Executive summary

One key factor of reducing the costs of photovoltaic systems is to increase the
reliability and the service life time of the PV modules. Today’s statistics show
degradation rates of the rated power for crystalline silicon PV modules of 0.8%/year
[Jordan11]. To increase the reliability and the service life of PV modules one has to
understand the challenges involved. For this reason, the international Task 13 expert
team has summarized the literature as well as their knowledge and personal
experiences on actual failures of PV modules.
The target audience of this work is PV module designers, PV industry, engineering
lines, test equipment developers, testing companies, technological research
laboratories, standardisation committees, as well as national and regional planning
authorities.
In the first part, this document reports on the measurement methods which allow the
identification and analysis of PV module failures. Currently, a great number of
methods are available to characterise PV module failures outdoors and in labs. As
well as using I-V characteristics as a diagnostic tool, we explain image based
methods and visual inspection. For each method we explain the basis, indicate
current best practice, and explain how to interpret the images. Three thermography
methods are explained: thermography under steady state conditions, pulse
thermography and lock-in thermography. The most commonly used of these
methods is thermography under steady state conditions. Furthermore
electroluminescence methods have become an increasingly popular standard lab
approach for detecting failures in PV modules….