2025 Update: NEC 690.11 and IEC 63027 for PV Arc-Faults

PV arc faults remain a leading fire risk in DC arrays. In 2025, most jurisdictions still enforce arc-fault protection on PV circuits on or in buildings. Two standards shape design and product choices: NEC 690.11 in North America and IEC 63027 across many international markets. This page maps the latest expectations, shows design tactics that reduce nuisance trips, and helps you pass inspections with confidence.

Why arc-fault standards matter in 2025

Rapid PV cost declines bring larger arrays to rooftops. Safety must keep pace. According to Renewable Power Generation Costs in 2024, the global weighted average total installed cost for utility-scale PV commissioned in 2024 fell to about USD 691/kW, 87% lower than in 2010. Low costs amplify deployment, which raises the stakes for clear arc-fault rules and reliable protection.

The broader standards ecosystem also keeps tightening. As summarized in Grid Codes for Renewable Powered Systems, grid codes and product standards increasingly reference IEC/IEEE catalogs to secure safe, high-uptime operation. Early foresight on PV scaling from the IEA Technology Roadmap: Solar Photovoltaic Energy 2010 mapped the learning-curve path we see today. Safety layers such as arc detection and rapid shutdown are part of that maturing stack. For a broad program view, see Energy.gov – Solar Energy.

Core provisions at a glance

NEC 690.11 (DC arc-fault protection)

NEC 690.11 requires listed DC arc-fault protection on PV systems on or in buildings. Devices must detect arcing conditions, interrupt the fault, and provide annunciation. Protection usually sits inside the inverter or in a combiner/array-level device. Expect manual or system-controlled reset logic, defined trip conditions, and coordination with other safety features such as rapid shutdown. Adoption and interpretations vary by Authority Having Jurisdiction (AHJ). Always confirm local amendments.

IEC 63027 (Arc fault protection in PV systems)

IEC 63027 sets performance requirements for Arc Fault Protection Equipment (AFPE) in PV DC circuits. It defines detection capability for series faults, a test regimen, and response behavior (interruption/mitigation and annunciation). Manufacturers certify AFPE against IEC test profiles to show sensitivity to arc signatures while filtering normal switching noise and irradiance-driven variability.

NEC 690.11 vs IEC 63027—technical comparison

Note: Always cross-check your product datasheet for the exact listing or certification path and the standard revision it references.

Design patterns that cut risk and nuisance trips

1) Wiring, connectors, and layout

• Use matched, properly rated MC4-type connectors from the same family. Do not mix manufacturers or crimp systems.
• Torque terminations per datasheet. Re-torque after thermal cycling if the hardware requires it. Record values in the commissioning sheet.
• Avoid rubbing points and tight bend radii. Use UV-stable clips. Maintain string homeruns with tidy, strain-relieved routes.
• Reduce inline splices. Every splice is a potential arc initiation point under vibration and moisture ingress.

2) String engineering

• Match string lengths and orientation to limit mismatch noise that can resemble arc signatures.
• Keep within inverter’s MPPT voltage/current window across local temperature extremes. Model Voc and Vmp with site Tmin/Tmax.
• Use fusing for parallel strings to contain fault energy and help arc-interruption.

3) Filtering real arcs vs normal switching

• Modern AFPE uses time-frequency features and signature envelopes, not simple thresholds. Firmware updates often improve filtering.
• If nuisance trips appear during partial shading or rapid irradiance ramps, record waveforms and consult the inverter’s event log. Apply the latest approved firmware and retry functional tests.

Commissioning sequence that satisfies inspectors

• Visual inspection: connectors, labels, conductor support, and enclosure ingress ratings.
• Mechanical checks: torque values for terminals, gland nuts, and rail bonds.
• Electrical baseline: insulation resistance, polarity check, open-circuit voltage vs model, short-circuit current vs model.
• AFCI functional test: follow the manufacturer’s method. Verify annunciation and auto/ manual reset behavior.
• Rapid shutdown functional test: verify timing and boundary compliance, then repeat the AFCI test to check interaction.
• Document everything: capture photos, test sheets, firmware versions, and serial numbers.

These steps align with common AHJ expectations under NEC 690.11 and speed up approvals.

