Optimum sizing of stand-alone wind-photovoltaic hybrid systems for representative wind and solar potential cases of the Greek territory J.K. Kaldellis n , D. Zafirakis Lab of Soft Energy Applications & Environmental Protection, Mechanical Engineering Department, TEI Piraeus, Egaleo, Greece article info Article history: Received 8 July 2011 Received in revised form 29 March 2012 Accepted 14 April 2012 Available online 15 June 2012 Keywords: Renewable energy Energy autonomy First installation cost Battery storage Remote consumer Remote islands Greece abstract Wind and solar driven stand-alone systems can under certain conditions comprise attractive electrification solutions for numerous isolated consumers worldwide. However, due to their require- ment for considerable energy storage capacity, diesel generator sets are normally used instead. To minimize oil consumption, the idea of creating a combined wind — photovoltaic (PV) based hybrid system with the use of an appropriate energy storage device is currently investigated. In this context, the main target of the specific work is to estimate the appropriate size of a similar system, so as to meet the energy demand of typical remote consumers under the criterion of minimum first installation cost. Representative case studies of the Greek territory with different quality of wind and solar potential are currently investigated, with the results obtained designating the advantages of the proposed solution, especially for locations of low wind potential. Furthermore, according to the results, the critical role of the local wind potential on the optimum size of such configurations is reflected, while variation of the local solar potential in the Greek territory seems to only slightly influence the minimum first installation cost solutions. & 2012 Elsevier Ltd. All rights reserved. 1. Introduction There are several research works (Fragaki and Markvart, 2008; Kaldellis, 2001; Kaldellis et al., 2003; Weisser, 2004) investigating the performance of stand-alone systems, destined to meet the electrification requirements of isolated consumers worldwide on the basis of either wind power or solar energy. According to the conclusions of these studies, to satisfy electricity demand at all times, i.e., during calm spells and night-time as well, considerable energy storage capacity is required so as to store any energy surplus during high wind speed and high solar radiation periods. However, the direct result of this strategy is excessive energy storage capacity that also leads to increased first installation and operation costs. At the same time, in several areas of our planet wind speed and solar radiation present supplementary (Kaldellis et al., 1999) availability, hence the combined exploitation of the available wind and solar potential may reduce considerably the energy storage capacity requirements of stand-alone systems, taking into account that although the solar energy distribution is basically periodic, wind speed may present stochastic patterns. To this end, there are several studies examining performance of similar systems. More precisely, Notton et al. (2011) studied the performance of hybrid wind-photovoltaic (PV) systems for the area of Corsica, considering different wind potential areas and designating the important factor of complementarity between wind and solar potential. Next, Ekren and Ekren (2009), investi- gated the performance of a similar configuration under two distinct load demand profiles, using detailed wind and solar measurements from a meteorological station installed in Izmir. Accordingly, Diaf et al. (2008) also studied the techno-economic performance of a wind-PV system for the area of Corsica, examining three different sites of distinct characteristics on the basis of loss of power supply probability. Moreover, Khatib et al. (2012) studied the possibility of applying hybrid wind-PV config- urations in the area of Kuala Terengganu, Malaysia, while finally, Nandi and Ghosh (2010) investigated the prospects of such systems for remote areas of Bangladesh, in comparison to the alternative of electricity grid extension. At the same time, investigation of the hybrid wind-PV solution is not yet undertaken for the remote communities of the Greek territory. In this regard, an effort is undertaken in the present work so as to examine the prospects of applying such configura- tions in Greece, complementing previous works of the authors concerning applicability of wind only- and PV only-based stand alone systems (Kaldellis, 2001; Kaldellis et al., 2003). In this context, at the east side of the Greek mainland, where the area of the Aegean Archipelago is located, there are several hundreds of scattered islands. In the specific region there is a considerable number of isolated consumers (Kaldellis, 2001; Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jweia Journal of Wind Engineering and Industrial Aerodynamics 0167-6105/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jweia.2012.04.013 n Corresponding author. Tel.: þ30 210 5381237; fax: þ30 210 5381348. E-mail address: jkald@teipir.gr (J.K. Kaldellis). URL: http://www.sealab.gr (J.K. Kaldellis). J. Wind Eng. Ind. Aerodyn. 107–108 (2012) 169–178