01Key facts / TL;DR
Yes, newly constructed single-family buildings generally need PV under §150.1(c)14, subject to the actual documented exceptions.
No, a qualifying PV exception does not mean every readiness, electrical or other code requirement disappears.
Yes, the cited battery option can reduce Equation 150.1-C PV size by 25% with JA12 compliance and at least 7.5 kWh compliance cycling capacity.
It depends on the project: BESS-ready infrastructure under §150.0(s) is distinct from a mandate to install a battery.
02Keep four questions separate
First ask whether the project is subject to new-building PV requirements. Second calculate the applicable PV size and evaluate supported exceptions. Third determine whether an installed battery is part of the compliance approach. Fourth check the mandatory infrastructure/readiness requirements that apply to this building.
These questions are related but not interchangeable. A homeowner can need BESS-ready infrastructure without choosing to install a battery. A qualifying battery can affect a PV calculation without eliminating PV altogether. A standalone storage electrical permit is not automatically a new-house CF1R modeling task.
This guide addresses the cited single-family framework. Multifamily and nonresidential PV/storage requirements have different provisions and should not be inferred from this page. Confirm building classification, application date and the actual project scope before selecting software or claiming an exception.
03PV sizing starts with the CEC method, not a guessed panel count
The CEC single-family solar FAQs describe the minimum as the smaller of the qualifying solar access roof area calculation and Equation 150.1-C. The equation uses climate zone, conditioned floor area and dwelling units. A module count without module capacity or supported site information does not establish the required kWdc.
Solar access roof area, or SARA, is not simply the building footprint. The CEC describes qualifying roof and other support areas, shading and exclusions. Its current FAQ gives SARA multipliers of 18 watts per square foot for steep-sloped roofs and 14 watts per square foot for low-sloped roofs. Have the responsible designer document the applicable area and conditions.
The FAQ explains that electric heat-pump loads do not simply get added to the prescriptive minimum as a retail energy-use estimate. Do not substitute a utility bill offset or a salesperson’s recommended array for the Energy Code calculation. A larger voluntary system can still have separate design, interconnection and installation considerations.
04Exceptions need evidence and their full conditions
The CEC describes limited SARA, a calculated minimum below 1.8 kWdc, an enforcement-authority snow-load determination and pre-January 1, 2020 planning conditions among the provisions affecting PV. These are not interchangeable checkboxes that an applicant can select without supporting facts.
For the less-than-80-contiguous-square-foot SARA provision, Chapter 7 discusses individual roof areas and the treatment of steep-slope northerly orientations. Do not turn one small roof plane into an automatic whole-project exemption. The designer must assess the applicable roof areas and all conditions using the adopted text and current guidance.
The snow-load provision requires the enforcement authority’s determination about the referenced structural standard; “it sometimes snows here” is insufficient. Likewise, a building’s age or an old concept drawing does not establish the specific pre-2020 planning-approval conditions. Send the actual record if a provision is claimed.
The CEC explicitly warns against combining exceptions as a shortcut. In particular, the battery-related reduction cannot be combined with the under-1.8-kWdc exception to avoid both systems. Read the FAQ and document the selected approach rather than stacking favorable fragments.
05The 25% battery option is not any battery with a large label
The cited option permits Equation 150.1-C PV size to be reduced by 25% when installed with a qualifying BESS. The battery must meet Joint Appendix JA12 and have at least 7.5 kWh compliance cycling capacity. That is not necessarily the product’s advertised total or nominal capacity.
Chapter 7 explains that usable capacity and any commissioned reserve affect capacity available for daily compliance cycling. Ask for the supported product and commissioning information. A battery reserved entirely for emergency backup should not be assumed to deliver the same compliance contribution as a qualified cycling configuration.
The selected PV and battery must actually be included in the coordinated permit and installation scope. A note saying “future battery” is not an installed JA12 system for this reduction. Do not remove required PV from the report because an owner is considering storage later.
CEC Chapter 7: capacity and the battery reductionJA12 qualification requirements
06BESS-ready is a separate mandatory infrastructure question
For 2025, Chapter 7 identifies §150.0(s) readiness for newly constructed single-family buildings with one or two dwelling units and electrical service greater than 125 amps. The readiness requirement does not apply if a BESS is installed under the applicable provision. This is not a universal battery purchase mandate.
