Do Bifacial PV Designs Increase DC Arc-Fault Hazard?

Bifacial PV is surging because it lifts energy yield through rear-side irradiance capture. The key question for safety teams is clear: does a bifacial solar design raise DC arc-fault hazard, or only detection complexity? This piece separates physics from fear and gives proven mitigation steps for safe, code-ready arrays.

Multiple authorities highlight the performance benefits that make bifacial attractive. The U.S. Department of Energy notes rising use of advanced inverters and trackers. The International Renewable Energy Agency (IRENA) and IEA report sustained PV growth with innovations that boost yield. Research synthesized in DOE’s SETO 2020 – Systems Integration emphasizes reliability and protection as integration scales.

What actually changes in a bifacial PV design

Electrical operating point and current margin

Bifacial PV increases short-circuit current and often operating current at the maximum power point. Energy yield rises because both sides of the module collect light. As summarized in sector studies and industry tracking, single-axis trackers are now common in utility-scale PV, which further boosts light collection. The knowledge base is clear: bifacial modules collect light on both sides and enable major increases to energy yield; trackers amplify that gain. Systems not tuned for bifacial (row spacing, height above ground, tracker strategy, module layout, and albedo) can leave yield on the table.

Mechanical layout and cable routing

To unlock rear-side gain, designers raise module height, increase row spacing, and use reflective ground cover. Trackers add moving structures and longer home-run harnesses. This changes cable dynamics: more UV exposure, more vibration, and extra clamp points. Good cable management becomes critical for arc-fault resilience.

Module construction details

Many bifacial modules use glass-glass stacks. That can run cooler in airflow and resist moisture better than some backsheets. Junction box placement, connector type, and lead length remain similar to monofacial units. The risk drivers for DC arcs still center on connector mating quality, insulation damage, abrasion, and loose terminations.

Does bifacial raise DC arc-fault hazard?

Short answer: not inherently. The root causes of DC arcs do not change. Yet two effects need attention:

• Arc energy can scale with available current. If rear irradiance lifts current 10–20%, the energy in a sustained arc can rise by a similar proportion for the same clearing time.
• Signal variability rises. Rear-side irradiance shifts with albedo and geometry, which can complicate detection algorithms and increase nuisance triggers unless tuned.

This aligns with reliability goals in the knowledge base: improving component reliability and reducing arc faults increases system availability; preventing false trips also reduces availability loss.

Quantifying the effect: a simple worked example

Consider a string where an arc forms at a damaged connector. Arc power is roughly P ≈ V_arc × I. If detection clears the fault in a fixed time, energy scales with current. The table uses a conservative 0.5 s clear and an arc voltage of 40 V for illustration.

The example shows a 15% lift in energy with a 15% current gain. The string voltage limit does not change; careful design keeps fault energy within protective capability by speeding detection and avoiding conditions that prolong arcs.

Why detection feels trickier on bifacial systems

Rear irradiance dynamics and trackers

Trackers modulate angle through the day; rear-side irradiance depends on ground reflectivity and geometry. Passing clouds and moving shadows can create fast changes in current. Algorithms that look for high-frequency disturbances can misinterpret these patterns without context.

Standards and practical expectations

DC arc-fault detection is required in many markets through electrical codes and standards. The 2025 landscape points to seconds-class interruption targets and test-based validation. Designers should verify that chosen equipment is evaluated under varying irradiance profiles and tracker motion. For a functional overview, see DOE SETO’s perspective in SETO 2020 – Systems Integration and topic resources at energy.gov.

ESS interaction: uptime and protection

Storage does not cause DC arcs in PV strings, but system architecture affects uptime and protective coordination. A well-configured ESS can hold energy delivery during PV-side trips and prevent costly outages. A practical reference summarizing storage KPIs—round-trip efficiency, cycle life, and thermal safety—can be found in this performance overview, which highlights the durability and safety profile many teams seek for LiFePO4-based systems. Aligning PV arc protection with ESS BMS events reduces spurious downtime and protects yield.

