California Title 24 is the state’s building energy efficiency standards, updated every three years by the California Energy Commission (CEC). Part 6 of Title 24 is the building energy standard that, since the 2020 edition, mandates solar photovoltaic systems on virtually all new low-rise residential construction in California. The 2022 Title 24 edition expanded this to include new non-residential buildings and most additions.
For solar installers in California, Title 24 intersects with permit work in three specific ways: Title 24 compliance documentation must often accompany solar permit packages on new construction; Title 24 sets the minimum solar system size for new construction (the mandatory minimum determined by energy modeling); and Title 24’s battery storage credits incentivize paired solar-plus-storage installations in ways that affect system design decisions for new builds.
Understanding exactly what Title 24 requires — and what it does not — prevents two common installer errors: over-designing systems to comply with imagined Title 24 requirements on retrofit projects, and under-documenting new construction solar packages that actually need Title 24 compliance forms in the permit set.
Direct answer. California Title 24 Part 6 (2022 edition) mandates solar PV on new low-rise residential construction (≤ 3 stories) and on new non-residential buildings ≥ 10,000 square feet. The mandatory minimum solar system size for new residential is determined by a formula based on conditioned floor area and climate zone. Title 24 does NOT apply to solar retrofits on existing buildings — only new construction and most substantial additions. The Title 24 compliance documentation (CF1R energy report or comparable) must be included in the permit package for all new construction solar installations.
California Title 24 — What It Is and What It Covers
California Title 24 consists of multiple parts:
- Part 1: Administrative regulations
- Part 2: California Building Code (CBC) — structural and architectural
- Part 3: California Electrical Code (CEC) — NEC 2020 with CA amendments
- Part 4: California Mechanical Code
- Part 5: California Plumbing Code
- Part 6: California Energy Code — the building energy efficiency standard
Part 6 (Energy Code) is the Title 24 provision that governs solar PV mandates. It is updated every 3 years; the 2022 edition (effective January 1, 2023) is the current version as of 2026.
Title 24 Part 6 applies to:
- New low-rise residential construction (single-family and multi-family up to 3 stories) — mandatory solar since 2020
- New non-residential buildings — mandatory solar under 2022 edition for buildings ≥ 10,000 sq ft
- Substantial additions and alterations — additions that trigger a Title 24 compliance review may also require solar
Title 24 Part 6 does NOT apply to:
- Solar retrofits on existing buildings — adding solar to an existing home or building does not trigger Title 24 compliance requirements for the solar permit
- Minor alterations that do not meet the “substantial” threshold
Retrofit vs. new construction. The most common installer misunderstanding of Title 24 is applying it to retrofit solar projects. If a homeowner is adding solar to their existing home built in 2010, Title 24 solar compliance documentation is NOT required in the permit package — this is a standard AHJ permit for an alteration, governed by the California Electrical Code and structural code, not Title 24 energy compliance. Title 24 applies when the solar installation is part of new building construction or a substantial addition that triggers a new energy compliance review.
Title 24 Mandatory Minimum Solar System Size — New Residential
For new low-rise residential construction, Title 24 Part 6 (2022 edition) specifies a mandatory minimum PV system size calculated as:
Minimum solar (kW DC) = (CFA × 0.572 + 1.2 × Nbr) × CZ_factor ÷ 1000
Where:
- CFA = Conditioned Floor Area of the dwelling (square feet)
- Nbr = Number of bedrooms
- CZ_factor = Climate zone adjustment factor (varies by California climate zone; ranges approximately 1.0 in coastal zones to 1.4 in hot inland zones)
Example calculation for a new 3-bedroom, 2,000 sq ft home in climate zone 12 (Sacramento):
- CZ_factor for CZ12: approximately 1.15
- Minimum = (2,000 × 0.572 + 1.2 × 3) × 1.15 ÷ 1000
- Minimum = (1,144 + 3.6) × 1.15 ÷ 1000
- Minimum = 1,147.6 × 1.15 ÷ 1000
- Minimum ≈ 1.32 kW DC
Note: This minimum is the regulatory floor — most energy modeling on 2,000+ sq ft homes results in higher minimum requirements. The actual minimum for permit compliance is determined by the project’s Title 24 energy model, not this simplified formula.
Title 24 Battery Storage Credit
The 2022 Title 24 edition introduced a battery storage credit that allows homebuilders to reduce the required PV system size when the system includes battery storage:
Battery credit: If the solar system is paired with a battery storage system meeting minimum specifications (4 kWh usable capacity minimum for residential), the mandatory minimum PV system size is reduced by up to 25%.
Design implication: For production-home builders installing solar on all new units, the battery credit can meaningfully reduce per-unit solar cost by allowing a smaller PV system when storage is included. For solar installers working with builders, understanding this credit is relevant to the system design discussion — the optimal configuration from a Title 24 compliance standpoint may not be a standalone solar system.
