Analysis of performance degradation of domestic monocrystalline photovoltaic systems for a real-world case

To solve the problems caused by usage of fossil fuels, it is important to make a transition to renewable sources of energy. Installing photovoltaic (PV) systems is one of the most popular techniques in renewable energy production. And as PV penetration is increasing, it becomes more critical to measure how the performance of PVs is changing over time. In this work, the degradation rates of installed real-world PVs at a house in the Netherlands are evaluated. They are measured by applying Seasonal and Trend decomposition using Loess (STL) technique on the time series of the performance and extracting the trend of changes during years. Also the degradation rates of PVs that are located in the same position and have the same orientation are compared. Results show that the average of degradation rates of studied PVs is 0.923 % / year. On the other hand, PV systems that are closer to the growing trees exhibit higher degradation rates due to the increasing in the length of shadow periods.