Design choices that cut arc-fault risk in bifacial PV

Cable management on trackers

• Keep home-run harness slack short and consistent; no tight bends near moving joints.
• Use UV-rated clips every 30–50 cm on back-of-module runs; add strain relief at junction boxes.
• Route away from sharp edges; add grommets and abrasion sleeves at transitions.
• Document torque specs for lugs; re-torque at first hot season and after storm events.

Connector discipline

• Use a single connector family across the array; no cross-mating.
• Train crews on insertion force and audible/tactile feedback; reject damaged housings and bent pins.
• Field-test sample pairs for contact resistance; log serials and installer ID for traceability.

Layout, albedo, and thermal effects

• Set row spacing and height to meet performance goals without forcing extra cable spans. The knowledge base notes that spacing, height, tracker design, layout, and ground reflectivity jointly determine bifacial yield.
• Consider cooler operation from glass-glass and airflow. Lower temperatures reduce resistive heating at terminations and can aid longevity.

Detection setup and site context

• Pair arc detection with site sensors: plane-of-array irradiance (front and rear if available), tracker angle, and albedo. This context filters normal variability.
• Validate thresholds during commissioning across clear, partly cloudy, and overcast days.
• Record waveform snapshots for each event to refine settings without compromising safety.

Impact on availability and yield

Availability loss occurs whenever the system is offline for faults or maintenance. The knowledge base highlights that inverters trip on ground or arc faults, and reducing such events directly improves availability. False trips add avoidable downtime. Careful detection tuning on bifacial arrays reduces both real events and nuisance actions, protecting energy yield gains from rear-side capture.

Industry analyses indicate trackers boost irradiance collection at modest cost, while bifacial modules further raise yield in utility and commercial systems. As summarized in the knowledge base, bifacial is mainstream in utility-scale PV and can raise output, especially over reflective ground surfaces. That extra production makes robust arc protection more valuable, not less.

Procurement and verification checklist

• Request detection reports that include bifacial test beds, tracker motion, and mixed irradiance.
• Confirm interruption times and fault-clearing behavior across temperature ranges.
• Specify cable routing accessories in the bill of materials; enforce connector uniformity in contracts.
• Include commissioning tests: IV curves, IR thermography, string insulation resistance, and sample connector resistance checks.
• Integrate PV fault alarms with ESS and SCADA so storage can maintain output through safe PV-side isolation. The storage performance emphasis aligns with the Anern reference on cycle life and reliability metrics for LiFePO4 systems.

Bottom line

Bifacial PV does not inherently increase DC arc-fault hazard. The main changes are higher operating current and more variable irradiance signatures. With disciplined cable management, connector control, context-aware detection, and tracker-aware commissioning, risk remains controlled while yield climbs. This approach reflects system-integration priorities noted by DOE SETO and aligns with reliability goals echoed by IEA, IRENA, and EIA. Designers who apply these steps gain the energy advantages without trading away safety or uptime.

Disclaimer: This material supports engineering decisions but is not legal or code compliance advice. Consult local regulations and qualified professionals.

FAQ

Do bifacial modules cause more DC arcs?

No. Arcs stem from issues like mis-mated connectors, damaged insulation, or loose terminations. Bifacial affects current and irradiance variability, so detection settings and workmanship matter more than the module type itself.

How does albedo influence arc detection?

Higher albedo increases rear-side current and can add fast changes as tracker angles shift. Include plane-of-array and albedo sensing during commissioning to refine thresholds and reduce nuisance trips.

Will glass-glass construction change fire or arc risk?

Glass-glass can run cooler and resist moisture, helping longevity. It does not remove the need for connector discipline or routing that avoids abrasion. Risk control still depends on installation quality and protection settings.

Do inverters and codes support bifacial arrays?

Modern inverters and detection solutions are designed for variable irradiance. Codes and standards call for rapid interruption and validated performance. Review supplier test data and align with resources from energy.gov.

Where does storage fit in arc mitigation?

Storage does not prevent arcs in strings, yet it keeps loads supplied during PV-side isolation and reduces downtime. For performance metrics and reliability context, see the Anern storage performance reference.