For effective surge protection, surge protective devices (SPDs) with integrated metal oxide varistors (MOVs) must be closely matched to the PV system’s maximum continuous operating voltage. Using an over-rated SPD (e.g., 1,000 V or 1,500 V) in a 600–800 V system can delay response time during surges, reducing protection efficiency and potentially exposing sensitive components to damage. 

To address this DC-side safety concern, SPD manufacturer CITEL is set to unveil its latest DPVN series SPDs, featuring a lower maximum continuous voltage (Ucpv), at the event. According to the company, the new devices are designed for continuous DC system voltages between 600 V and 850 V – ideal for rooftop and ground-mounted PV systems operating below the traditional 1,000 V or 1,500 V range. The DPVN series will be available in both Type 1+2+3 and Type 2+3 versions. 

The company says these devices stand out in 2 key areas: enhanced safety and an extended operational lifespan. 

Enhanced Safety 

During surge or overvoltage events (e.g., from lightning or switching operations), CITEL’s latest SPDs with lower maximum continuous voltage ratings enhance plant safety, particularly for systems with lower operating voltages. By adjusting the tripping threshold to align with these lower voltages, the SPDs activate their integrated MOVs well below traditional threshold voltages, providing faster and more reliable protection on the DC side. 

This advancement ensures that sensitive components are safeguarded by quickly diverting harmful surge currents to ground through the MOVs. However, to prevent safety hazards such as fire, equipment damage, or SPD failure resulting from overheated or degraded MOVs, CITEL has integrated its patented Central Thermal Control (CTC) disconnection technology. 

This thermal disconnection system is essential for safely disconnecting active MOVs from the circuit under excessive thermal stress. It prevents MOV overheating and long-term degradation, while also reducing the risk of thermal runaway – a condition in which a failing MOV may enter a short-circuit state. According to CITEL, the patented CTC design places a single thermosensitive disconnection point at the center of the MOV array, ensuring equally short fuse paths for all connected MOVs. This enables quicker heat detection and faster disconnection. 

Lars Strzeletz, CITEL's Marketing Director, stated: “From now on, even PV systems with lower operating voltages can benefit from our patented disconnection technology. Thanks to its special design, it triggers much more sensitively, which increases safety.” 

Extended Operational Lifecycle 

To extend the operational lifespan of SPDs, CITEL integrates its patented VG technology, which helps prevent the premature aging of the connected MOVs. 

Lars Strzeletz commented, “We are confident in the long service life of our arresters. That’s why we offer a ten-year warranty on all surge arresters equipped with VG technology.”