DAMP HEAT TESTING FOR SOLAR MODULES

The PV Damp Heat Test is an accelerated environmental aging test

that determines the ability of the solar module to withstand long-term exposure to high temperature and penetration of humidity.

Test Method

The damp heat test is performed by applying 85cal +- 2cal with a relative humidity of 85% for an uninterrupted cycle of 1,000 hours, which is well over 1 month. 1,000 hours of damp heat testing at 85cal and relative humidity of 85% equates to multiple years of outdoor exposure. The panel to be tested is placed in a damp heat test chamber in which the panel is exposed to these conditions.

Defects can occur during Damp Heat Testing

This test particularly challenges the lamination process of the PV module and the edge sealing from humidity. The peel strength of the PV modules that are laminated according to the traditional lamination process is decisive.
This test can detect issues related to the lamination process and the edge sealing of the solar module. Delamination and corrosion of different cell parts can be detected as a result of penetration of humidity.
Damp heat testing can reveal various defects, such as

delamination, deterioration of glass surface (AR coating), frame corrosion, metal grid discoloration and junction box attachment and connection failures.

Damp Heat Testing and IEC 61215

The Damp Heat test is an

environmental quality test

and one of the qualifying tests for IEC 61215. The Damp Heat test is carried out before Mechanical Load testing and Wet leakage current test is performed before and after the test.
Even if no major defects are detected after DH1000 (Damp Heat testing for 1000 hrs), the module is then stressed to the point that it becomes more fragile for the subsequent

mechanical load testing.