The NEC 2023 changes with the most practical effect on solar plan sets are Exception 2 to 690.12, which removes rapid shutdown requirements for PV on non-enclosed detached structures such as carports and solar trellises; the consolidation of rapid shutdown labeling into 690.12(D); and the continued availability of the UL 3741 PV hazard control system pathway as an alternative to module-level power electronics. If you prepare solar permit plan sets across multiple states, the harder problem is not the 2023 changes themselves. It is drawing to three or four different code years at the same time.
Code adoption is a state and, in some cases, local decision. A firm working nationally may routinely produce NEC 2017, 2020, and 2023 solar plan sets in the same week. Getting the code edition wrong on the cover sheet can result in a correction on its own, independent of whether the underlying solar design is correct.
The Rapid Shutdown Requirement and How It Evolved
NEC 690.12 exists because switching off an inverter does not de-energize the DC conductors running from the array. Firefighters performing rooftop operations could be exposed to live conductors with no way to shut them down. The code response has evolved across four cycles.
| Code Year | What Changed |
|---|---|
| 2014 | Rapid shutdown introduced, applying outside the array boundary only |
| 2017 | Inside-array-boundary requirement added: 80V within 30 seconds, which made MLPE effectively necessary for many string systems |
| 2020 | UL 3741 PV hazard control system added as a listed compliance path; one initiator per PV system |
| 2023 | Exception 2 added for non-enclosed detached structures; labeling consolidated into 690.12(D) |
The core requirement has been stable since 2017. Controlled conductors outside the array boundary must drop to 30V within 30 seconds of initiation. Conductors inside the array boundary must drop to 80V or less within the same window, unless the installation uses a listed PV hazard control system.
The Two Compliance Pathways
Module-Level Power Electronics
An optimizer or microinverter is installed at each module. This approach has high AHJ familiarity, is well understood by reviewers, and remains common for residential and many commercial rooftop projects. Component selection must match the certified system.
For solar permit plan sets, the equipment schedule, rapid shutdown method, module-level components, and associated wiring must all be coordinated with the listed system requirements.
PV Hazard Control System Under UL 3741
UL 3741 evaluates the array as a complete system, including modules, racking, and wiring, rather than requiring de-energization at each module. A listed PV hazard control system can satisfy 690.12 without MLPE on the roof.
The practical trade-off:
| Consideration | MLPE | PVHCS (UL 3741) |
|---|---|---|
| Roof equipment | Electronics at every module | Modules, racking, and wiring only |
| AHJ familiarity | High | Growing, still inconsistent |
| Component flexibility | Moderate | Low; full system listing required |
| Plan review documentation | Standard | More detailed listing documentation |
| Typical fit | Residential, most C&I rooftop | Larger commercial string-inverter designs |
The PVHCS path opens compliant string-only designs on commercial projects where microinverters may not scale economically. The trade-off is greater documentation depth during solar permit plan set review because fewer reviewers see these systems regularly.
The Exceptions Worth Knowing
Non-enclosed detached structures (2023, Exception 2): PV equipment and circuits on parking shade structures, carports, solar trellises, and similar structures are not required to comply with 690.12. The committee rationale is that firefighters do not perform rooftop ventilation on open carport structures, so the hazard addressed by 690.12 does not arise. This aligns with IFC Section 1205.2.
Two practical notes matter when preparing a solar permit plan set. First, cite the exception directly on the drawing. A reviewer who does not see the citation may interpret the absence of rapid shutdown as an omission. Second, “non-enclosed” is critical. If the structure is enclosed, the exception does not apply.
Ground-mount arrays: These are exempt where conductors enter only a building used solely to house PV equipment, such as an inverter shed or combiner enclosure. If those conductors enter a dwelling or any occupied building, rapid shutdown applies. Earlier code language was ambiguous here, and some inspectors may still carry the older interpretation, so confirming the requirement with the AHJ can be worthwhile.
Labeling Under 690.12(D)
Labeling is prescriptive, and reviewers read it literally. The rapid shutdown switch label under 690.12(D)(2) must be located on or within three feet of the switch, with the wording “RAPID SHUTDOWN SWITCH FOR SOLAR PV SYSTEM,” reflective, all capitals, white on red, with letters at least 3/8 inch high.
The solar plan set should include a labeling schedule showing the required text, color, letter height, material, and placement for every required placard. Reviewers can flag labeling and signage details even when the underlying PV design is correct.
Interconnection Under 705.12
The 120% busbar allowance under 705.12(B)(3)(2) remains one of the most-corrected calculations in residential solar permit plan sets, not because it is difficult, but because the supporting arithmetic is frequently omitted.
Show the work:
- Busbar rating
- Main overcurrent device rating
- PV backfeed breaker rating
- The sum compared against 120% of the busbar rating
Supply-side connections under 705.11 avoid the busbar limitation but bring their own documentation requirements, including tap conductor sizing and disconnect location. These requirements may also be governed by the utility’s standards rather than the NEC alone.
Working Across Mixed Code Years
This is the operational reality that code discussions often skip. Adoption is uneven. A national solar installer may have active jurisdictions using NEC 2017, 2020, and 2023 simultaneously, with local amendments layered on top of each.
For teams producing solar permit plan sets at volume, this requires:
- Per-jurisdiction code tracking, rather than applying one company standard everywhere
- Cover sheet code declarations naming the adopted electrical, building, fire, and residential editions for that specific AHJ
- Amendment awareness, because fire setbacks and access pathways in particular are frequently amended locally
- Version discipline on templates, since reusing a set built for a 2023 jurisdiction in a 2017 jurisdiction can silently carry forward the wrong assumptions
Vishtik tracks adopted code editions and local amendments across 7,000+ AHJs and 800+ utilities, supporting a 98.7% approval rate across multi-state project volume.
For solar installers and EPCs working across multiple jurisdictions, the goal is not simply to create a compliant PV design. It is to produce a solar permit plan set drawn to the requirements of the reviewing jurisdiction, with the correct code edition, local amendments, documentation, and utility requirements built into the package.
Vishtik helps solar teams manage that complexity with jurisdiction-specific solar permit design and plan sets built for AHJ review.
