Review of photovoltaic module degradation, field inspection techniques and techno-economic assessment

Considering the relevance of photovoltaic technology in the power generation system, degradation and failure of photovoltaic modules are becoming particularly relevant. To adopt and coordinate preventive measures or actions, defects must be understood, detected and their economic impact evaluated. The variety of different degrading effects are categorized and the most significant ones as well as in-field characterization methods are described in detail. This information is summarized in a matrix showing signatures of important defects using different inspection methods and stating related power losses. The development of economic assessments is shown, resulting in a cost-based failure modes and effects analysis with the recently developed cost priority number. How the economic impact of a defect is estimated by the cost priority number is shown in three use cases, namely cell cracks, short circuit bypass diode and potential induced degradation. For each case, the fixing costs are evaluated in comparison to defect related downtime costs. Ultimately, to rank the usefulness of the calculations, influences beyond the financial factor are discussed.