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Uncertainty Propagation of Spectral Matching Ratios Measured Using a Calibrated Spectroradiometer
D. Pavanello, R. Galleano, R. Kenny, H. Müllejans
Reference Cell, Monte Carlo Simulation, Measurement Uncertainty, Component Cells, Concentrator Photovoltaics, Standardization
New Materials and Concepts for Photovoltaic Devices
Subtopic: Fundamental Studies
Event: 33rd European Photovoltaic Solar Energy Conference and Exhibition
Session: 1AO.1.5
11 - 17
ISBN: 3-936338-47-7
Paper DOI: 10.4229/EUPVSEC20172017-1AO.1.5
0,00 EUR
Document(s): paper, presentation


The international standard IEC62670-3 "Photovoltaic Concentrators (CPV) Performance Testing – Part 3 - Performance Measurements and Power Rating" sets the guidelines for power measurement of a CPV device, both under indoor and outdoor conditions. When measuring under outdoor conditions, the acquired data have to be filtered “a posteriori”, in order to select only those points measured with ambient conditions close to the Concentrator Standard Operating Conditions (CSOC). The most stringent requirement to be met is related to the three Spectral Matching Ratios (SMR), which have all to be within the limit of 1.00 ± 0.03. SMR are usually determined by the ratio of the currents of component reference cells set to monitor the outdoor spectral ratio conditions during the CPV device power measurements. Alternatively the SMR can be calculated from measured spectral irradiance if the spectral responsivities of the junctions are known. Experience demonstrates that obtaining real world data meeting these strict conditions is very difficult in practise. However, increasing the acceptable range would make the entire filtering process less appropriate from a physical point of view. Given the importance of correctly measuring the SMR, an estimate of their associated measurement uncertainties is needed to allow a proper assessment of the validity of the 3% limit. In this study a Monte Carlo simulation has been used, to allow a preliminary estimation of the propagation of uncertainties for SMR measured with a calibrated spectroradiometer. The method consists of applying both random and wavelength correlated errors to the measured spectra and to the spectral responsivities of the three CPV cell junctions, accordingly to the measurement uncertainties of the European Solar Test Installation (ESTI). The experimental data used in this study have been acquired during clear sky conditions in May 2016, at ESTI's facilities in Ispra, northern Italy (45°49N 8°37E ). Several considerations are then inferred in the case of SMR measured with component reference cells.