Radiometric instrumentation and measurements guide for photovoltaic performance testing

Abstract

The Photovoltaic Module and Systems Performance and Engineering Project at the National Renewable Energy Laboratory performs indoor and outdoor standardization, testing, and monitoring of the performance of a wide range of photovoltaic (PV) energy conversion devices and systems. The PV Radiometric Measurements and Evaluation Team (PVSRME) within that project is responsible for measurement and characterization of natural and artificial optical radiation which stimulates the PV effect. The PV manufacturing and research and development community often approaches project members for technical information and guidance. A great area of interest is radiometric instrumentation, measurement techniques, and data analysis applied to understanding and improving PV cell, module, and system performance. At the Photovoltaic Radiometric Measurements Workshop conducted by the PVSRME team in July 1995, the need to communicate knowledge of solar and optical radiometric measurements and instrumentation, gained as a result of NREL`s long-term experiences, was identified as an activity that would promote improved measurement processes and measurement quality in the PV research and manufacturing community. The purpose of this document is to address the practical and engineering need to understand optical and solar radiometric instrument performance, selection, calibration, installation, and maintenance applicable to indoor and outdoor radiometric measurements for PV calibration, performance, and testing applications. An introductory section addresses radiometric concepts and definitions. Next, concepts essential to spectral radiometric measurements are discussed. Broadband radiometric instrumentation and measurement concepts are then discussed. Each type of measurement serves as an important component of the PV cell, module, and system performance measurement and characterization process.