Original price was: 2,500৳ .1,500৳ Current price is: 1,500৳ .
DC Surge Protective Device (SPD) is a safety component that protects electrical equipment from over-voltage surges on DC lines — especially solar PV (photovoltaic) arrays.
When lightning strikes or there’s a sudden spike in voltage, the SPD diverts excess energy to ground so it doesn’t damage your inverter, charge controller, batteries, or other DC equipment.
In solar power systems, DC SPDs are installed between the PV panels and the inverter/charge controller.
DC electrical systems (like solar arrays) are vulnerable to:
Lightning-induced surges
Grid switching surges
Electrostatic discharge
Equipment switching events
Without protection, these surges can:
Damage expensive components (inverter, controller, panels)
Cause premature failure
Create safety hazards
SPDs help limit voltage to a safe level, preserving equipment and improving safety and reliability.
In a typical solar power system with MPPT controller or hybrid inverter:
PV Arrays (DC) → DC SPD → Solar Charge Controller / Hybrid Inverter → Battery Bank
DC SPDs are not installed on the AC side; those require separate AC SPDs.
Rated for direct lightning current
Installed at service entrances or where there’s exposure to direct lightning risk
Higher energy capacity
Use-case: Large commercial systems, rooftop installations with high lightning exposure
Most common in solar PV systems
Protects against indirect surges & switching transients
Installed at PV combiner boxes or at inverter input
Use-case: Residential and commercial solar systems
For point-of-use protection
Lower energy capacity than Type 1 and 2
Used near sensitive equipment
Use-case: Additional local protection (not primary SPD)
When voltage surpasses a threshold:
SPD conducts surge current to ground
Voltage is clamped at a safe level
Once surge ends, SPD returns to normal
Key components inside SPDs:
Metal Oxide Varistors (MOVs)
Transient Voltage Suppression (TVS) diodes
Sometimes gas discharge tubes
| Spec | Meaning |
|---|---|
| Nominal DC Voltage (Un) | System voltage the SPD is meant for (e.g., 24 V / 48 V / 1000 V) |
| Maximum Continuous Operating Voltage (Uc) | Max voltage SPD can withstand continuously |
| Voltage Protection Level (Up) | Voltage level SPD clamps at during a surge |
| Nominal Discharge Current (In) | Surges SPD can handle repeatedly |
| Lightning Impulse Current (Iimp) | Peak current from a lightning surge |
| Response Time | How fast SPD reacts (ns or µs) |
Here’s how to pick an appropriate SPD for a solar DC system:
24 V battery system → SPD rated ≥ 24 V
48 V → SPD rated ≥ 48 V
PV array strings (higher voltage) → SPD rated for ≥ max PV open-circuit voltage (Voc)
Important: Ensure the SPD’s Uc (continuous rating) is higher than your highest expected DC voltage.