What California Title 24 Documentation Goes in the Solar Permit Package
For new construction solar (where Title 24 applies), the solar permit package must include Title 24 compliance documentation that confirms the installed PV system meets the Title 24 minimum requirements.
Required Title 24 documentation for new construction solar permits:
| Document | Description | Who Prepares It |
|---|---|---|
| CF1R (Certificate of Compliance) | Energy compliance form generated by an approved Title 24 energy analysis software (EnergyPro, CBECC-Res) | Title 24 energy analyst / HERS rater |
| PV system worksheet | Shows the PV system specifications in the energy model | Title 24 energy analyst |
| Equipment compliance verification | Confirms the installed PV system matches the CF1R specification | Installation contractor; verified by HERS rater at inspection |
| CF2R (Installation Certificate) | Signed by the installer confirming the system was installed per the CF1R | Solar installer |
| CF3R (Verification Certificate) | Signed by HERS rater confirming inspection of the installed system | HERS rater (field inspection) |
HERS (Home Energy Rating System) rater: California’s Title 24 compliance requires a HERS-certified rater to verify installation for certain high-performance features. PV systems on new construction are typically a HERS verification item — the rater confirms the installed system matches the permit documentation.
Watch out — HERS rater coordination. Solar installers on new construction projects sometimes install systems that match the AHJ permit approval but do not match the CF1R specification (different module count, different inverter model, different tilt). If the installed system does not match the CF1R, the HERS rater cannot issue the CF3R, and the building cannot receive its certificate of occupancy. Coordinate with the builder's Title 24 energy analyst before any substitution that changes the solar system parameters from the CF1R.
California Title 24 Solar Compliance Checklist
For New Residential Construction:
- Confirm Title 24 compliance triggers — New construction or qualifying substantial addition. Retrofit = no Title 24 solar requirement.
- Obtain CF1R from energy analyst — The CF1R specifies the minimum PV system and any battery storage credit applied.
- Verify installed system meets CF1R — Module count, wattage, inverter, and tilt/orientation must match CF1R within allowed tolerances.
- Include CF1R in permit package — The AHJ permit package for new construction solar must include the CF1R documentation.
- Coordinate HERS rater before installation — Schedule HERS rater field inspection as part of the solar installation inspection process.
- Complete CF2R (Installation Certificate) — Sign and provide to HERS rater before the CF3R inspection.
- HERS rater issues CF3R — CF3R is required for certificate of occupancy issuance.
For Retrofit Solar (Existing Buildings):
- Confirm no Title 24 trigger — Retrofits on existing buildings generally do NOT require Title 24 solar compliance documentation.
- Standard CEC (NEC 2020 with CA amendments) permit — File through SolarApp+ if eligible; full plan check if not.
- No CF1R required — The AHJ permit package is the standard solar permit package without Title 24 energy compliance forms.
California Climate Zones and Solar Performance
California’s 16 climate zones (as defined by Title 24) significantly affect solar system performance and therefore the Title 24 minimum solar size calculation. The climate zone factor in the minimum PV formula is highest in inland desert and Central Valley areas where cooling loads are highest:
| Climate Zone | Representative Area | Approximate CZ Factor | Solar Irradiance (GHI) |
|---|---|---|---|
| CZ 1 (Northwest CA) | Arcata, Eureka | Low (~0.85) | ~4.2 kWh/m²/day |
| CZ 3 (Coastal Bay Area) | San Jose, Oakland | Low (~0.90) | ~4.7 kWh/m²/day |
| CZ 6 (Los Angeles) | LA Basin | Moderate (~1.00) | ~5.2 kWh/m²/day |
| CZ 9 (LA inland) | Pasadena, Burbank | Moderate (~1.05) | ~5.5 kWh/m²/day |
| CZ 12 (Sacramento) | Sacramento Valley | High (~1.15) | ~5.5 kWh/m²/day |
| CZ 16 (High Desert) | Lancaster, Palmdale | High (~1.30) | ~6.2 kWh/m²/day |
California Title 24 Solar and NEM 3.0 — Combined Compliance Challenge
California’s NEM 3.0 (net energy metering 3.0), which took effect for new applications in 2023, significantly reduced the value of solar exports for IOU customers (PG&E, SCE, SDG&E). NEM 3.0 created a financial incentive to pair solar with battery storage to maximize self-consumption rather than export — which aligns with Title 24’s battery storage credit direction.
How NEM 3.0 interacts with Title 24 solar design:
- Under NEM 3.0, export compensation is based on the “avoided cost calculator” rate — typically $0.04–0.08/kWh vs. the $0.25–0.35/kWh retail rate
- This export rate reduction makes oversizing solar (for maximum export) less valuable than under NEM 2.0
- Title 24’s battery credit and NEM 3.0’s economics together push new construction solar design toward right-sized solar + battery combinations
For AHJ-specific California permit requirements, see California AHJ Solar Permit Guide and LADBS SolarApp+ Guide.
