Napa County

A city address is usually permitted by the city, not the county — but not always, and some authorities keep building and hand electrical to someone else. Getting this wrong costs the whole submittal, because every requirement below belongs to whoever actually holds jurisdiction. Check the overlays in the same pass: an HOA, a historic district, a windstorm certification or a system-size cap can reshape the design, and all of them are cheaper to find now than after the array is laid out.

• Is this authority the AHJ for residential solar at this address? Yes 95% · department page / ordinance
• What does this authority permit itself, and what does it delegate? Both 95% · ordinance
• Is a permit required for a residential rooftop PV system? Yes 95% · ordinance
• Is there a separate electrical permit, or is it combined? Combined 75% · published checklist (PDF, dated 08/01/2024)
• Is a HOA or architectural approval required first? No 90% · ordinance
• Is there a historic-district review? No, not for a typical unincorporated residential parcel 60% · ordinance TOC (absence checked)
• Is a wind or windstorm certification required? No 70% · ordinance (absence checked)
• Is a Specific Use Permit or Council approval ever required? Only if the building official makes a written finding, based on substantial evidence, that the system would have a 'specific, adverse impact' on public health/safety with no feasible mitigation — otherwise the permit is nondiscretionary and no Use Permit or Board of Supervisors approval is required 90% · ordinance
• Is there a system-size cap on residential generation? No absolute cap, but the streamlined 'small residential rooftop' process (Ch. 15.14 Art. III) only applies to systems ≤10 kW AC nameplate (or ≤30 kW thermal); larger residential systems fall outside that expedited definition and get standard (non-AB2188) permit review 85% · ordinance

Several authorities require the electrical permit to be pulled by a licensed electrician, or require the contractor to be registered with them BEFORE applying. Registration is not same-day. This is second on the list rather than fourth because it is the step most likely to stop the job before the drawings matter.

• Who is allowed to pull the electrical permit? Licensed electrician 60% · published checklist
• Must the contractor be registered with this authority before applying? No 55% · department page (absence checked)
• Is a homeowner permitted to self-install and self-permit? Ambiguous — general CA owner-builder permitting is allowed, but the County's own checklist requires the electrical single-line be signed by a C10/licensed installer or PE, not a homeowner 50% · published checklist

Almost everywhere wants a site plan, a one-line or three-line electrical diagram, equipment cut sheets with listings, and a structural attachment detail. Build it against the published checklist rather than the last jurisdiction you worked in — the checklist is what the reviewer marks against.

• What documents make up a complete submittal? Title page; site plan; roof plan with solar layout showing all setbacks (or array layout for ground-mounted); single-line electrical (stamped by EE or signed by C10/licensed installer with license #); plan of all required labels; attachment details; footing details + signed structural calcs for ground-mounted array mounting; supplemental: equipment cut sheets, structural calcs (roof loading), completed Agent Authorization Form if applicable 95% · published checklist (PDF)
• How many copies, and in what format? Electronic only, via the Online Permit Center: one condensed, bookmarked PDF for the plan set; supplemental documents uploaded individually; wet-signature pages must additionally be submitted as physical hard copies because the County's permitting software is not compliant with Gov. Code §16.5 e-signature rules 90% · ordinance + published checklist
• Is a site plan required, and what must it show? Yes — must show the roof plan with solar layout and all required setbacks, or the array layout for ground-mounted systems 95% · published checklist
• Is a one-line / three-line diagram required? Yes 95% · published checklist

Most authorities now take the whole application through a portal, and several states cap or constrain what a residential solar permit may cost. Check whether plan check is billed separately before you quote the job.

• Which permit portal does this authority use? Online Permit Center 95% · department page
• Can the whole application be completed online? No 90% · ordinance
• What does a residential solar permit cost? $450 flat for residential systems 15 kW AC or less; $450 + $15 per kW above 15 kW for larger residential systems 95% · published fee schedule (PDF)
• How is the fee calculated? Tiered 90% · published fee schedule
• Is there a separate plan-check fee? No 65% · published fee schedule

Interconnection is a separate process from the permit and usually the longer pole. Where the utility does not depend on the permit being issued, running both at once is the single biggest saving available on a residential job.

