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From Sunlight to Power: The History of Achieving a Globally Harmonised Approach to PV Measurement
H. Müllejans, W. Zaaiman, E.D. Dunlop
Calibration, Reference Cell, Measurement Uncertainty, Traceability, WPVS
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4DP.1.1
778 - 782
ISBN: 3-936338-60-4
Paper DOI: 10.4229/EUPVSEC20192019-4DP.1.1
0,00 EUR
Document(s): paper, presentation


The measurement of PV module power and energy rating requires necessarily the determination of the incident solar irradiance. This used to be the major contribution to measurement uncertainty (UC) and therefore efforts have been undertaken since the 1980s to develop and harmonise the measurement of irradiance with PV reference cells. In the mid 1990s the World Photovoltaic Scale (WPVS) was established. Based on this starting point, the concept was followed up by the European Solar Test Installation (ESTI) enlarging the number of contributing results and applying advanced data analysis methods, namely the determination of the WPVS calibration values as Key Comparison Reference Value (KCRV) usually employed in intercomparisons between National Metrology Institutes (NMI). This led to PV reference cells being able to measure the incident solar irradiance with an UC around 0.25%, the lowest worldwide for any PV device. Furthermore secondary calibrations of PV reference cells and PV modules are possible with an UC of 0.5% and 1.0% respectively. The WPVS has led to world-wide consistency in PV module power measurement and contributes to improved accuracy of PV energy rating.