DC Field Box 8 Strings 1000V with Fuses

The Icierre QDC-08/08-1000V-16A-SEZ is a DC field box for eight independent PV strings. For each string it integrates a 1000 V disconnector, a fuse holder with a 16 or 20 A gPV fuse and a 1000 V surge arrester, with input and output terminal blocks in an IP65 enclosure with 96 modules. It is sized for commercial plants and large residential arrays with multi-input inverters.

Eight inputs, eight outputs: a box to match to the inverter

The 8 IN / 8 OUT configuration keeps every string separate up to the inverter. It makes sense when the inverter has eight string inputs, for example four MPPT trackers with two strings each, and each string needs to be isolated and protected individually. Before ordering, count the inverter inputs and check how they are grouped on the MPPTs: that grouping tells you whether string fuses are essential or an additional protection.

With eight strings the maintenance advantage is clear. Opening a single disconnector isolates one string for open-circuit voltage, current or I-V curve measurement, while the other seven keep producing. On an array of this size, locating a faulty module or connector becomes a matter of minutes per string, not a plant shutdown.

QDC-08/08-1000V-16A-SEZ features

Three design checks before ordering

Voltage. The limit is 1000 V: the open-circuit voltage of each string at the site's minimum temperature must stay below it, even if the inverter accepts 1100 V.

Current and fuses. The 16/20 A fuses must be compared with the module short-circuit current and with the maximum series fuse rating in the module datasheet. With large-format modules above 14-15 A, the rating must be recalculated.

Surge arrester position. The box SPDs protect the array side. If the box is far from the inverter, the designer assesses whether surge protection is also needed where the cables arrive at the inverter, based on the lightning risk assessment of the installation.

Frequently asked questions

Is the QDC-08/08 available from stock?

The supplier lists it as made to order. Lead time should therefore be checked when ordering, which is also the right moment to confirm the fuse rating based on the modules actually installed.

Which inverters is an eight-string box used with?

With inverters that have eight string inputs, typically three-phase commercial models with several MPPT trackers. The eight separate outputs connect one by one to the inverter inputs, keeping every string traceable.

Are fuses really needed if strings stay separate?

It depends on how many strings the inverter parallels on the same MPPT. With several strings in parallel, a fault lets the others push reverse current into the faulty string: the fuse interrupts it. The check compares the possible reverse current with the value the module can withstand.

How does it differ from a combiner box?

A combiner joins several strings onto a single output towards the inverter; this box keeps eight separate outputs. They are different, non-interchangeable products: choosing the wrong one means rewiring the DC side.

How is a DC field box maintained?

Periodically check surge arrester status indicators, terminal tightness and fuse condition, always after opening the disconnector of the string concerned. A blown fuse should be replaced only after finding the cause, with a gPV DC fuse rated at least 1000 V.