Busbar and gPV Fuse Coordination: NEUTRON Scope at the Haden 2 GW Solar Plant

1. Why busbar sizing matters at 2 GW

Haden is a roughly 2 GW solar plant in Saudi Arabia, large enough that the internal busbar and fuse coordination of every combiner box becomes a plant-wide reliability factor. Each combiner aggregates the continuous current of many strings. If the internal busbar and terminals are not rated for the summed current including bifacial gain, the box becomes the weak link of a 2 GW plant.

2. NEUTRON combiner scope

• PV combiner boxes rated to 1500 V DC with individual gPV fuse protection per string.
• Internal busbar and terminal block rated against summed continuous current.
• DC disconnect and Type 2 DC SPD staged to the 1500 V envelope.
• Monitored output for string-level current visibility.

3. gPV fuse coordination

Each string fuse is sized to 1.25x the module short-circuit current including rear-side gain, and coordinated with the downstream device so a fault clears at the nearest point. This selectivity was verified before release.

4. Environmental specification

• Current parts derated for sustained desert heat.
• Enclosure to IP65 with a corrosion class for inland dust.
• Ventilation path validated for the protection devices.

5. Outcome

Correct busbar and fuse coordination gave the plant a robust combiner foundation. The lesson is that at gigawatt scale the combiner box internals deserve the same engineering attention as the substation.