Wet Leakage Current Testing for Solar Modules
Author: Steve Fairless
Date Published: 20th February 2024
Understanding the Wet Leakage Current Test
The wet leakage current test is a crucial electrical assessment conducted by manufacturers of various electrical devices. It measures the electrical isolation of a device's casing to ensure that it can resist moisture or wet conditions typical of outdoor environments.
Conducting the Wet Leakage Current Test
During the test, the unit is placed in a shallow pool so that the entire surface of the unit is submerged, with the exception of cable ports or MC4 connectors of junction boxes that are not meant to be water-resistant (lower than IPX7 rating). A specific testing voltage is applied between the output connectors - which are interconnected - and the solution in the bath. This voltage, increased to the unit's highest system voltage, is sustained for two minutes. For units exceeding 0.1 m2, the insulation resistance should not fall below 40 MΩ per square metre.
The Importance of Wet Leakage Current Testing for PV Modules
This testing procedure is crucial for evaluating a solar module's insulation effectiveness against moisture entry in the wet conditions where the PV system operates, like rain, dew, fog, or thawing snow. These conditions can lead to moisture seeping into the system, causing corrosion, ground faults, and risks of electric shocks.
Common Causes for Failure in Wet Leakage Current Tests for PV Modules
Among the various tests for PV module evaluation in labs, the wet leakage current test has one of the highest failure rates. Aside from connector issues, failures typically arise from post-humidity freeze tests or Damp Heat tests, indicating potential deficiencies in lamination or edge-sealing processes during the manufacturing stage.
Wet Leakage Current Testing in Relation to IEC 61215 Standards
The Wet Leakage Current test is essential for electrical safety and a critical compliance test for the IEC 61215 standards. This test is performed after the insulation test and reiterated at the end of the quality control sequence, ensuring all other tests have been satisfactorily passed.
