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Why does my SolarEdge inverter show an isolation fault in the morning?

Short answer

At each start-up, a SolarEdge inverter checks the insulation between the panels' wiring and earth. It trips if the reading falls below 600 kΩ on single-phase models or 1 MΩ on three-phase models. Morning dew can cause the fault, and it can clear once the array dries. If it keeps returning, a PV installer should test each string.

Last checked 24 September 2026 · 1 source

In more detail

  • Codes: 2x19 / 18x86 (single phase), 8x58 (three phase).
  • SolarEdge warns the fault can disappear and recur, so troubleshoot soon after it appears.
  • Homeowner: note the times and weather; don't touch DC cables or the DC isolator.
  • Installer: insulation-resistance test per string, check connectors, cable damage and water in isolators.

The facts, dated

  1. 01
    Isolation trip threshold, single-phase SolarEdge inverters — 600 kOhm

    manufacturer · UK · checked 24 September 2026 · SolarEdge

  2. 02
    Isolation trip threshold, three-phase SolarEdge inverters — 1 MOhm

    manufacturer · UK · checked 24 September 2026 · SolarEdge

Sources

Last checked: 24 September 2026