Have the qualified electrical designer identify the service rating and required infrastructure under the actual section. A readiness note in an energy report does not replace the electrical design or establish that a panel can safely accept a particular storage system. Exactly 125 amps should not be rewritten as “greater than 125.”
Solar-ready rules are another distinct subject with their own applicability. The CEC solar FAQ specifically limits the cited single-family subdivision solar-ready provisions and discusses ADUs on existing lots. Do not assume every PV exception automatically invokes the same solar-ready package.
07New homes, ADUs and existing-building work
The CEC says the new-building PV provisions do not apply to additions or alterations to existing buildings or unconditioned buildings. The BESS-ready framework discussed here is likewise a newly constructed single-family requirement. That does not exempt electrical work, equipment or other applicable code provisions on an existing property.
A newly constructed detached ADU is not the same scope as an addition or conversion. The CEC solar FAQ says an existing PV system alone does not satisfy a new ADU’s PV requirement, while qualifying newly added modules may be incorporated into an existing system under the documented conditions. Metering and load-serving-entity approval remain separate considerations.
Supply main-house and ADU relationships, service information and any proposed shared PV arrangement. Do not infer a readiness exception from small floor area alone or assume every garage conversion is detached new construction. Classification and documented scope come first.
ADU energy-compliance guideNew-construction modeling service
08Illustrative sizing discussion—not a completed compliance run
ILLUSTRATIVE ONLY: suppose the applicable Equation 150.1-C result for a proposed home is 4.0 kWdc before the qualifying battery reduction. If the project properly uses that option, 25% of 4.0 is 1.0, leaving 3.0 kWdc under that calculation. This arithmetic does not establish the project’s final requirement, SARA result or compliance.
The team still confirms JA12 qualification, at least 7.5 kWh compliance cycling capacity, actual installation and all applicable conditions. It does not subtract another exception to declare zero PV. The electrical designer separately checks BESS-ready or installed-system requirements.
For intake, send the roof plan, supported shading/SARA evidence, conditioned area and units, PV/battery schedules, service rating and claimed exception documents. Mark preliminary equipment as provisional. Final energy documents, drawings and installed-system records must describe the same coordinated choice.
09Six PV and battery-readiness questions
Does every new home have to buy a battery?
No. BESS installation and BESS-ready infrastructure are different questions. The cited 2025 readiness provision has specific new-single-family, unit-count and service-rating applicability.
Can any 7.5-kWh battery reduce required PV?
No. The option requires JA12 compliance and at least 7.5 kWh compliance cycling capacity, not just an advertised nominal rating. Confirm the equipment, configuration and actual installation.
Can I combine the battery reduction and under-1.8-kW exception?
The CEC FAQ says not to combine those exceptions to avoid the systems. Follow the selected provision and its full conditions rather than stacking favorable calculations.
Does a small shaded roof automatically mean no PV?
Not without the applicable SARA assessment and exception conditions. Chapter 7 discusses individual roof areas and other available areas; document the actual site rather than guessing.
Does an ordinary addition trigger these new-home PV mandates?
The CEC says the cited PV requirements do not apply to additions or alterations to existing buildings. A new detached ADU is a different scope; verify classification and other applicable requirements.
Which date decides whether this is a 2025-code package?
Use the AHJ-recorded permit-application date. Applications on or after January 1, 2026 use the 2025 Energy Code; permit issuance or equipment purchase is not the controlling substitute.
10Turn the question into a scoped documentation request
Title 24 Lab is a provisional brand for design-phase energy-document preparation. Field testing, acceptance testing, registry fees, CALGreen documentation and AHJ fees are excluded. This is educational information, not legal advice; confirm the application date, classification and requirements with the AHJ. Review the shared published pricing, then upload the current plans and identify unresolved inputs. Submission is not payment, production acceptance or permit approval.
See published residential and commercial pricingWhat to send with the plansGet a quote / upload plans privately
Sources
- CEC: 2025 Energy Code and January 1, 2026 effective date
- CEC 2025 single-family solar PV FAQs: applicability, additions and ADUs
- CEC 2025 Single-Family Compliance Manual, Chapter 7: PV and battery storage
- CEC 2025 Reference Appendices: JA2, JA12, JA13, JA16 and verification procedures
- CEC 2025 Energy Code: adopted standards, including §§110.3, 110.4, 150.0 and 150.2
- CEC: 2025 single-family CF1R, CF2R and CF3R forms