaller low-rise multifamily project faces a mandatory installed battery or only battery ready wiring was not something this article could confirm from a primary source. Confirm with a title 24 consultant for your specific project.

When does the 2025 Energy Code start applying?

For buildings with permit applications submitted on or after January 1, 2026, according to the California Energy Commission.

Can I use a performance compliance path to avoid installing solar?

The Energy Code offers a performance pathway that allows tradeoffs among building features, but the Energy Commission describes solar PV as prescriptively required for new construction generally. Whether a specific project can achieve compliance through tradeoffs instead of installed solar is a technical determination for a title 24 energy consultant, not a general rule this article can state.

Does this mandate affect my property taxes or insurance?

This article did not research property tax or insurance effects of adding solar or battery systems and makes no claim about them. Confirm with your tax preparer and insurance carrier separately.

This article is general information about a state energy code and is not a substitute for a licensed title 24 energy consultant, architect, or engineer. Confirm the applicable code edition, solar sizing, and battery storage requirements for your specific project with a qualified professional and your local building department before you design, permit, or budget a project.

Topics: compliance, solar, Title 24, multifamily, South Bay, property management

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