First Solar Combiner Box Fused Wiring Harness 10 Strings MC3 12 AWG RHW-2 600V

First Solar Combiner Box Fused Wiring Harness 10 Strings MC3 12 AWG RHW-2 600V

This is a purpose-built fused solar PV combiner box and wiring harness designed for use with First Solar thin-film panels in a ten-string, five-panels-per-string configuration. The outdoor-rated gray plastic enclosure houses a DIN rail with eleven Ferraz Shawmut ULTRASAFE fuse holders that protect each string individually and the common output. All wiring is 12 AWG RHW-2/USE-2 cable rated for outdoor, UV-exposed installation at up to 600 volts. MC3 connectors are used throughout for direct connection to First Solar panel leads.

Specifications & What's Included

• Enclosure: outdoor-rated plastic, 15 × 17 × 6 inches
• DIN rail with 11 Ferraz Shawmut ULTRASAFE fuse holders installed
• Fuse holder ratings: 800V / 30A UL; 690V / 32A IEC
• Common fuse holder: Littelfuse KLKD 20 — 20A fast-acting, 600V DC/AC
• String fuse holders (×10): Littelfuse KLKD 2 — 2A fast-acting, 600V DC/AC
• One common output wire (20A fused) serving all ten strings
• Ten individual string wires labeled #1 through #10, each to the positive side of one string
• Wire: 12 AWG type RHW-2 / USE-2, 600V rated, UV-resistant, sunlight-resistant
• Connectors: MC3 (compatible with First Solar panel leads)
• String voltage range: 300–500V (five First Solar panels in series produce approximately 338V)
• Intended for 10 strings × 5 panels per string = 50 panels total

Applications

Solar PV combiner boxes aggregate the output of multiple panel strings into a single combined DC output before feeding an inverter or charge controller. This unit was specifically designed for First Solar thin-film PV arrays, where five panels wired in series produce a string voltage in the 300–500V range. The individual per-string fusing (2A per string) provides overcurrent protection at each source circuit, which is required by the NEC for PV systems where multiple strings are paralleled. The 20A common fuse protects the combined output feed. The RHW-2/USE-2 cable designation is important for outdoor solar installations: these cable types are rated for direct sunlight exposure and resist UV degradation over time, making them appropriate for rooftop or ground-mount arrays where wiring runs are exposed to the elements. Combiner boxes of this type are a standard part of residential and commercial PV array balance-of-system (BOS) equipment.