International Collaboration Framework for the Calculation of Performance Loss Rates: Data Quality, Benchmarks, and Trends (Towards a Uniform Methodology)

Sascha Lindig, David Moser, Alan Curran, Kunal Rath, Arash Khalilnejad, Roger French, Magnus Herz, Björn Müller, George Makrides, George Georghiou, Andreas Livera, Mauricio Richter, Julián Ascencio-Vásquez, Mike van Iseghem, Mohammed Meftah, Dirk Jordan, Chris Deline, Wilfried van Sark, Joshua Stein, Marios TheristisBennet Meyers, Franz Baumgartner, Wei Luo

Research output: Contribution to journalArticlepeer-review

24 Scopus Citations


The IEA PVPS Task 13 group, experts who focus on photovoltaic performance, operation, and reliability from several leading R&D centers, universities, and industrial companies, is developing a framework for the calculation of performance loss rates of a large number of commercial and research photovoltaic (PV) power plants and their related weather data coming across various climatic zones. The general steps to calculate the performance loss rate are (i) input data cleaning and grading; (ii) data filtering; (iii) performance metric selection, corrections, and aggregation; and finally, (iv) application of a statistical modeling method to determine the performance loss rate value. In this study, several high-quality power and irradiance datasets have been shared, and the participants of the study were asked to calculate the performance loss rate of each individual system using their preferred methodologies. The data are used for benchmarking activities and to define capabilities and uncertainties of all the various methods. The combination of data filtering, metrics (performance ratio or power based), and statistical modeling methods are benchmarked in terms of (i) their deviation from the average value and (ii) their uncertainty, standard error, and confidence intervals. It was observed that careful data filtering is an essential foundation for reliable performance loss rate calculations. Furthermore, the selection of the calculation steps filter/metric/statistical method is highly dependent on one another, and the steps should not be assessed individually.

Original languageAmerican English
Pages (from-to)573-602
Number of pages30
JournalProgress in Photovoltaics: Research and Applications
Issue number6
StatePublished - 2021

Bibliographical note

Publisher Copyright:
© 2021 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.

NREL Publication Number

  • NREL/JA-5K00-77904


  • degradation rate
  • performance loss rate
  • PV system degradation
  • PV system performance


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