Minimum cost solution of wind–photovoltaic based stand-alone power systems for remote consumers J.K. Kaldellis n , D. Zafirakis, K. Kavadias Lab of Soft Energy Applications & Environmental Protection, Mechanical Eng. Dept., TEI Piraeus, P.O. Box 41046, Athens 12201, Greece article info Article history: Received 16 July 2011 Accepted 17 November 2011 Available online 21 December 2011 Keywords: Hybrid system Wind and solar potential Battery energy storage abstract Renewable energy sources (RES) based stand-alone systems employing either wind or solar power and energy storage comprise a reliable energy alternative, on top of conventional diesel-electric generator sets, commonly used by remote consumers. However, such systems usually imply the need for oversizing and considerable energy storage requirements leading to relatively high costs. On the other hand, hybrid configurations that may exploit both wind and solar potential of a given area may considerably reduce energy storage capacity and improve the economic performance of the system. In this context, an integrated techno-economic methodology for the evaluation of hybrid wind– photovoltaic stand-alone power systems is currently developed, aiming at the designation of optimum configurations for a typical remote consumer, using economic performance criteria. For the problem investigation, the developed evaluation model is applied to four representative areas of the Greek territory with different wind potential characteristics in order to obtain optimum configurations on the basis of minimum initial investment, 10-year and 20-year total cost. According to the results obtained, the proposed solution is favorably compared with all other stand-alone energy alternatives, reflecting the ability of hybrid systems to adjust even in areas where the local RES potential is not necessarily of high quality. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction Renewable energy sources (RES) based stand-alone systems contribute considerably – through the production of clean energy – to both the protection of the environment and the elimination of the dependence on oil imports. On the other hand, according to arguments, such systems induce relatively high costs when compared to the conventional diesel-oil based energy solution, this largely prohibiting their broad diffusion. However, there are several authors and studies (e.g. Kaldellis, 2002a, 2004, 2010; Kaldellis et al., 2007; Shen, 2009) supporting the fact that either wind power- or photovoltaic (PV)-based stand-alone systems, if properly sized, may definitely compete with the conventional solution of diesel-electric generator sets. On top of that, according to many researchers (Diaf et al., 2007, 2008a; Notton et al., 2011), combined exploitation of the available wind and solar potential of a given area may significantly reduce the dimensions of a stand- alone system (energy storage requirements included) and thus further decrease the corresponding energy production cost. Nevertheless, as Zhou et al. (2010) point out ‘‘continued research and development effort in this area is still needed for improving the systems’ performance’’. In this context, in Europe and more specifically in Greece, there are several isolated consumers (such as private farms, tiny villages, shelters, lighthouses, telecommunication stations, etc.) that cannot appreciate access to an electrical grid and have up to now covered their urgent electrification needs based on the use of small oil-fired electrical generators, this considered to be their only energy option. In fact, estimated number of isolated con- sumers in Greece alone corresponds to more than 50,000, while the respective number for the entire EU approximates 500,000 (Kaldellis et al., 2004a). Taking into account that most of the Greek regions possess – due to the geographical position of Greece – an abundant and reliable solar energy supply all year round (Katsoulis and Papachristopoulos, 1978), as well as that their majority also appreciates remarkable wind potential (Lalas et al., 1983), Fig. 1, the idea of creating a combined wind–PV system with the existence of an appropriate energy storage device (Kaldellis et al., 2009), already widely acknowledged (Arribas et al., 2010; Diaf et al., 2008b; Nakata et al., 2005; Nandi and Ghosh, 2010), is currently considered. More specifically, to face the urgent electrification problems of remote consumers, the present work is devoted on the techno- economic study of an integrated RES based stand-alone installa- tion, based on a micro wind converter, a small PV generator and Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/enpol Energy Policy 0301-4215/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2011.11.054 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). Energy Policy 42 (2012) 105–117