Specific Degradation Risks

Certain materials and material combinations in the module show an increased incidence of specific degradation effects and performance losses (e.g., snail trails, PID, capacitive effects). With our customized test programs, we can specifically address and evaluate these risks.

 

PID (Potential Induced Degradation)

Potential-induced degradation (PID) is a failure which leads to severe, partially irreversible power losses in the field. In a PID test, we check the sensitivity of the modules with respect to electrical potential differences between cells and frame/glass according to the current state of science and research.

 

UV-induced Degradation

The UV test is carried out as part of the module certification as a preconditioning test with a UV dose of 15 kWh / m².

 

Snail tracks

On solar cells with microcracks discoloration of the metallization may appear, which look like snail tracks. The discolorations are triggered by various chemical mechanisms that Fraunhofer ISE has investigated in a study. Whether these optical features with long-term consequences, e.g. delamination are related to the affected modules is currently under review.

Using innovative and state-of-the-art analysis methods, we systematically examine the defect in the TestLab PV Modules. We investigate the following:

• which components are responsible for snail tracks?
• how does the degradation of the modules develop - are long-term damages to be expected?

We test the long-term effects using accelerated aging tests in the TestLab PV Modules. In addition, we examine new materials and combinations of materials for their vulnerability to snail tracks.

 

LeTID (Light and elevated Temperature Induced Degradation)

In particular, PV modules with rear passivated cells of the so-called PERC technology can be affected by "Light and Elevated Temperature Induced Degradation" (LeTID). In contrast to light-induced degradation (LID), these modules run the risk of slow but massive power degradation, which can fully or partially regenerate over the long term. We develop test methods to investigate LeTID effects on PV modules.Since certain defect mechanisms are evidently induced by UV radiation, a UV test with a higher UV dose can help to identify the risk for these defects.