PV distribution board 2-string DC 1000V T1 T2 Mersen Doktorvolt 4494 DV-4494-FOT

Dual-string distribution board for photovoltaic installations

DC-side photovoltaic distribution boards play a key role in every PV installation - this is where the panel strings converge and where the first line of surge protection is installed. Model DV-4494-FOT supports two independent DC circuits, making it a suitable solution for smaller and medium-sized residential or commercial installations based on a dual-string configuration.

The enclosure made of technopolymer provides solid mechanical resistance while being electromagnetically neutral - it does not affect the operation of nearby electronic devices. Dimensions of 215 × 210 × 100 mm (or 215 × 240 × 100 mm after installing PG glands and MC4 connectors) allow for compact surface mounting even in tight technical rooms or near installation risers.

Hermeticity and environmental resistance

The IP65 protection rating means full dust-tight sealing and protection against water jets hitting the enclosure from any direction. This is important in the context of outdoor installations - the distribution board will perform well when mounted on a building facade, at ground level, or in other locations exposed to atmospheric conditions.

The door is made of polycarbonate - a material resistant to impact and UV radiation, which prevents the plastic from becoming brittle due to years of solar exposure. The EPDM rubber gasket maintains flexibility across a wide temperature range, and the stainless steel screws eliminate the risk of thread corrosion during frequent opening of the box for inspections.

T1+T2 class surge protection

The DC circuits are protected by two STPT12-5K1000V-YPV modules - surge arresters from the renowned Mersen brand. The T1+T2 classification (formerly classes B+C) signifies the ability to absorb both high impulse surges originating directly from atmospheric discharges (T1 - Iimp up to 5 kA) and smaller surges generated within the installation (T2 - In up to 20 kA).

The modules operate at a voltage of 1000 V DC, and their maximum operating voltage Uc is 1060 V DC. The maximum current Imax reaches 40 kA, demonstrating a high surge energy absorption capacity. The protection level Up remains below 4.0 kV, effectively limiting surges to safe values for the connected devices.

Mersen modules hold UL and CE certificates and comply with the EN/IEC 61643 standard, confirming their compliance with European safety standards for surge protection devices in photovoltaic installations.

Wiring, connection completeness, and certificates

The distribution board is delivered fully wired - inside you will find:

• H1Z2Z2-K solar cables with a cross-section of 6 mm² (black and red) resistant to weather conditions and UV radiation,
• H07V-K yellow-green grounding conductor with a cross-section of 16 mm² for grounding connections,
• MC4 solar connectors - four female and four male plugs factory-installed on the wires,
• An additional set of four pairs of solar connectors included in the kit.

MC4 connectors operate at a voltage of 1000 V DC, withstand an impulse voltage of 8 kV, and have an IP67 protection rating, allowing them to be used even when temporarily submerged in water.

The manufacturer draws attention to an important safety issue - European standards IEC 62548 and IEC 60364-7-712:2017 prohibit the use of solar connectors from different manufacturers in a single circuit. Improper matching of connectors generates contact resistance, which leads to local temperature increases that can cause a PV installation fire. Therefore, Doktorvolt provides a complete set of customized connectors that match the factory wiring of the distribution board.

Doktorvolt distribution boards are manufactured under a management system c