System grounding scheme

Choosing how the system is grounded, together with offset strategies, is one way to reduce the voltage stress behind Potential Induced Degradation (PID). Field assessments record the grounding of the substructure and module frames, and whether the positive or negative conductor is grounded or left ungrounded. All exposed metal parts that carry no current, such as module brackets and inverter enclosures, should be grounded. Where a site has several inverters, bond their grounding points and the array frames to a shared equipotential conductor. An inverter that runs an ungrounded PV array still needs equipment grounding. For frame grounding, a tin-plated lay-in lug fitted with a toothed washer against the aluminium frame held up best in salt mist. Anti-oxidant compound between lug and frame lengthened time to failure. Grounding connections installed without measuring torque failed 5 times faster than connections tightened with a torque wrench. Inspect and test ground connections and grid continuity regularly as part of electrical maintenance. If an inverter reports a missing grounding connection, check that the grounding conductor is connected correctly. Grounding faults can also cause an inverter to fail completely, so a good ground matters for more than PID.

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• sentence 8: support check: partial - Passage says complete inverter failure can result from grounding-related faults, but the 'more than PID' comparison is not stated in it. -->