Photovoltaic (PV) systems are one of the only electronic devices that are expected to survive outdoors for 25 to 30 years making module and system quality one of the cornerstones of guaranteed return on investments.    Although R&D in PV reliability has made tremendous progress in the last decades the work is far from done.    Many problems remain still a puzzle and as technology evolves new challenges are also on the rise. PID (potential-induced degradation) is one of the most critic...