PV DC 1000V T1 T2 2-string MC4 distribution board Solarna Doktorvolt 4555 DV-4555-FOT

Two-string photovoltaic combiner box for PV installations

The Doktorvolt brand DC combiner box is designed to secure and protect photovoltaic installations from the effects of surges. The design supports two strings (DC circuits), making it an appropriate choice for small and medium-sized PV systems - both in residential buildings and commercial facilities. The device operates at a rated voltage of 1000V DC, and the maximum operating voltage Uc is 1050V DC.

Enclosure and operating conditions

The enclosure is made of polycarbonate - a material valued for its resistance to weather conditions, which is important when mounting outdoors. The gray RAL 7035 color allows for discreet installation of the combiner box on a facade or near the PV installation.

The IP65 protection rating means full dust tightness and resistance to water jets - therefore, the combiner box will perform well in outdoor conditions without additional shielding.

The enclosure dimensions are 238 × 200 × 111 mm (with M F4 connectors: 265 × 200 × 111 mm), and the mounting is surface-mounted - on the surface of a wall or support structure. The gasket made of EPDM rubber maintains flexibility across a wide temperature range, and the stainless steel screws do not corrode even with long-term exposure to moisture.

Surge protection and components

Surge protection is provided by two Phoenix Contact VAL-MS-T1/T2 surge arresters - from one of the most recognized manufacturers of electrotechnical components on the market. The T1 T2 protection class ensures the ability to absorb both high lightning impulses and smaller operating surges. The test current In is 15 kA, and the maximum current Imax is 40 kA.

The voltage protection level Up below 3.5 kV effectively reduces surges to values safe for the connected PV modules and inverter. The arresters comply with the IEC 61643-11:2011 standard, and the entire combiner box complies with the requirements of European standards regarding photovoltaic installations.

Wiring and solar connectors

The interior of the combiner box is equipped with internal wiring - a H07V-K 16 mm² yellow-green protective conductor as a protective conductor and a 6 mm² solar wire in red insulation for the DC poles.

A complete set of MC4 solar connectors is included with the combiner box - four female and male plugs. An additional connection set ensures readiness for connection without the need to purchase connectors separately. The solar connectors operate at a voltage of 1000 V AC/DC, withstand an impulse voltage of 8 kV, and have an IP67 protection rating, allowing them to be used even in places exposed to direct contact with water.

Production takes place in a management system certified by TÜV SÜD, and each unit has an individual certificate confirming compliance with IEC standards and quality of workmanship.