Surge Protector Devices

Lightning and switching surges can destroy charge controllers, inverters and alternator diodes in a fraction of a second. A surge protector device (SPD) diverts the spike safely to ground. This collection includes MidNite Solar MNSPD surge protectors for 115V and 300V AC, 600V AC and 300V DC lines, the AERL Surge Buster lightning arrestor, AERL ground fault interruption, and the Sterling 12-24V alternator surge protector AP12D.

How to choose a surge protector

• Circuit type: pick DC models for solar arrays and AC models for inverter or shore power lines.
• Voltage rating: the SPD rating must sit above the normal maximum voltage of the circuit.
• Location: fit protection at both ends of long cable runs, such as an array far from the controller.
• Alternators: a surge protector guards diodes if the battery is switched off while the engine runs.

Do solar panels on a boat need surge protection?

Long PV runs and masts attract induced surges. A DC SPD near the charge controller is an inexpensive safeguard; see PV combiner boxes for a tidy place to mount it.

What does the AP12D do?

It protects the alternator from voltage spikes caused by disconnecting batteries while charging. See alternator accessories.

Plugged into shore power? A galvanic isolator for your boat blocks the stray DC currents that corrode underwater metals.