PV distribution board 2-String DC 1000V T2 Phoenix Contact Doktorvolt 4456 DV-4456-FOT

Dual protection for photovoltaic strings

The Doktorvolt PV combiner box is used to receive and protect two strings on the DC side of a photovoltaic installation. It is designed to work with crystalline modules in systems with an operating voltage of up to 1000 V DC, making it an appropriate choice for both smaller residential installations and medium-sized commercial facilities.

Surge protection and components

Surge protection is provided by two Phoenix Contact VAL-MS 1000DC-PV/2+V surge arresters - T2 class devices, which means they are capable of absorbing impulse surges with a test current of 15 kA and a peak value of up to 40 kA. The voltage protection level Up < 3.7 kV effectively reduces the risk of PV module damage during atmospheric discharges near the installation.

The maximum operating voltage is 1170 V DC, so the combiner box has a margin relative to typical string configurations - it can be used even when modules operate at elevated temperatures (voltage increases as cell temperature decreases).

Enclosure and operating conditions

The enclosure, made of technopolymer, is characterized by resistance to UV radiation and harsh weather conditions - rain, dust, and extreme temperatures. The IP65 protection rating ensures full dust tightness and protection against water jets from any direction.

The enclosure dimensions are 215 × 210 × 100 mm (with installed PG cable glands and MC4 connectors, the width increases to 240 mm). The gray color RAL 7035 is a standard for electrical combiner boxes - neutral and easy to keep clean on a facade or roof.

The EPDM rubber gasket, stainless steel screws, and polycarbonate door create a durable construction for many years of outdoor operation without the need for maintenance.

Wiring and solar connectors

The combiner box is factory-wired with BiT BiT 1000 solar cables with a cross-section of 6 mm² - black and red for the DC poles, and a yellow-green H07V-K 16 mm² protective conductor. Such a selected cross-section minimizes power losses on long cable routes from the strings to the inverter.

A set of 8 MC4 connectors (4× female + 4× male) is included with the combiner box - a sufficient set to connect two strings plus a reserve. This is practically important: European standards IEC 62548 and IEC 60364-7-712:2017 prohibit mixing connectors from different manufacturers due to the risk of contact resistance and overheating of connections, which can lead to a PV installation fire.

The MC4 connectors have an IP67 protection rating, an operating voltage of 1000 V DC, and withstand an impulse voltage of 8 kV.

Certificates and manufacturer quality

The manufacturer - Doktorvolt - has implemented a quality management system certified by TÜV SÜD according to the ISO 9001:2015 standard. The surge arresters hold a certificate of conformity with the EN50539-11 standard, and the entire combiner box meets the requirements of CE directives, the EU RoHS directive, and the IEC61439 construction standard.