Lightning Protection System (LPS)

LPS Components

• Air terminals: rods or finials at high points, positioned using the rolling sphere method so every module row and structural high point falls within the protected zone.
• Down conductors: heavy copper/aluminum cable that carries the strike current from the air terminal to the earth electrode without passing through sensitive PV equipment.
• Earth electrodes: ground rods, plates, or grids sized to dissipate the current into the soil at a resistance the standard allows.
• Bonding: the equipotential bonding that ties racking, frames, conduits, and equipment enclosures to the same reference potential, so a strike current doesn’t create a dangerous voltage difference between metallic parts.

An LPS only addresses the direct-strike hazard. The induced surges that travel down DC strings and AC feeders during a nearby (not direct) strike are a separate failure mode, handled by surge protection devices at the combiner box, inverter, and service entrance — which is why the two are almost always specified together on a solar plant’s electrical drawings rather than as substitutes for one another.

Standards

• IEC 62305-1 (general principles).
• IEC 62305-2 (risk assessment).
• IEC 62305-3 (physical damage protection).
• IEC 62305-4 (electrical systems protection).
• IS 16942 (India national).

Key Takeaways

• LPS protects against direct lightning strikes via air terminals, conductors, and earth.
• Designed per IEC 62305 or IS 16942.
• Combined with SPDs for both direct and induced lightning effects.
• Earth resistance ≤ 10 Ω target.
• Required in high-lightning regions; risk-assessment-driven elsewhere.

Related Reading

LPS decisions rarely happen in isolation from the rest of the electrical and structural package. Where the array racking is being evaluated as part of the down-conductor path, the structural sizing conversation overlaps with how the mounting steel itself is analyzed — see our comparison of SAP2000, STAAD Pro, and manual calculations for solar structures. Earth electrodes for the LPS are typically installed alongside the plant’s main grounding grid during foundation work, which our field guide to pile foundation design for solar ground-mount arrays covers in more detail. And because air terminal placement, down-conductor routing, and earthing layouts all need to show up on the drawing package, they’re documented on the same single-line diagram as the rest of the electrical protection scheme — our guide to solar SLD software and NEC 2023 auto-generation walks through how that documentation comes together.