Quantify Photovoltaic Module Degradation using the Loss Factor Model Parameters

Photovoltaic (PV) system investments expect to produce power for 20 plus years. However, module level degradation can occur that reduces the overall energy production. This experiment adds to the current work by using the Loss Factor Model (LFM) to evaluate current and voltage curves acquired from two different module types deployed in three distinct climate zones. The experiment first calculated the six LFM parameters for each year of the data set. Then, the annual LFM parameters were compared to identify changes in performance. The approach identified an increase in series resistance that would have otherwise gone unnoticed using methods that evaluate the maximum power point data only. The annual LFM parameter degradation rates for one of the modules in a single climate zone were then used to predict the voltage and current for a similar module type in a different climate zone.