According to the California Energy Commission (CEC), the 2022 Title 24 standards are projected to reduce residential energy use by approximately 3% compared to the 2019 standards. The SEIA California solar market data shows that Title 24 solar mandates have contributed significantly to California’s new construction solar volume since 2020. According to NREL’s 2024 permitting report, California’s SolarApp+ adoption alongside Title 24 mandates creates one of the most systematized solar deployment environments in the US.
Common Title 24 Solar Compliance Mistakes
| Mistake | Description | Fix |
|---|---|---|
| Applying Title 24 to retrofit projects | Adding Title 24 documentation to a retrofit solar permit unnecessarily | Confirm project type; Title 24 only applies to new construction |
| Wrong CF1R in permit package | Including an old or preliminary CF1R; final CF1R not updated to match installed system | Get the final CF1R from the energy analyst before permit submission; verify parameters match |
| HERS rater not scheduled | No HERS rater engaged before installation | Coordinate HERS rater with the builder’s Title 24 process from project start |
| System installed differs from CF1R | Different module count, model, or inverter than CF1R specifies | Match CF1R exactly; any substitution requires CF1R revision by energy analyst |
| CF2R not signed | Installer did not complete the Installation Certificate | Complete CF2R before HERS inspection; unsigned CF2R blocks CF3R |
Title 24 Solar Performance Benchmarks
2020
Year solar mandate began for new CA residential construction
California Title 24 2019 edition, effective January 2020
25%
Maximum PV size reduction with battery storage credit
CEC Title 24 2022 edition
16
California climate zones affecting minimum solar size calculation
CEC Title 24 climate zone map
96.2%
Heaven Designs first-pass approval — all CA AHJs
Heaven Designs internal, Q1 2026
How Heaven Designs Supports California New Construction Solar
Title 24 new construction solar requires coordination between the energy analyst (CF1R), the solar permit designer, and the HERS rater — three separate parties whose documentation must align exactly. Heaven Designs’ California permit workflow integrates this coordination.
- Solar Permit Design (USA) — California new construction and retrofit solar permits. Title 24 CF1R documentation integration for new construction. SolarApp+-optimized for retrofit. 96.2% first-pass approval rate across CA AHJs.
- Solar 3D Pre-Design — 48-hour pre-design confirming system size against Title 24 CF1R parameters before the permit package is prepared.
- California AHJ Solar Permit Guide — AHJ matrix for LADBS, San Diego DSD, Riverside County, and other CA markets.
- Download sample deliverables — Sample new construction California solar permit package including CF1R integration.
Glossary: AHJ, NEC 705, SolarApp+.
FAQ
Does Title 24 apply to all California solar projects?
No. California Title 24 Part 6 solar mandates apply only to new construction and qualifying substantial additions. Adding solar to an existing residential or commercial building (a retrofit) does NOT trigger Title 24 solar compliance requirements. Retrofit solar on existing buildings is permitted under the California Electrical Code (NEC 2020 with California amendments) through the standard AHJ permit process, with no Title 24 energy compliance documentation required.
What is a HERS rater and why do I need one for Title 24 solar?
A HERS (Home Energy Rating System) rater is a certified professional who performs field verification of energy-efficiency installations in California new construction. For Title 24 solar compliance, the HERS rater verifies that the installed PV system matches the CF1R specification and issues the CF3R (Verification Certificate). Without the CF3R, the building cannot receive a certificate of occupancy in California. HERS raters are certified by CHEERS, CalCERTS, or other CEC-approved certification bodies.
How does the Title 24 battery storage credit work?
The 2022 Title 24 battery storage credit allows homebuilders to reduce the mandatory minimum PV system size by up to 25% when the system is paired with a battery storage system with at least 4 kWh usable capacity. The credit is applied in the Title 24 energy model by the energy analyst when preparing the CF1R. The battery system must be installed and verified to claim the credit — a permit that includes the battery credit in the CF1R but installs solar without storage would not satisfy Title 24 compliance.
What software is used for California Title 24 solar compliance?
The most widely used Title 24 energy compliance software for residential projects is EnergyPro (by EnergySoft) and CBECC-Res (developed by the California Energy Commission). These software packages perform the Title 24 energy analysis, calculate the mandatory minimum PV system size, and generate the CF1R compliance documentation. Energy analysts (not solar installers) typically use this software — solar installers work with the CF1R output to design the system and include the CF1R in the permit package.
Can I substitute a different inverter or module than what’s on the CF1R?
Yes, but you must coordinate with the energy analyst. If you need to substitute a different module (different wattage, different manufacturer) or a different inverter, the energy analyst must update the CF1R to reflect the substitution and re-issue the CF1R before the HERS rater’s inspection. Installing a different product than what the CF1R specifies without updating the CF1R will fail the HERS verification, blocking the certificate of occupancy. Always get a revised CF1R before making any substitution that changes system parameters.
