Lightning & Surge Protection for Tiny DC Systems

Even a 10 W panel deserves respect when the sky gets angry.

1) Fuses and Breakers

• Fuse every battery lead within 20 cm of terminal.
• Match fuse type to wire gauge (AWG chart never lies).

2) Transient Voltage Suppressors (TVS)

• Place a 5.0 V TVS across the lock's input rails.
• 12 V side: 18 V TVS near buck converter.

3) Bonding & Ground

• Common bond for panel frame, battery negative and door hardware.
• If metal structure exists, tie to earth rod (~2 m copper).

4) Cable Management

• Twist positive/negative pairs — reduces induced spikes.
• Keep solar leads and signal lines separate.

Related Reading

• Solar-Powered Smart Lock Kit — Fusing and wiring best practices.
• Cable Runs & Conduit — Cable management and bonding.
• Door Materials & Mounting — Electrical bonding for metal doors.