Photovoltaic (PV) modules and associated module level power electronics are sold with warranties exceeding 25 years, which is unprecedented for any product that operates in some of the harshest possible environmental conditions without any possibility of repair. Due to difficulties in developing PV module and system level service life models, the PV industry has traditionally relied on the discrete Develop-Test-Analyze-Fix methodology. However, going forward, this approach is proving to be too slow and cost prohibitive. As a promising alternative, a Physics of Failure (PoF) based approach that comes under the paradigm of Design for Reliability (DfR) is discussed to address the contemporary challenges in PV cells, modules and systems with the case studies on Potential Induced Degradation (PID) and Bypass Diode Reliability. PID is an important failure mode which has affected large number of PV modules in field. Results from Finite Element Analysis simulations will be used to elucidate the dominant leakage current pathways responsible for PID. Bypass diode failures immediately put the module out of warranty and are being realized as imminent issue that will be facing the PV industry. The modeling framework for thermal runaway risk assessment of bypass diodes will be discussed along with accelerated test development for other diode failure modes. Potential extensions of this approach for power semiconductor devices will be touched upon. Overall, the PoF approach involves improving understanding of failure mechanisms to develop device / component level predictive models to have built-in reliability into the electronic products and systems. PoF and DfR have already begun to revolutionize the electronics industry by integrating the device design, fabrication and reliability testing.
Dr. Narendra Shiradkar has been working as Photovoltaic Research Engineer at Jabil Solar and Environmental Test Center, St. Petersburg, Florida, USA, since 2015. He is responsible for design and reliability R&D at PV component, module and power electronics levels to support Jabil's PV module manufacturing facility of ~ 1 GW/year. In the PV reliability community, he is known for his contribution on bypass diode reliability. His research has been instrumental in leading the activities of the Task Group 4 on Diodes of the International PV Quality Assurance Task Force since 2014. His work is shaping the development of upcoming standard IEC 62979 on thermal runaway and revisions to the bypass diode test in existing standard IEC 61215. He obtained his PhD in Electrical Engineering from Florida Solar Energy Center, University of Central Florida in 2015. Before that, he obtained his Dual Degree (B.Tech in Electrical Engineering and M.Tech in Microelectronics) from Indian Institute of Technology Bombay, in 2011.