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A Dynamic Cell-by-Cell PV System Model to Predict Lifetime Performance and Reliability
M. Mikofski, M. Anderson, S. Caldwell, D. DeGraaff, E. Hasselbrink, D. Kavulak, R. Lacerda, D. Okawa, Y.-C. Shen, A. Tedjasaputra, A. Terao, Z. Xie
Degradation, Performance, Reliability, Modelling / Modeling
Advanced Photovoltaics : New Concepts and Ultra-High Efficiency
Subtopic: Fundamental Studies
Event: 26th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1BO.10.1
105 - 112
ISBN: 3-936338-27-2
Paper DOI: 10.4229/26thEUPVSEC2011-1BO.10.1
0,00 EUR
Document(s): paper


Predicting lifetime performance of PV systems is critical for determining the cost of solar energy. This paper introduces a physics-based model that predicts hourly performance, degradation and reliability of SunPower back-contact cells in a PV system using a series of one-diode cell models and sub-models for all major degradation modes. Other components such as encapsulant, bypass diodes and solder joints are also modeled. A cell-by-cell approach enables simulation of degradation modes that depend on cell differences and effects of mismatch caused by degradation and external stresses. This paper summarizes the degradation mechanisms included in the model, such as photo-thermal encapsulant degradation, cell degradation from UV, reverse bias and polarization, soiling and failure of bypass diodes and solder-joints from thermal-cycling. Ambient conditions and PV system configuration are used as inputs to the model. Predicted and measured average yearly degradation rates agree within 20%. This general approach can be adapted to different PV systems and can incorporate other degradation and failure mechanisms.