PV Plant Performance Loss Rate Assessment: Significance of Data Filtering and Aggregation

The performance loss rate (PLR) of a PV plant - comprised of reversible and irreversible (a.k.a., degradation) reduction to power nameplate - is a key parameter for predicting long-term energy production, informing the levelized cost of electricity calculations, and benchmarking PV plant performance. Analyzing plant power production data over time is a common and practical method to calculate the performance loss rate of a PV plant. Studies to date have used various data filtering and aggregation criteria, which affects the PLR, makes it difficult to compare reported literature values, and to benchmark plant performance. This paper presents a sensitivity analysis of the impact of various data filtering and aggregation choices on the calculated PLR using power production values from an 8.4-MWac PV plant. Findings indicate the need for industry consensus on appropriate best practices for calculating and reporting PLR, including data filtering and aggregation criteria.