Afshin Andreas

TL;DR: In this paper, a step-by-step procedure for implementing an algorithm to calculate the solar zenith and azimuth angles in the period from the year −2000 to 6000, with uncertainties of ± 0.0003°.

TL;DR: The measurement and instrumentation team within the Distributed Energy Resources Center at the National Renewable Energy Laboratory, NREL, calibrates pyranometers for outdoor testing solar energy conversion systems as mentioned in this paper.

TL;DR: In this article, the performance of 51 commercially available and prototype radiometers used for measuring global horizontal irradiances or direct normal irradiances (DNI) was compared under clear sky, partly cloudy, and mostly cloudy conditions to reference values of low estimated measurement uncertainties.

TL;DR: In the most comprehensive pyrheliometer comparison known to date, 33 instruments were deployed to measure direct normal solar radiation over a 10-month period in Golden, Colorado as discussed by the authors.

TL;DR: In this paper, the authors describe the sources and magnitudes of uncertainty associated with calibrations and measuremens using spectral radiometric measurement systems for photovoltaic (PV) applications.