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Proceedings Paper

Photovoltaic efficiency measurements
Author(s): Keith Emery
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Paper Abstract

Photovoltaic power conversion efficiency is the single most important performance indicator. This paper gives an overview of procedures to determine the efficiency with respect to standard conditions. The measurement theory and general procedures for determining the efficiency with respect to reference conditions are well understood. The engineering challenge of commercial or custom equipment to perform accurate efficiency measurements for all photovoltaic technologies is discussed. Accurately measuring the performance of multijunction devices requires adjusting the intensity and spectral content of the light source so that each junction generates the proper photocurrent. Organic devices often have time constants on the photocurrent in excess of 1 s. This poses a variety of problems when measuring the quantum efficiency under 1-sun illumination or measuring the current-voltage characteristics. Many photovoltaic cells have reversible and irreversible transients in the current and/or voltage. Module acceptance testing and qualification procedures often assume that these transients are not present. The sample with the highest efficiency may not produce the highest energy because the photovoltaic performance is a function of the spectral content of the light, total irradiance, and temperature-all of which are different in the "real world" than under standard reference conditions.

Paper Details

Date Published: 3 November 2004
PDF: 9 pages
Proc. SPIE 5520, Organic Photovoltaics V, (3 November 2004); doi: 10.1117/12.562712
Show Author Affiliations
Keith Emery, National Renewable Energy Lab. (United States)

Published in SPIE Proceedings Vol. 5520:
Organic Photovoltaics V
Zakya H. Kafafi; Paul A. Lane, Editor(s)

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