DC String Combiner Box 2 Strings 1000V 16A Isolators IP65
DC field combiner box for 2 independent strings (2 IN / 2 OUT) up to 1000 V with isolators, to be installed between the modules and the inverter. For each string it integrates a 32 A fuse holder, a 1000 V DC isolator and an SPD surge protector, with input and output terminal blocks.
IP65 box with 24 DIN modules, components labelled on plastic-coated rails.
The QDC-02/02 SEZ DC field combiner box protects and isolates 2 independent photovoltaic strings up to 1000 V DC. It is installed between the module array and the inverter and performs, for each string, the three DC-side functions: isolating for maintenance, protecting with a fuse holder, and discharging overvoltages to earth before they reach the MPPTs.
Two independent strings, one isolator each
The 2 IN / 2 OUT configuration keeps the two strings separate: two inputs, two outputs, no internal parallel connection. Each string has its own DC isolator, so one string can be isolated for maintenance while the other keeps producing. The SEZ designation refers to these on-board isolators, rated for 1000 V direct current and operable under load: on the DC side, which has no zero crossing, this is the difference between a safe disconnection and an arc that does not extinguish.
QDC-02/02-1000V-16A SEZ technical specifications
| Configuration | 2 strings IN / 2 OUT (independent) |
| Rated voltage | 1000 V DC |
| String protection | 2 fuse holders with 32 A 1000 V DC fuses |
| Isolation | 2 DC isolators 1000 V |
| Overvoltages | 2 SPD surge arresters 1000 V |
| Connections | Input and output terminal blocks |
| Enclosure | IP65 box with 24 DIN modules |
| Weight | 3 kg |
Technical note: the designation states 16 A while the fuse holders are fitted with 32 A 1000 V DC fuses. Confirm the actual rating against the Isc of your modules before ordering.
When to choose the 1000 V 16 A version
The 1000 V ceiling is the standard for modern systems. The two strings can be connected to two separate inverter MPPTs, or paralleled downstream onto a single input: in that case the string fuse becomes active protection and not just back-up. The number of modules in series must be chosen so that the cold Voc stays below the limit of the MPPT and of the isolators. The 16 A rating covers the Isc of standard modules; for high-Isc TOPCon or HJT modules, consider the 25 A version.
Frequently asked questions
Are the two strings paralleled inside the box?
No: they are independent, with two separate inputs and outputs. Any parallel connection is made downstream, towards the inverter. Keeping them separate lets you isolate one string at a time and simplifies fault-finding.
What is the difference from the version without isolators?
The SEZ version integrates the DC isolators that let you isolate each string under load for maintenance. Without isolators, isolation must be provided elsewhere, typically at the inverter input.
Is it suitable for outdoor installation?
The IP65 rating allows it. A position not exposed to the sun all day long is preferable: the internal temperature reduces the service life of the surge arresters.