• What is the stated plan-review turnaround? Ordinance requires expedited/'as soon as reasonably practicable' review for eligible small residential rooftop systems; the County's general plan-review tiers are Express 3–5 business days, Quick 7–10 business days, Standard 28 business days 70% · department page + ordinance
• How long is an issued permit valid before it expires? 365 days (one calendar year) from issuance to commence work; the permit also expires if no inspection is requested/performed within 180 days; up to three 180-day extensions may be granted before the permit becomes null and void 95% · ordinance
• Which utility handles interconnection here? Pacific Gas & Electric (PG&E) 65% · secondary source

The NEC edition a jurisdiction enforces is often a cycle behind the newest one published, and local amendments sit on top of it. Rapid shutdown, conductor sizing and labelling all change between editions, so the edition in force is the first thing to establish, not the last.

• Which NEC edition is in force? 2023 95% · adopting ordinance
• Which building code edition is in force? 2025 California Building Code (based on 2024 IBC) and 2025 California Residential Code (based on 2024 IRC), Title 24 Parts 2 and 2.5 95% · adopting ordinance
• Which fire code edition is in force? 2025 California Fire Code (based on 2024 IFC), Title 24 Part 9 95% · adopting ordinance
• Are there local amendments to any of the above? Yes — extensive local amendments across building, electrical and fire chapters (winery-cave provisions, roof-covering Class A requirement, sprinkler thresholds, PV working-space clarification at Art. 690.4(I), disconnect location at Art. 225.32, ground-mount vegetation/setback rule at CFC 1205.5.1, ESS scope at CFC 1207.1, etc.) 95% · ordinance
• What is the installation judged against? 2025 CEC (2023 NEC base) Article 690, 2025 CBC/CRC, and 2025 CFC, all as locally amended, plus the County's own Solar Photovoltaic Installation Guidelines (Ch. 15.14 Art. II, adopting the CAL FIRE/OSFM 2008 guideline 'as may be amended') and the Small Residential Rooftop Solar ordinance (Ch. 15.14 Art. III) 90% · ordinance

Ridge setbacks and roof access pathways are fire-service requirements and they constrain the array layout. They are the most common cause of a redesign after the fire department comments on a plan set.

• What ridge setback and access pathways are required? Rooftop systems: standard 2025 CFC §605.11 pathway/setback provisions apply (adopted by reference, not locally amended). Ground-mounted arrays: a local amendment requires a 10-ft clear, brush-free perimeter around the array plus a noncombustible base (gravel or equivalent) under the array and its electrical equipment 80% · ordinance

Which rapid-shutdown rule applies follows directly from the NEC edition in force, and the initiation device has to be at a location the fire service can reach and identify. This is inspected, and it is labelled.

• Is rapid shutdown required, and to which NEC edition? Yes, per NEC Article 690.12 (Rapid Shutdown) as incorporated via the 2023 NEC / 2025 CEC, which the County adopted unamended on this point 80% · adopting ordinance

The NEC sets a baseline for permanent markings at the service equipment and the disconnecting means. On top of that, an authority may specify its own wording, and the utility may specify more again. Where any of them writes its own text, a generic off-the-shelf label set will not pass — this is the detail most often fixed on a return visit.

• Which placards does this authority require at the service equipment? Standard NEC Article 690 disconnect/warning labels (e.g. 690.13, 690.56) and CFC §605.11 rooftop marking, plus whatever the CAL FIRE/OSFM 'Solar Photovoltaic Installation Guideline' (2008, as amended) specifies — that guideline is adopted by reference in Ch. 15.14 Art. II but its current text could not be retrieved to confirm exact placard content 55% · ordinance (adoption only; underlying guideline unreachable)

Where the AC disconnect must sit relative to the meter is usually the utility's rule, not the building department's. Battery storage frequently carries its own permit, its own inspection and its own fire conditions.

