Measurement Artefacts due to the use of Flash Simulators C. Monokroussos * , R. Gottschalg, A.N. Tiwari, D.G. Infield Centre for Renewable Energy Systems Technology, Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK Abstract The measurement of solar cell current-voltage characteristics is the back-bone of today’s evaluation of photovoltaic devices. Significant differences can still occur when devices are measured in different laboratories. These variations are most significant for some newer device technologies and mostly attributed to their capacitance. This paper presents a modelling approach to investigate the effects of capacitance on photovoltaic module calibration. The measurement process is simulated based on a one diode model with additional capacitance elements, which allow the inclusion of different capacitance effects. The simulations carried out are of high capacitance silicon devices. The effects of different measurement strategies and cell capacitances on the performance parameters of solar cells are investigated. The measurement strategies simulated include various time-dependent flash durations (0.5, 1, 2, 5 and 10ms), positive and negative sweep directions and device preconditioning. To investigate the magnitude of the effects the results are compared to steady state mode data. Introduction Flash simulators have been widely used for more than 30 years to determine the I-V characteristics of solar cells. They are considered more cost effective than steady state testers, as they can provide good light uniformity and intensity with a brief pulse emission. Moreover, mounting the measured cell to a temperature stabilizing device is not required, because the short duration of the flash does not excessively heat the cell. It is well established that calibration of reference devices, spectral mismatch [1] and cell capacitance are the main reasons for any inaccuracies in the flash method. In this paper measurement artefacts related to the latter are investigated. The impact of transient errors has gained in importance recently because new, high efficiency flash simulator measurements have recently concerned many scientists. Attention to the problem was given by Friesen and Ossenbrink, who studied capacitance effects in high-efficiency solar cells [2]. Metzdorf et al [3] and Lipps et al [4] suggested correction methods for the I-V curves, reducing the capacitance effects. Keogh et al [5] have also studied the problem and proposed an innovative constant-voltage flash tester technique, which is less sensitive to transient errors. However, it is not as effective for higher currents, which again are present for high efficiency devices. The problem is compounded as these devices have shown higher capacities than conventional ones. The * corresponding author: Tel.: 01509-228140, Fax.: 01509-610031, email: C. Monokroussos@lboro.ac.uk