Reference · Permitting

What your AHJ will want, and what only they can tell you

Describe the project and this lays out the approvals to open, the code articles in play, the order the inspections come in, and the documents review will ask for — then hands you the questions to put to your building department and your utility.

It does not know your jurisdiction, and will not pretend to. There are tens of thousands of authorities having jurisdiction in the United States. Which edition of the NEC, IBC, IRC or IFC each has adopted — and what it has amended on top — varies by state and by city and changes on adoption cycles. None of that is loaded here. Everything below is what usually applies, written so you can confirm it. The adopted edition is a question for your AHJ, and the questions are the point of the page.

Showing the checklist for a residential rooftop system without storage. Turn on JavaScript to adjust it for your project.

Approvals to open

Building permit — Covers the structure: how the array is attached, and what it adds to the loads the building already carries.
Electrical permit — Covers the wiring, the overcurrent protection, the disconnects, the labelling and the grounding. Some jurisdictions fold it into the building permit; some do not.
Utility interconnection application — A separate track from the permit, with its own forms, its own review and its own queue. Starting it late is the most common scheduling mistake on a first project.
Net metering or export agreement — The contract that decides what exported energy is worth. Often bundled with the interconnection application, sometimes not.
Permission to operate (PTO) — The last gate. It comes after the AHJ has signed off AND the utility has accepted the interconnection. Until it arrives the system may not run.

Codes in play

NEC Article 690 — Solar photovoltaic systems — The core PV article: conductor sizing and ampacity, disconnects, rapid shutdown, arc-fault protection, grounding and the required labels.
NEC Article 705 — Interconnected power production sources — How the system ties into the existing service: busbar and feeder calculations, supply-side versus load-side connections, and the limits on each.
IRC — structural provisions — One- and two-family dwellings. Covers what the roof framing can carry once the array, its mounts and any ballast are added.
ASCE 7 — Wind, snow and seismic loads — Sets the loads the attachments and the structure are designed against. The building code names which edition of it applies.
International Fire Code — roof access and marking — Access pathways, setbacks from ridges and the marking that tells a fire crew what is energised. Requirements differ sharply between one- and two-family dwellings and other occupancies.

Inspection sequence

Mounting and flashing inspection — Sometimes required before the modules go on, so the attachments and their flashings are visible. Worth asking about early - it is the inspection most often missed, and it cannot be done retrospectively.
Rough-in / mid inspection — Conduit, raceways, conductors and grounding, before anything is closed up or buried.
Final electrical inspection — The completed installation: terminations, overcurrent devices, disconnects, rapid shutdown function, and every required label actually present and legible.
Final building inspection — Structural attachment, any roof penetrations and weatherproofing, and the as-built matching the approved plan set.
Utility meter exchange or witness test — The utility's own visit: the meter is swapped for one that measures both directions, and on larger systems the protection settings are witnessed.

Document pack

Site plan — The property, the structure, the array, the equipment locations and the point of interconnection, with setbacks and access dimensioned.
Single-line diagram — Every conductor, overcurrent device, disconnect and grounding point, with sizes and ratings. This is the drawing the electrical reviewer actually reads.
Electrical calculations — Voltage at the lowest expected temperature, conductor ampacity with its derates, and the busbar or feeder calculation under NEC 705.
Module datasheet and listing — The spec sheet plus evidence the module is listed to the PV module safety standard (UL 61730, which harmonised the earlier UL 1703).
Inverter datasheet and listing — Listed to UL 1741. Where the utility requires grid-support behaviour, the relevant supplement (SA or SB, aligned to IEEE 1547) is what the interconnection reviewer looks for.
Racking listing and engineering — UL 2703 covers mounting systems for bonding, grounding and mechanical loading; UL 3703 covers trackers. The manufacturer's load tables are what the structural letter is built on.
Rapid shutdown equipment listing — NEC 690.12 requires equipment listed for the purpose. The reviewer will check that the module-level device and the initiator are a listed combination, not two parts that happen to work.
Structural evaluation letter — A stamped letter that the existing framing can carry the new loads, with the attachment pattern it assumed. Usually required for commercial, and increasingly for residential.
Placard and labelling schedule — The NEC prescribes specific wording, and in places specific colours and durability, for disconnects, rapid shutdown and the service point. A missing or faded label is a routine reason for a failed final.
Interconnection application package — The utility's own forms, usually wanting the single-line, the equipment listings and the inverter's grid-support certification. Its requirements are set by the utility, not by the AHJ, and the two lists rarely match exactly.

Where the adopted edition actually comes from

Model codes are written nationally and adopted locally. The NEC is published by the NFPA, the IBC, IRC and IFC by the ICC — but none of them applies anywhere until a state or a local government adopts it, usually some editions behind current, and usually with amendments. Two towns an hour apart can be on different editions.

The model code is publishedNFPA and ICC issue on a three-year cycle.
A state adopts an editionOften with statewide amendments, sometimes leaving it to localities.
The local AHJ adopts and amendsIt may lag the state, and may add its own requirements.
Your plan set is reviewed against thatWhich is why the edition is the first thing to establish.

The authoritative answer is the building department itself. The NFPA and ICC both publish adoption maps that are a reasonable starting point, and a growing number of jurisdictions run automated residential review through SolarAPP+ — but confirm any of it with the AHJ before drawing.

The three things that go wrong

Starting interconnection late

The utility is not the AHJ. It has its own application, its own queue and its own timescale, and permission to operate comes after both tracks finish. On most projects the utility, not the building department, is the critical path.

Missing an inspection that cannot be redone

Anything that gets covered — pile embedment, roof attachments and flashings, buried conduit — has an inspection before it is covered. Finding out afterwards means opening it back up.

Designing against the wrong edition

Rapid shutdown, labelling and busbar rules all moved between recent NEC editions. A plan set drawn to the wrong one is a redraw, not a correction.

Questions, for a residential rooftop system

The worksheet above tailors these to your project. Rendered here so they are readable without it.

Which edition of the NEC have you adopted, and do you have local amendments to it?
Which building code edition applies, and which edition of ASCE 7 does it reference for wind and snow?
Do you require a separate electrical permit, or is it part of the building permit?
Do you accept electronic plan submission, and do you use SolarAPP+ or another automated review?
What is your current plan review turnaround, and your inspection lead time?
Which inspections do you require, and in what order? Is a mounting or pre-cover inspection needed before the modules go on?
Do you require a licensed engineer's stamp on the structural letter, and must that engineer be licensed in this state?
What roof access pathways and setbacks do you enforce, and does that differ for this occupancy?
Is there anything about solar submissions that you see done wrong most often?

What the parts are Federal rates & thresholds Import duty calculator

Permitting is local; the rates and thresholds elsewhere in this reference are federal. Neither is advice, and neither replaces your AHJ, your utility or a licensed professional.