• Where must the AC disconnect be, relative to the meter? The County's own amendment (Art. 225.32) requires the disconnecting means be outside the building, readily accessible, and nearest the point of conductor entrance — a general rule rather than one stated relative to the utility meter specifically 55% · ordinance
• Must equipment be on a specific approved list? Yes 80% · ordinance
• Are batteries permitted, and under what conditions? Yes — batteries/Electrical Energy Storage Systems in Group R-3 and R-4 occupancies (and accessory Group U structures) are permitted subject to compliance with California Fire Code §1207.11 85% · ordinance
• Is there a separate ESS permit or inspection? No indication of a distinct stand-alone ESS-only permit/inspection; ESS compliance is folded into the standard building/fire permit and inspection process under CFC §1207.11 55% · ordinance (absence checked)
• Is a ground mount treated as a structure? Yes, functionally 70% · published checklist + ordinance
• Is there a local rule on service upgrades or busbar sizing? No local rule on service-upgrade sizing or busbar rating beyond unamended NEC 705.12; the County's only PV-specific electrical amendment is a working-space clarification (Art. 690.4(I)) requiring NEC 110.26 clearances around inverters 65% · ordinance (absence checked)
• Is a specific mounting system or attachment spacing required? No County-specific mounting/attachment-spacing standard found beyond requiring 'Attachment Details' and structural calculations/roof-framing information in the submittal 60% · published checklist (absence checked)

Booking is a portal, a phone call or an email depending on the authority, and the notice required is rarely zero. Book before the work is finished rather than after — the lead time, not the work, is usually what sets the date.

• How is an inspection booked? Online Permit Center (registered users), automated phone system (707-253-4416, call or text), or text line (866-307-2630) 90% · department page
• How much notice is required? 2 business days 90% · ordinance
• Are same-day or AM/PM windows offered? Ordinance guarantees a 2-hour inspection window for eligible solar inspections; general department practice otherwise is to call between 7:45-8:30 a.m. on the inspection day for a same-day estimated arrival time rather than a fixed AM/PM slot system 75% · department page + ordinance

Some authorities inspect their own solar work; some delegate it, and a few do not inspect the PV equipment itself at all. Who is coming determines what they will look at.

• Does this AHJ perform its own final solar inspection? Yes 85% · ordinance
• If delegated, to whom? Not delegated for building/electrical/fire in general; the one carve-out is that unincorporated land within the American Canyon Fire Protection District follows that district's own fire ordinances rather than the County Fire Code 75% · ordinance

A rough-in or mid-roof inspection, where one is required, has to happen before the work it covers is closed up. Missing a stage means opening something back up, and it is the most expensive kind of correction.

• Which inspections are required, and in what order? For systems eligible for the expedited process: only one consolidated inspection by the Building Division (plus a separate fire inspection only if no Cal Fire agreement exists) 85% · ordinance
• Is a rough-in or mid-roof inspection required? No 80% · ordinance

The approved plan set, the permit, and the equipment listings should be on site and reachable. Inspectors routinely verify that installed equipment matches what was approved, and that the labels are the ones the plan set promised.

• What must be on site at inspection? The issued permit posted at the job site, the approved plans, and the inspection card 85% · department page
• Does the inspector verify labels and listings? Likely yes, though not stated as a discrete checklist item 60% · published checklist (inference)

Passing gives you a final or an equivalent sign-off. That is not the same as permission to operate: PTO comes from the utility, and who tells the utility the inspection passed varies. A system left switched off for weeks is usually waiting on this handover.

• What is issued on pass? Final 75% · department page
• Is there a re-inspection fee? Hourly rate, currently $257/hr ($276.28/hr including the 7.5% General Plan Surcharge) for 'Additional Inspections or Re-Inspections' under the Building Division 80% · published fee schedule (PDF)
• How are corrections issued and cleared? Incomplete applications receive a written correction notice detailing all deficiencies for resubmission; if an inspection fails, a subsequent (re-)inspection is authorized (but need not carry the expedited-process guarantees of the first) 80% · ordinance