DC AFCI combiner box 12 in 1 out

The 1500 V DC AFCI combiner box 12 in 1 out, supplied by China manufacturer Zhejiang Soutya New Energy LLC, is a 1500 V DC arc-fault-protected aggregation unit built for utility-scale photovoltaics. Cast from powder-coated, UV-stable aluminium alloy and sealed to IP65, the enclosure withstands coastal salt spray and desert sand storms without corrosion or water ingress. Internally, twelve DC PV fuses give individual string over-current protection, while a thermal-magnetic moulded-case circuit-breaker (MCCB) rated 250 A provides short-circuit and overload isolation. A DC contactor allows remote shutdown from the inverter or SCADA room, and twin Class II SPDs (±/PE) clamp induced lightning surges. An integrated monitoring control unit (MCU) samples each string through twelve Hall-effect current sensors, two voltage sensors and two NTC temperature probes, enabling real-time power comparison, arc-fault detection and rapid-contact opening within 50 ms. All data are exported via an isolated RS485 interface with Modbus-RTU protocol, and a front LED/LCD display gives local alarm codes and string-current histograms. Factory-wired positive, negative and PE busbars maintain dependable grounding continuity, making the box an essential smart-isolation, protection and data-hub for large PV sub-arrays up to 12 × 20 A input.

Wiring Diagram

Application scenarios

Utility-scale PV field – Smart sub-array hub

Plinth-mounted between tracker rows, the box merges twelve 1500 V strings into a single 250 A homerun. Individual PV fuses isolate faulty strings while the mould case circuit breaker provides short-circuit and overload protection; the DC contactor receives a rapid-shutdown signal from the inverter or SCADA, opening the array within 50 ms. Twin SPDs clamp lightning surges on long DC runs and the MCU, fed by 12 Hall CTs, flags arc-fault signatures and imbalance trends via RS485 to the control room, letting maintenance crews pinpoint a failing module before yield drops.

Large commercial rooftop – Multi-MPPT aggregation point

Ballasted on steel trays across expansive flat roofs, the enclosure feeds a central 250 kW inverter. Voltage and temperature sensors track string health; the LCD shows real-time current histograms so facility managers can compare MPPT performance without opening the lid. IP65 aluminium resists 55 °C rooftop heat and driving rain, while the contactor allows remote shutdown for fire-fighter safety during roof interventions.

Agro-voltaic canopy – Elevated tracker combiner

Suspended on pylon beams above crop rows, the unit withstands irrigation mist and ammonia vapours. The MCCB handles in-rush from long cable capacitance when trackers restart at sunrise; temperature sensors inside the box and on the busbar alarm if enclosure heat rise exceeds 20 K, triggering reduced power mode. Arc-fault detection prevents series arcs that could ignite dry foliage, and the sealed aluminium housing keeps dust and insects out of live parts.

Industrial micro-grid yard – DC-coupled storage front-end

Floor-fixed beside battery containers, the combiner aggregates 12 strings into a 1500 V DC bus feeding the PCS charger. Current sensors verify that each string contributes equally to charge cycles; if deviation exceeds 5 % the MCU signals the EMS to equalise or isolate the weak string. The MCCB and contactor provide dual-point isolation for safe battery maintenance, while SPDs protect sensitive IGBT stacks from lightning-induced spikes.