DC String Combiner Box 1 String 1000V 16A with Isolator IP65
Single-string DC field combiner box (1 IN / 1 OUT) up to 1000 V with isolator, to be installed between the modules and the inverter. It integrates a 32 A 1000 V fuse holder, a 1000 V DC isolator and an SPD surge protector, with input and output terminal blocks.
IP65 box with 8 DIN modules, components labelled on plastic-coated rails.
The QDC-01/01 SEZ DC field combiner box protects and isolates a single photovoltaic string up to 1000 V DC. It is installed between the module array and the inverter and brings together the three DC-side functions: isolating the string for maintenance, protecting it with a fuse holder, and discharging overvoltages to earth before they reach the MPPT.
The isolator (SEZ): why a fuse alone is not enough
The SEZ designation indicates an on-board DC isolator. This is the difference that matters during maintenance: the DC side has no zero crossing, so opening a string under load with an unsuitable device generates an arc that does not extinguish by itself. The built-in isolator is rated for 1000 V direct current and can be operated under load, making it possible to isolate the string safely without shutting down the whole system.
QDC-01/01-1000V-16A SEZ technical specifications
| Configuration | 1 string IN / 1 OUT |
| Rated voltage | 1000 V DC |
| String protection | 1 fuse holder with 32 A 1000 V DC fuse |
| Isolation | 1 DC isolator 1000 V |
| Overvoltages | 1 SPD surge arrester 1000 V |
| Connections | Input and output terminal blocks |
| Enclosure | IP65 box with 8 DIN modules |
| Weight | 4 kg |
Technical note: the designation states 16 A while the fuse holder is fitted with a 32 A 1000 V DC fuse. 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 and leaves room for longer strings: the number of modules in series must be chosen so that the open-circuit voltage (Voc) at the site's minimum temperature stays below the limit of the inverter MPPT and of the isolator. The 16 A rating covers the short-circuit current (Isc) of standard-current modules; for high-Isc TOPCon or HJT modules, consider the 25 A version.
Frequently asked questions
What is the difference from the version without an isolator?
The SEZ version integrates the DC isolator that lets you isolate the string under load for maintenance. Without an isolator, isolation must be provided elsewhere, typically at the inverter input.
Is a string fuse needed on a single string?
On a single string the reverse current is limited and the fuse acts as back-up protection and removable isolation. It becomes essential when several strings are connected in parallel downstream or when the module manufacturer specifies string protection.
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.