Humidity, Temperature, and Voltage: Task Group 3
Task Group 3 is focused on testing for humidity, temperature, and voltage stresses.
The ingress of moisture with or without electrical bias has been shown to cause corrosion and charge movement in PV modules. Temperature and humidity have been used as accelerated stress tests for PV modules for many years. There are multiple humidity and humidity/electrical bias degradation modes with widely varying acceleration factors. The group's development of true accelerated lifetime tests must take variation of environmental conditions into account.
Task Group 3 has focused on developing tests that can accelerate delamination of encapsulants leading to moisture ingress and subsequent corrosion. Group 3 is collaborating with Task Group 5 (UV, temperature, and humidity) to evaluate the impact of UV exposure on the adhesion of encapsulant materials to glass. Based on these results and other studies, a draft proposal for a test sequence has been developed and was published at the 40th IEEE PVSC (see below).
Group 3 has also been supporting the effort underway in IEC TC82 to develop standard test methods for measuring Potential Induced Degradation (PID). Two standard test methods are being proposed, one in a damp heat chamber and one using aluminum foil. These methods can be utilized by the PV industry to characterize the susceptibility of PV products to PID. Once PID is well understood, a PID Qualification Test will be developed probably as a part of the PV Module Qualification Test.
Group 3 continues to assess the performance of field-aged modules. The group is collecting performance data from modules with more than 10 years of exposure in hot humid climates in an effort to identify humidity-related failure and degradation modes.
IEC 62892-1 "Comparative testing of PV modules to differentiate performance in multiple climates and applications—Part 1: Overall test sequence and method of communication," is being developed by IEC Technical Committee 82. The first committee draft is being reviewed. The general concept being proposed for inclusion in the IEC Comparative Testing Standard was presented at the SOPHIA workshop and at the 40th IEEE PVSC:
Wohlgemuth, J. S. Kurtz, T. Sample, M. Kondo, and M. Yamamichi "Development of Comparative Tests of PV Modules by the International PV QA Task Force." IEEE PVSC, Denver, CO. June 2014.
John Wohlgemuth — National Renewable Energy Laboratory, representing the Americas
Neelkanth Dhere — Florida Solar Energy Center, representing the Americas
Takuya Doi — National Institute of Advanced Industrial Science and Technology, representing Japan
Tony Tang — Canadian Solar, representing China
Volunteers representing other parts of the world are welcomed.