What is the test?
The purpose of this test is to determine the ability of the PV module to withstand humidity penetration at extreme temperatures. It may be considered as a combination of two other tests - Damp Heat and Thermal Cycling.
Why is this test conducted?
To determine the ability of the module to withstand the effects of High Temperature and Humidity followed by Sub-Zero Temperatures.
How is it conducted?
The Humidity Freeze test as per the IEC 61215 standards, follows the step-wise procedure listed below:
Attach a suitable temperature sensor to the front or back surface of the module(s) near the middle. If more than one module of the same type is tested simultaneously, it will suffice to monitor the temperature of one representative sample.
Install the module(s) at room temperature in the climatic chamber.
Connect the temperature-monitoring equipment to the temperature sensor(s). Connect each module to the appropriate current supply by connecting the positive terminal of the module to the positive terminal of the power supply and the second terminal accordingly. During the humidity freeze test set the continuous current flow to no more than 0.5% of the measured STC peak power current.
Record the module temperature throughout the test, and monitor the current and voltage through the module.
Test Conditions
Temp Range : - 40 ⁰C to +85 ⁰C ±2
Rate of change of temp : <100 ⁰C/h
Dwell time at -40 ⁰C : > 30 mins
Dwell time at +85 ⁰C : > 20 hours
Humidity : 85% ±5% @ +85 ⁰C
No. of cycles : 10
Cycle time : 24 hrs for each cycle
Defects noticed in a module that fails this test:
Delamination of Encapsulant and Backsheet
Backsheet Cracking
Failure in edge sealing
Corrosion at the front surface interconnects
Image Credits: RenewSys