Weidmuller Stringbox 7770019121

Weidmuller Stringbox 7770019121

SKU: 233371

Original price was: €1,454.00.Current price is: €400.00. (21% BTW)

Weidmüller Stringbox 7770019121 – PV Next String Combiner Box (12 strings / 6 MPPT, Fireman Switch)

Picture may differ please look carefully at the type number
The Weidmüller PV Next String Combiner Box 7770019121 bundles up to 12 PV strings on 6 separate MPPTs and safely switches off the DC side via fireman switch (locally as well as remotely). This version is without string fuses and has a replaceable surge protector (SPD) per MPPT.

Datasheet

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Weidmüller Stringbox 7770019121 – PV Next String Combiner Box (12 strings / 6 MPPT, with Fireman Switch)

The Weidmüller PV Next String Combiner Box 7770019121 makes your DC side neat, safe and maintenance-friendly.
This PV Next string box is intended for mounting in the DC connection between PV modules and inverter(s).
It allows you to conveniently combine up to 12 PV strings on 6 electrically separate MPPTs.

Which version is this exactly?

  • Order number: 7770019121
  • Type (according to type overview): PVNCM6I12S1FXV101TXPX10
  • Capacity: maximum 12 strings on 6 MPPTs (2 strings per MPPT)
  • Note: this variant is without string fuses (fuse holders are only on 7770019118 and 7770019119)

Main advantages

  • Fireman switch: contactors can switch off locally and remotely. An activated fireman switch is normally released with a key.
  • DC power contactors per MPPT: the installation can be completely disconnected on the DC side.
  • Overvoltage protection per MPPT: each MPPT has a replaceable SPD (type I/II or type II – depending on version/design).
  • Quick installation: PV connectors at the bottom reduce installation time and make service easy.
  • IP65 enclosure: suitable for protected outdoor use, with transparent polycarbonate cover for quick inspection.

Technical specifications (core)

  • Max. DC input voltage: 1000 V DC
  • Max. current per string input (Inc): 15 A DC
  • Max. current per PV connector: 30 A DC
  • Ambient temperature (operation): -40°C to +40°C
  • Protection rating: IP65
  • Enclosure: GFRP base (glass fibre reinforced polyester) + transparent polycarbonate cover
  • Connectors: WM4C PV connectors, suitable for 4-6 mm²
  • Remote signalling contact (SPD): 24 V / max. 100 mA; 48 V / max. 200 mA
  • Contactor coil voltage: 230 VAC (operating voltage range approx. 195-253 VAC)

Dimensions and mounting

  • Housing (7770019121): approx. 720 (W) × 540 (H) × 202 (D) mm
  • Mounting: wall-mounted, preferably vertically with connectors/cable glands facing downwards
  • Free space: maintain at least 250 mm all round (preferably 400 mm) for cooling and maintenance

Installation tips from practice

  • Protected location: preferably out of direct sun and driving rain (prolonged UV/weather exposure shortens lifespan).
  • Never drill additional holes: IP class remains intact only if the enclosure remains undamaged.
  • Seal unused feedthroughs/connectors: use sealing/blinding materials and protective caps on free PV connectors.
  • Pay attention to polarity & string matching: only connect strings with identical open-clamp voltage together per input to avoid equalisation currents.

Application

This string box is a fine choice for larger residential and business PV systems with multiple MPPTs,
where you want above all: safe switching, surge protection, and a tight, service-friendly DC design.

Safety (short but important)

Preferably work without voltage and follow the correct switch-off sequence: first switch off the inverter, then the DC switch/load breaker,
only then disconnect the strings. DC can be dangerous up to 1000 V – use suitable PPE and always measure without voltage.

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