Insulation resistance and failures of a high-power grid-connected photovoltaic installation. A case study

In this article, the authors discuss the crucial aspects of the insulation resistance testing of photovoltaic (PV) installations. This test verifies the integrity of the wiring systems and can be used to detect or prevent damages to wiring as well as ground faults. The insulation resistance test measures the resistance between the ungrounded circuits and the ground under the application of high voltage. The baseline insulation resistance can be compared to measurements over time to assess the degradation of PV arrays or conductors. This test is accepted worldwide as a crucial element of commissioning and acceptance, and it is governed by several technical standards.