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Solar PV systems represent the largest and most mature segment of DC power distribution. Unlike conventional AC systems, PV installations face distinct challenges: large exposed surface areas prone to direct and indirect lightning strikes, continuous DC voltage operation without natural zero-crossing points, and the presence of sensitive power electronics in inverters that can be damaged by voltages just 20% above rated values.
Standardization Framework
The cornerstone for PV surge protection is IEC 61643‑31, which specifies performance and safety requirements for SPDs connected to the DC side of PV installations rated up to 1,500 V DC. The standard covers devices for surge protection against both indirect and direct lightning effects. Notably, SPDs for PV systems with energy storage (batteries, capacitor banks) are explicitly excluded from this standard, highlighting the need for distinct solutions when storage is integrated.
Key Selection Parameters
Selecting SPDs for PV applications requires careful evaluation of several technical parameters. The maximum continuous operating voltage (UCPV) must exceed the array‘s maximum open-circuit voltage at the lowest ambient temperature, typically 1,000–1,500 V DC. The nominal discharge current (In) should be ≥20 kA for Type 1 SPDs, while the maximum discharge current (Imax) is typically ≥40 kA. Response time must remain below 25 nanoseconds, and the voltage protection level (Up) must be low enough to safeguard inverter electronics.
Unique PV Challenges
PV systems introduce two unique failure modes. First, DC arcs lack the natural zero-crossing of AC, making surge events more hazardous and potentially leading to persistent arcs that account for a significant proportion of solar-related fires. Second, insulation faults in the generator circuit can damage conventional SPDs. Advanced solutions such as DEHN‘s patented SCI principle incorporate combined disconnection and short-circuiting devices that provide safe electrical isolation under fault conditions.
BESS installations introduce a new dimension of overvoltage protection requirements due to the inherent vulnerability of battery cells and the catastrophic consequences of failure. Battery energy storage systems contain AC/DC converters with sensitive electronics and high-capacity batteries with low dielectric strength, creating explosion risks in case of arcing.
Risk Assessment and Standards
A risk assessment per IEC 62305‑2 should first determine whether an external lightning protection system is required. IEC 60364‑4‑44 addresses protection against voltage disturbances and electromagnetic disturbances, including transient overvoltages transferred via supply lines, while IEC 60364‑5‑53 covers SPD selection and installation. For AC-side protection, when lines entering BESS containers are overhead, Class I/Type 1 SPDs with Iimp ≥5 kA per conductor must be selected.
DC-Side Protection Challenges
A dedicated standard for DC SPDs in BESS applications is currently unavailable. The withstand voltage of live parts (e.g., battery poles) to ground is a function of environmental conditions including humidity and salinity, and must be limited to safe levels using appropriately selected DC SPDs with the Up < Uw criterion.
Perhaps most critically, surge shocks triggered by lightning induction and grid fluctuations are among the primary triggers for battery thermal runaway. UL 9540A provides a test methodology for evaluating thermal runaway fire propagation in BESS, conducting tests at cell, module, unit, and installation levels. This testing determines whether battery technology can undergo thermal runaway and evaluates fire and explosion hazards.
Multi-Stage Protection Strategy
Commercial and industrial PV+storage systems typically implement multi-stage surge protection: Type 1 SPDs at service entrances for direct lightning strikes, Type 2 at distribution panels for indirect surges, and Type 3 near sensitive electronics for final voltage clamping. Dedicated SPDs and voltage-clamping devices safeguard lithium-ion batteries against overvoltage and thermal runaway risks caused by transients.
As DC microgrids, data centers, and electric vehicle charging infrastructure proliferate, dedicated DC distribution lines are becoming increasingly common. These systems face unique protection challenges that differ fundamentally from both AC distribution and HVDC transmission.
New Standardization: IEC 61643‑41:2025
Published in 2025, IEC 61643‑41 represents a landmark advancement in DC surge protection, filling critical gaps for DC low-voltage power systems up to 1,500 V DC. The standard introduces several key innovations: a standardized testing framework with defined waveforms (10/350 μs and 8/20 μs), enhanced safety requirements including mandatory thermal disconnectors (TD+), a DC‑specific performance classification system (Type 1/2/3), and high short‑circuit current handling requirements up to 100 kA.
The standard covers DC systems from 48 V up to 1,500 V, with particular focus on the 1,000–1,500 V range used in modern ESS and renewable energy applications. SPDs for PV applications are explicitly excluded (covered by IEC 61643‑31), while railway applications may apply the standard when dedicated product standards do not exist.
DC arc flash presents unique safety hazards because DC current lacks natural zero‑crossing points. DC arcs sustain longer, cause deeper burns, require larger arc flash boundaries, and may necessitate higher‑rated personal protective equipment.
Several technological approaches address this challenge. Rapid Arc Control (RAC) spark gap technology significantly reduces energy input by splitting the discharge process into ignition, counter‑voltage buildup, and quenching phases. Multi‑chamber gap structures for power frequency arc quenching have been developed for 10‑kV systems. ArcZero technology integrates active arc quenching electronics directly into DC connectors, enabling safe device replacement under load.
Transmission-Level Considerations
For HVDC transmission lines, lightning stroke remains the primary cause of fault restarts, accounting for approximately 50–60% of such events. China has developed ±400 kV to ±1,100 kV DC line arresters to limit overvoltages. However, these arresters adopt pure air‑clearance structures and are exposed to atmospheric environments, making them highly affected by altitude and climate factors. Advanced methods now incorporate real‑time lightning monitoring data and environmental parameters to correct dynamic operation curves and enable reliable protection actions.
Several overarching trends are shaping surge arrester technology across all three domains.
Intelligent SPDs equipped with sensing and dynamic regulation mechanisms enable adaptive electrode gap adjustment, achieving protection accuracy of ±0.5 kV and nanosecond‑level response times. Hybrid protection devices combining MOVs, GDTs, and other elements handle both high‑energy lightning strikes and low‑energy switching surges. High‑gradient ZnO chips developed via nano‑powder material modification improve performance while reducing physical footprint.
The global surge arrester market reached approximately USD 2.16 billion in 2025 and is projected to reach USD 3.06 billion by 2034. The DC surge arrester segment specifically is expected to grow from USD 875 million in 2026 to USD 1,642.5 million by 2036, driven by solar PV installations, data centers, and industrial DC networks.
The shift from centralized AC grids toward distributed, DC‑dominant energy architectures demands a corresponding evolution in overvoltage protection. PV systems require SPDs compliant with IEC 61643‑31 that address unique DC arc and insulation fault risks. BESS installations demand heightened protection against thermal runaway, supported by standards such as UL 9540A and emerging guidelines within IEC 60364‑7‑712. DC distribution lines are now served by the newly published IEC 61643‑41:2025, which establishes a comprehensive framework for SPDs in low‑voltage DC systems up to 1,500 V.
