TUTORIAL

Nicola Trivellin

University of Padova, Italy

Photovoltaic systems are expected to operate for decades while maintaining high energy yield and electrical safety. Their environmental benefit and economic viability therefore depend not only on initial conversion efficiency, but also on the ability to quantify degradation, detect incipient failures, and distinguish actual defects from variations caused by irradiance, temperature, and operating conditions. Nevertheless, the translation of laboratory measurements into reliable assessments of field performance remains challenging because of interacting environmental stressors, heterogeneous degradation mechanisms, and measurement uncertainty.

This tutorial presents a measurement-oriented framework for assessing the reliability of photovoltaic cells and modules, from controlled accelerated tests to in-field diagnostics. Starting from the distinction between gradual performance degradation and discrete failure events, the main degradation mechanisms—including light-induced degradation, potential-induced degradation, reverse-bias hot spots, and climatic or mechanical damage—are connected to their measurable electrical, optical, and thermal signatures.

Laboratory approaches based on damp-heat exposure, thermal cycling, irradiation, high-voltage stress, and reverse-bias testing are discussed, with particular attention to test conditions, baseline and post-stress characterization, and the limitations of extrapolating accelerated-test results to service lifetime. Electrical characterization through light and dark current-voltage measurements is complemented by electroluminescence, photoluminescence, ultraviolet fluorescence, and infrared thermography. For each technique, the tutorial examines the measurement setup, relevant influence quantities, spatial resolution, sensitivity, repeatability, and possible sources of misinterpretation.

Finally, field inspections and UAV-based RGB and infrared imaging are presented through practical case studies involving cell cracks, hot spots, disconnected substrings, junction-box failures, potential-induced degradation, and hail damage. The complementarity of multiple techniques is highlighted as the basis for increasing diagnostic confidence and supporting condition-based maintenance. Overall, the tutorial demonstrates how traceable and correctly interpreted measurements can contribute to lifetime extension, reduced maintenance costs, lower material consumption, and more sustainable photovoltaic energy production.

Nicola Trivellin is an Associate Professor of Electronics at the Department of Industrial Engineering, University of Padova, Italy. His research focuses on the characterization, reliability, and failure analysis of photovoltaic cells and modules and optoelectronic semiconductor devices. His activities include electrical, optical, and thermal measurement techniques, accelerated stress testing, environmental degradation, and laboratory and field diagnostics. His research interests also encompass flexible and emerging photovoltaic technologies, solid-state lighting, visible light communication, energy harvesting, and energy-efficient embedded measurement systems. He is an Associate Editor of the IEEE Journal of Photovoltaics and a member of the IEEE Instrumentation and Measurement Society, IEEE Reliability Society, IEEE Electron Devices Society, and SPIE. He has authored or co-authored more than 200 scientific publications and is an inventor or co-inventor of nine national and international patent applications. He has coordinated research activities within several national and European projects, including PNRR NEST – Network 4 Energy Sustainable Transition, PNRR SERICS, HEIMAT, and AI-Twilight. He is also a co-founder of the LightCube university spin-off and has coordinated applied research activities with industrial partners including Artemide, Infineon Technologies, and Applied Materials. His recognitions include Best Paper Awards at the IEEE Sustainable Smart Lighting World Conference 2023, IEEE MetroSea 2021, and ESREF 2009.