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Lockout / Tagout

ACTIVE SOP

Critical Safety Procedure

Failure to properly isolate energy sources is one of the most common causes of electrical injury in solar field work. Read this section completely before working on any electrical components.

PV System Energy Isolation Overview

A solar PV system has multiple energy sources that must each be isolated:

UTILITY GRID (AC)
    ↓ Main AC Disconnect
INVERTER (AC side)
    ↓ DC Disconnect / Array Combiner
SOLAR ARRAY (DC — always energized during daylight)
    ↓ Panel-level (optimizers, Tigo, microinverters)
INDIVIDUAL MODULES

You cannot turn off the sun. The array will produce DC voltage whenever light hits it, regardless of any switch position. Understand this before touching any DC wiring.

Standard PV Isolation Sequence

De-Energizing (Shutdown)

  1. Turn off the inverter via the inverter's shutdown switch or SolarEdge GO / monitoring interface
  2. Open the AC disconnect — main AC breaker or dedicated AC disconnect
  3. Verify AC is de-energized — use your multimeter at the AC output terminals
  4. Open the DC disconnect — array-side or string combiner disconnect
  5. Wait — allow capacitors inside the inverter to discharge (minimum 2–3 minutes for most systems)
  6. Verify DC is de-energized at your work point — measure at the DC input terminals
  7. Apply lockout — lock the disconnect(s) in the open position if work permits
  8. Apply tagout — tag each locked-out point with your name, date, and reason

Re-Energizing (Startup)

Re-energize in reverse order:

  1. Remove all tags and locks (only the person who applied them)
  2. Close DC disconnect
  3. Close AC disconnect
  4. Start inverter per manufacturer procedure
  5. Verify normal operation

DC-Side Special Considerations

DC Wiring Remains Energized

Even with both disconnects open, individual panel connectors (MC4) and combiner box inputs may be energized if modules are receiving light.

Safe practices: - Work on DC wiring only in complete darkness or with panels fully covered - Always verify zero voltage before touching DC conductors — don't assume - Wear electrical-rated gloves rated for the system voltage - Keep one hand away from grounded surfaces when near live conductors

System Voltage Awareness

System Type Typical DC Voltage
Residential string (SolarEdge) 80–600V DC
Residential string (SMA) 200–600V DC
Commercial string 600–1000V DC
With SolarEdge SafeDC Drops to ~1V per optimizer when shut down

Lockout Equipment

Minimum lockout equipment in field kit:

  • Personal safety lock (keyed lock, unique key)
  • Lockout hasp (allows multiple locks on one disconnect)
  • Lockout tags (pre-printed or blank with marker)
  • Lockout bag or station (organized, accessible)

Tagout-Only Situations

If a disconnect cannot be physically locked (no lockout provision on the device):

  • Apply tagout tag to the disconnect
  • Note the limitation in your site report
  • Extra caution required — verify de-energization more frequently
  • Notify lead tech of the tagout-only condition

Group Lockout

When multiple technicians are working on the same system:

  • Each technician applies their own lock to the lockout hasp
  • No one's lock is removed by another person
  • The system cannot be re-energized until all locks are removed by their respective owners