Arc faults near storage—what changes

Hybrid systems blend PV strings with a DC-coupled or AC-coupled Energy Storage System (ESS). The DC bus and battery circuits add conductors and terminations. Good news: LiFePO4 cells and smart BMS reduce thermal propagation risks on the storage side, yet DC arcs can still occur at lugs and disconnects if workmanship slips.

For a field-friendly checklist on storage-side performance baselines, see the sizing and performance tables in Ultimate Reference: Solar & Storage Performance. The piece highlights practical wiring and efficiency checkpoints for battery-integrated systems. It also shows typical residential DC levels for 48 V battery stacks and string DC ranges that align well with inverter MPPT windows. Reported round-trip figures for LiFePO4-based setups commonly sit in the 90–95% band, which reinforces the benefit of tight terminations and low-loss cabling to avoid heat that can precipitate arcing at weak joints.

Interoperability: arc-fault, ground-fault, and rapid shutdown

These layers must coordinate. If rapid shutdown pulls array voltage to a defined safe boundary, AFPE should not trip late or mask an event. Many manufacturers publish timing diagrams. Test both features in sequence and confirm clean event logs.

From the systems perspective summarized by IRENA’s Grid Codes overview, modern PV plants are expected to provide coordinated protection, clear signaling, and safe fault behavior across multiple devices. That same systems thinking helps at residential scale.

Costs, practicality, and 2025 adoption

Arc-fault capability adds electronics and certification, but the percentage impact keeps shrinking as PV prices drop. The cost trend reported in IRENA’s 2024 costs report shows installed costs around USD 691/kW on average for utility-scale builds. While rooftop installs vary, the direction is the same: safety features form a small share of system CAPEX. Earlier projections in the IEA 2010 PV roadmap anticipated falling module and system costs, which is now evident. That makes compliance-driven design more accessible to homeowners and small businesses.

What inspectors look for in 2025

• Clear labeling for arc-fault protection and rapid shutdown. Match labels to the device’s listing and the code section.
• Evidence of listing/certification (e.g., marking plate or datasheet excerpt) for the AFPE function.
• Commissioning record with AFCI functional test notes and pass results.
• Clean workmanship: proper connectors, strain relief, grommets, and no exposed conductors.

Practical arc-fault mitigation beyond the device

Material choices

• Use tinned copper for terminations in corrosive zones. Use anti-oxidant paste on aluminum lugs if specified.
• Select enclosures with appropriate NEMA/IP rating to limit moisture ingress that promotes tracking and arcing.

Operational monitoring

• Enable inverter arc-fault logging and alerts. Push events to a maintenance email to shorten response time.
• Thermal scans during the first sunny week catch hot joints early. Rework as needed.

Firmware and lifecycle

• Keep inverter/AFPE firmware current. Vendors often refine algorithms to reduce nuisance trips under fast irradiance ramps.
• Re-test annually, especially after array rewiring or storage upgrades.

Key takeaways for NEC 690.11 and IEC 63027 in 2025

• NEC 690.11 is widely enforced for PV DC circuits on or in buildings. It expects listed arc detection, interruption, and annunciation.
• IEC 63027 sets AFPE performance benchmarks for series DC arcs and is shaping product designs used globally.
• Better wiring, connector discipline, and documented commissioning cut both real risk and nuisance trips.
• Costs continue to fall, making robust arc-fault protection a small part of CAPEX while adding major risk reduction.

FAQ

Which systems need NEC 690.11 DC arc-fault protection in 2025?

Typically, PV DC circuits on or in buildings require listed arc-fault protection. Local adoption varies. Check your state/city amendments and device listings. This is not legal advice.

Does IEC 63027 cover parallel arcs?

IEC 63027 focuses on series DC arcs and AFPE performance. Parallel faults are mitigated through overcurrent protection, equipment ratings, and sound wiring design.

How can I reduce nuisance tripping without dulling protection?

Fix workmanship first: matched connectors, correct torque, neat routing. Then apply the latest approved firmware. Re-run the functional test and review logs.

How does arc-fault protection interact with rapid shutdown?

They should coordinate without masking each other. Test both features together during commissioning and confirm timestamps and messages in the event log.

What data supports the focus on arc safety today?

Deployment scales as costs fall. See IRENA’s 2024 costs report and the IEA PV roadmap. Safety features like AFCI maintain risk control as arrays grow.