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International Journal of Photoenergy
Volume 2006, Article ID 27274, 7 pages

Load matching in a direct-coupled photovoltaic system-application to Thevenin's equivalent loads

1Department of Informatics & Communications, Technological Educational Institution of Serres, Terma Magnesias, P.O. Box 62124, Serres, Greece
2Department of Chemistry, Aristotle University of Thessaloniki, University Box 116, Thessaloniki 541 24, Greece
3Department of Informatics and Computer Technology, Technological Educational Institution of Lamia, 3rd Km ONR Lamias-Athinas, Lamia 35100, Greece
4Department of Natural Resources & Environment, Technological Educational Institution of Crete, Romanou 3, Chania 731 33, Greece

Received 25 February 2005; Revised 24 August 2005; Accepted 5 September 2005

Copyright © 2006 A. Balouktsis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A methodology is developed for the assessment of load matching and further estimation of the optimum photovoltaic (PV) arrays arrangement over a prolonged period of time. The method calls for the calculation of the appropriate effectiveness factor defined as the ratio of the load energy over the maximum energy that can be produced by the PV array for a specific time period. The effectiveness factor depends on the PV array characteristics, the load characteristics, and the solar irradiance conditions. To produce realistic predictions for the effectiveness factor and the PV arrays arrangement with validity over long periods of time, the present statistical model describing irradiance employs a stochastic variation of solar radiation over a long period of time and not just a fixed diurnal variation as traditionally done in the past. Simulations are performed for the case of Thevenin's equivalent loads. In order to generalize the analysis, the simulation results are presented in a reduced form based on the values of the voltage and current corresponding to the maximum power of the PV array. The results are presented in multiple-curve comprehensive plots, which allow to determine the optimum photovoltaic array panel's arrangement without engaging sophisticated mathematical calculations.