PV DC distribution board 1000V T1 T2 Mersen Doktorvolt 4418 DV-4418-FOT

Comprehensive photovoltaic installation protection

The Doktorvolt photovoltaic distribution box is a single-circuit solution dedicated to small and medium-sized PV installations. The device has been designed for the safe connection of strings to the inverter - it is equipped with high-quality components protecting against both surges and the effects of potential short circuits.

Enclosure and operating conditions

The enclosure made of technopolymer is characterized by high resistance to atmospheric conditions - it does not corrode, requires no maintenance, and maintains its mechanical properties through years of UV radiation exposure. Dimensions of 142 × 210 × 100 mm (with glands and connectors: 142 × 240 × 100 mm) allow for surface mounting even in places with limited space. The IP65 protection rating ensures full sealing - dust will not enter the interior, and a stream of water sprayed on the enclosure from any direction will not damage the components.

The door is made of polycarbonate - a transparent material, allowing the state of the distribution box to be seen without opening it. The EPDM rubber seal maintains flexibility even at negative temperatures, and the stainless steel screws guarantee the durability of mechanical connections. The enclosure color is classic grey RAL 7035, which blends well with building facades.

Surge protection and electrical components

The heart of the distribution box is the Mersen STPT12-5K1000V-YPV surge protective device - one of the most recognizable manufacturers of protective elements in the world. The device operates at a maximum voltage of 1000V DC (continuous voltage Uc is 1060V DC), allowing for its use in standard photovoltaic installations.

The T1+T2 protection class means two-stage detection and quenching of surges:

• T1 (class B) - impulse current Iimp up to 5 kA, ability to absorb energy generated by direct lightning strikes,
• T2 (class C) - test current In 20 kA, maximum current Imax 40 kA, effective protection against indirect atmospheric surges and switching surges.

The protection voltage level Up is 4.0 kV, which effectively reduces the amplitude of pulses reaching the inverter input. The surge protector manufacturer - Mersen - holds UL and CE certificates, and the product itself complies with the EN/IEC 61643 standard.

Internal wiring consists of 1×6 mm² solar cables (black and red) with a rated voltage of 0.6/1 kV. The core cross-section was selected so that power losses over the length of the distribution box are minimal even at full string load.

Solar connectors and kit contents

A set of connections is factory-installed:

• PG-11 cable gland - string entry from the module side,
• MC4 solar connectors - factory-installed (2x female + 2x male) enabling quick connection to the inverter.

The kit also includes an additional set of solar connectors (2x female + 4x male) intended for creating expansion or emergency connections. This is an important addition - European standards IEC 62548 and IEC 60364-7-712:2017 prohibit mixing connectors from different manufacturers in a single DC circuit due to the risk of contact resistance leading to overheating of connections. Using only consistent components is the foundation of the safety of the entire installation.

Solar connectors operate at a voltage of 1000 V DC, withstand an impulse voltage of 8 kV, and have an IP67 protection rating.

Standards, certificates, and production

The manufacturer has implemented a quality management system certified by TÜV SÜD, which confirms the repeatability of production processes and quality control at every stage. The distribution box has a CE declaration of conformity, complies with the EU RoHS directiv