DC Box 5 PV Strings 1000V Icierre QDC
Icierre QDC-05/05-1000V-16A-INT: DC combiner and protection box for 5 photovoltaic strings, with 5 isolator switches rated 1000 V 16 A, 5 surge arresters and numbered input and output terminal blocks.
5 IN / 5 OUT configuration: the strings stay separate all the way to the inverter, with no paralleling. Pre-wired enclosure. To check before ordering: string voltage within 1000 V and module Isc within 16 A.
The Icierre QDC-05/05-1000V-16A-INT is a DC combiner and protection box for photovoltaic systems with five strings: five 1000 V isolator switches, five surge arresters and numbered input and output terminal blocks, all pre-wired in a single enclosure.
Five inputs and five outputs: the strings stay separate
This is what the "05/05" code declares, and it needs to be understood before ordering. This box does not parallel the strings: each one enters, is isolated and protected, and leaves keeping its own identity all the way to the inverter. That is the correct configuration when the inverter has several MPP trackers and you want each string — or each pair — working on its own, which is essential when roof faces have different orientations.
A true combiner, which merges several strings onto a single pair of conductors, has a different code and function and requires string fuses sized for reverse current. Confusing the two at design stage means rewiring on site.
Why the DC side needs isolation
A PV array is live whenever there is daylight: it cannot be switched off and there is no upstream supply to remove. One isolator per string allows you to isolate a single string for maintenance, fault finding or measurement without shutting down the whole system — and without unplugging MC4 connectors under load, which is exactly how DC arcs start.
The surge arresters complete the protection on the most exposed part of the installation: modules cover hundreds of square metres and act as an ideal antenna for surges induced by nearby lightning, the most common cause of inverter input failure.
Features
| Part number | QDC-05/05-1000V-16A-INT |
| Configuration | 5 strings in, 5 out (no paralleling) |
| Isolation | 5 isolator switches, 1000 V, 16 A |
| Surge protection | 5 arresters, 1000 V, one per string |
| Connections | Numbered input and output terminal blocks |
| Maximum system voltage | 1000 V DC |
| Supply | Pre-wired and assembled enclosure |
| Manufacturer | Icierre |
Two checks to run before ordering
Voltage. The box is rated 1000 V, while many recent string inverters accept up to 1100 V and are designed around that margin. The string's open-circuit voltage, corrected to the minimum design temperature, must not exceed 1000 V: a string sized for an 1100 V inverter may be out of range for this box.
Current. The isolators are rated 16 A. That suits traditional PERC modules, but large-format TOPCon and HJT modules exceed 15 A of short-circuit current and in some cases reach 17-18 A. With those modules the margin is nil or negative: check the Isc of the module actually installed, not the nameplate power. That check decides whether this is the right box or whether a larger size is needed.
When a DC box is actually needed
On a domestic system with two or three strings and an inverter that already has a built-in DC isolator, an external box often adds nothing. It becomes the right choice when there are many strings, when the array is far from the inverter, when maintenance has to be possible on separate sections, or when DC-side surge protection is not already provided elsewhere. Five strings is the size of a small to medium commercial system, or of a large residential array spread over several roof faces.
Frequently asked questions
Does this box parallel the strings?
No. It has five independent inputs and five outputs: each string keeps its own path to the inverter. If several strings need to be merged onto one input, a combiner box is required — a different product, with string fuses.
Is it suitable for TOPCon modules at 15-16 A?
It must be checked case by case. The isolators are rated 16 A: with modules whose short-circuit current approaches or exceeds that figure the margin is insufficient. The figure to compare is the module's Isc at standard test conditions, uprated as design rules require — not the current at maximum power point.
Is it needed if the inverter already has a DC isolator?
It depends on the system. The isolator built into the inverter opens all inputs together; this box lets you isolate a single string while the others keep producing, which makes a real difference on a large array. It also adds per-string surge protection, which the inverter does not always provide.
Can it be installed outdoors?
Boxes in this range are built for field installation, but the enclosure's protection rating should be verified on the specific configuration supplied. In any case a position sheltered from direct sunlight is preferable: accumulated heat stresses arresters and isolators, the very components the DC-side safety rests on.
Do surge arresters need replacing over time?
Yes. SPDs are sacrificial components: after absorbing one or more significant surges the cartridge is spent and the status indicator shows it. Checking that indicator belongs in the system's periodic inspections — a spent arrester no longer protects and does not announce it.