AS/NZS Solar Safety
A single SPD rarely provides complete protection on its own — coordination between multiple devices is the real design goal.
Surge protection devices (SPDs) protect solar and general electrical installations from lightning-induced transients and switching surges — but a single SPD rarely provides complete protection on its own. Coordination between multiple devices at different points in the system is the actual design goal.
| Location | Typical role |
|---|---|
| Main switchboard | First line of defense, handling the bulk of a major transient before it propagates further into the installation |
| DC combiner box or array junction | Protects the DC circuit specifically, which is otherwise directly exposed to induced transients from a nearby strike |
| Inverter input/output | Fine-grained final protection at the most sensitive electronic equipment |
An SPD closer to the source of a major transient absorbs the bulk of the energy, letting the downstream SPD handle only the residual, smaller transient it wasn't designed to fully absorb on its own. Installing only a single SPD at one point in the system — without this layered coordination — can leave that device overwhelmed by a large event it wasn't sized to handle alone.
See how OhmWorks' solar-related calculators account for protection device requirements in the AS/NZS PV/Solar DC Cable Sizing calculator.
Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks