Only if a PV system achieves the expectedlifetime and delivers the performance it wasdesigned for the inverstors can expect that theirinvestment will be successful.However - even if PV systems are considered tobe “simple” – there are multiple error sourcesduring design, construction and operation phasewhich can violate the system performance.Either temporarily - or even worse permanently.This venue targets to highlight some of themeasures to avoid or eliminate the most importantfailures, to identify preventive measures orrefurbishment approaches as well as solutionapproaches to deal with new challenges for PVplant operators.