Outdoor Rating Conditions for Photovoltaic Modules and Systems

Sarah R. Kurtz, Daryl Myers, Tim Townsend, Chuck Whitaker, Alex Maish, Roland Hulstrom, K. Emery

Research output: Contribution to journalArticlepeer-review

31 Scopus Citations


Historically, flat-plate photovoltaic modules have been given a 'peak-watt' rating indicating the power generated under 1000 W/m2 global irradiance at a standard temperature. However, questions have arisen regarding the direct-normal irradiance, ambient or cell temperature, and wind speed (when it is specified) that should be used for evaluating the performance of flat-plate and concentrator modules. By studying the conditions that are observed when the global irradiance on a 2-axis-tracked surface is 1000 W/m2, our analysis provides an objective, quantitative basis for the choice of the 'peak-watt' rating conditions for both types of collectors. These observed conditions are consistent with commonly used values of 850 W/m2 for direct-normal irradiance and 20°C for ambient temperature. Evidence is given that wind speed should be increased from the commonly used 1 m/s to a more frequently observed 4 m/s.

Original languageAmerican English
Pages (from-to)379-391
Number of pages13
JournalSolar Energy Materials and Solar Cells
Issue number4
StatePublished - 2000

NREL Publication Number

  • NREL/JA-520-27160


Dive into the research topics of 'Outdoor Rating Conditions for Photovoltaic Modules and Systems'. Together they form a unique fingerprint.

Cite this