Definition
A Surge Protection Device (SPD) clamps voltage surges induced by lightning or grid disturbances to protect downstream electronics. Type 1 at service entrance, Type 2 at distribution, Type 3 at sensitive equipment.
SPD Types
| Type | Location | Use |
|---|---|---|
| Type 1 | Service entrance | Withstands direct lightning |
| Type 2 | Combiner / Inverter | Induced surges, branch protection |
| Type 3 | Equipment-specific | Fine protection, sensitive loads |
Key Takeaways
- SPDs protect against voltage surges from lightning and grid disturbances.
- Type 1 (service), Type 2 (distribution/inverter), Type 3 (sensitive equipment).
- Combiner boxes typically include Type 2 SPDs.
- Inverters often have integrated Type 2 SPDs.
- High-lightning regions justify Type 1 at the service entrance.
Frequently Asked Questions
4 commonly searched questions about SPD (Surge Protection Device).
What is an SPD?
Surge Protection Device — diverts surge currents (lightning, grid switching) to ground, protecting downstream electronics. Three types based on location and surge magnitude.
SPD types?
Type 1: service entrance, withstands direct lightning component. Type 2: distribution board / inverter input. Type 3: sensitive equipment, fine protection.
Is SPD required for solar?
Strongly recommended. NEC doesn't strictly require but most modern inverters include integrated Type 2 SPD. Type 1 added at the service for high-lightning regions.
Where to install SPDs?
DC side: in combiner box (Type 2). AC side: at inverter output or main service (Type 1 + 2). Both polarities + ground.
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