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Insulation resistance – What is it?

Case Studies

The DC cabling, connectors and solar panels of most Solar PV systems are designed to be isolated from earth.

Where a ‘path to earth’ is created it gives rise to insulation resistance faults and the inverter will shutdown.

What causes it?

In short, it is mainly caused by damaged and poorly installed DC connectors and cabling, and/or faulty solar panels.

A few common examples include:

  • Poor workmanship:
    • DC connectors incorrectly fitted
    • DC cabling and plugs left laying on the roof
  • Rodents eating the DC cable:
    • Rats
    • Pigeons
  • Sharp edge of containment/cable management

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