As far as world energy demands constantly increase (approximately doubled within last ten years) and deposits of fossils are limited, the need for alternative energy production use is nowadays more than necessary (Olabi, 2013). In addition, the pollution produced by using conventional energy sources enforces the exploitation of renewables (RES) use, since the environmental impact of current energy production and use, sounds nearly irreversible. As far as renewables’ technology becomes mature with the years, hybrid photovoltaic / wind power systems have recently become feasible alternatives that satisfy the requirements for low electricity production with environmental protection (Rathore & Panwar, 2007). For the most efficient and economical use of solar and wind energy, a combination of these two systems can be utilized in the form of a hybrid photovoltaic / wind system, whose optimal dimensioning plays an important role. In hybrid systems, battery arrays are used as buffering systems, being able to store the generated energy in order to use it when the RES are not available. Given the environmental potential for a specific location, a hybrid photovoltaic / wind system combined with an energy storage system is an interesting option to cover relatively low electrical loads in remote areas (Ansong et al., 2017; Forde, 2017; Boute, 2016; Sandwell et al., 2016) where either there is no utility for power supply or it is difficult and cost-ineffective to attain a continuous interconnection to the existing grid. These systems can offer high reliability for supplying electricity under various environmental conditions, as well as savings in the cost of the energy produced (Veldhuis & Reinders, 2015). Also, these systems can store electricity not only by using batteries but also using alternative options for electricity energy storage, such as flywheels, superconductors, etc. (Lin et al., 2013).[10] Currently, several attempts have been integrated towards the implementation, the theoretical investigation and design as well as the optimization of off-grid applications for autonomous electricity production. Bentouba & Bourouis (2016) evaluated the feasibility of a hybrid renewable energy system for electricity generation in a location of an extreme south area of Algeria with no electricity connection, using the well-known HOMER platform. By using the same software, the off-grid electrification of three villages in Colombia using different combinations of wind turbine, PV and diesel generator to determine the most energy efficient and cost-effective configuration for each location has been also presented (Mamaghani et al., 2016). Furthermore, the electrification of two rural villages in South Africa has been achieved through investigation of the viability of a hybrid mini-grid as a solution for rural development (Azimoh et al., 2016). The feasibility of hybrid electricity systems consisting of small scale generating sets, hydro, solar PV with or without energy storage solutions have been studied, mainly focused on the electric load for the basic needs of a rural community in Papua-New Guinea (Kaur & Segal, 2017). Le Guen et al. (2018) worked on improving energy sustainability of a Swiss village by integrate renewable technologies and by building renovations, while three scenarios were considered for solar PV integration and energy system improvements. Rural electrification in some Malaysian areas also presented by Fadaeenejad et al. (2014), while an overview of applied hybrid renewable energy system (HRES) for worldwide villages with special attention on Malaysia has been proposed. A flexible hybrid renewable energy system design for a typical remote village located in tropical climate in Malaysia using several scenarios for off-grid and on grid connections which were performed using HOMER software has been presented by Halabi & Mekhilef (2017). The operational behaviors for all of the configurations were investigated and quantified to demonstrate the benefits/risks associated with each system and determine viable flexible design(s). Optimization of discrete cogeneration systems with storage capacity and decision support for dynamic solar hybrid combined heat and power systems in isolated rural villages in Africa, has been published by Prinsloo et al. (2016), where a multi-objective optimization solution with hierarchical digital microgrid control is described. Renewable microgrid projects for autonomous small-scale electrification in Andean territories can be also found in the work of Lopez-Gonzalez et al. (2017), where the decisions taken across the design process are analyzed and the suitability of these technologies to extend access to electricity is also shown. The requested power supply in these areas is achieved by the combination of wind/solar/batteries, supported by diesel generator or LPG/LNG usage in some cases. All the above presented systems have a specified application area without making clear why they are applied in this region. Actually, there is no area selection through certain criteria, no suitable system selection based on a multi-criteria analysis with a production forecast while most of these systems are of no sustainable footprint, due to the use of diesel/LPG generators. This optimization of such existing or theoretically described systems improves their operation but does not help on the choice: “which system in which area”. The last point is crucial when policy issues have been raised, since it is important for policy makers to design a feasible plan for off-grid electricity production. Obviously, this was not the case for the above-presented works, as far as the installations were always given and the research framework has inevitably been limited to operational issues, such as optimization, cost effectiveness, etc. Another important point is the sizing of such systems, where the common practice is a simple oversizing in order to assure full coverage of the load. Obviously, such a practice is not effective in terms of energy and costs, therefore various methodology techniques for hybrid PV/wind systems sizing have been reported in the literature. Diaf et al. (2007) proposed a design methodology of a standalone hybrid PV/Wind system in order to power supply a residential household. This methodology aims at finding configuration of a hybrid system in terms of technical analysis, i.e. wind, PV panel and battery storage, and does not take into account other criteria such as demographic and geographical limitations, land use, environmental and the educational level of the residents, etc. Also, it uses an one-year time series meteorological data while wind and solar power assumed to be constant during each one-Ώρες time interval. A statistical and mathematical method called Response Surface Methodology (RSM), serving to characterize the system costs for a given time-varying the Ώρεςly energy load demands, has been proposed by Ekren & Ekren (2008). Their model has been built under the assumption that input variables do not vary during specific time intervals (namely, one Ώρες). This methodology has been performed by applying two years of meteorological data while there is no reference to cost reduction (for instance, by studying different PV/wind technologies). A recent review about the sizing methodologies along with a comparison of most recent size optimization methods was presented by Luna-Rubio et al. (2012), focused on sizing hybrid energy systems with energy storage components of several types. Another review on important knowledge such as configuration of a standalone PV evaluation criteria and sizing methodologies, was also presented by Khatib et al. (2016). Meteorological data generation methods are discussed there and various parameters, such as technological, economical and sociopolitical factors, have been considered and judged. To obtain their objectives, the authors considered a standalone PV energy system and made use of Ώρεςly, daily and monthly average meteorological data. Recently, another review on recent developments in size optimization methodologies, comparison of algorithms, evaluation of all possible combinations of standalone systems including assessment parameters of economic, environmental and social aspects, has been presented by Al-Falahi et al. (2017). The emphasis there is on economic issues with a combination of solar, wind, diesel generator and battery storage while social acceptance was not taken into account. Domenech et al. (2015) developed a methodology to design standalone systems for rural communities, based on wind turbines and PV panels, where the distribution through microgrids has been considered along with economical, technical and social considerations. This design methodology incorporates the costs of a basic energy supply system that covers fundamental energy needs and furthermore, solar data were not localized, since they were extracted from worldwide meteorological stations rather than nearby ones. Furthermore, a methodology for physical and cost assessment for a transition to renewable in Russia's regions is presented by Ermolenko et al. (2017). It offers better designed and more accurate methods for calculating the exploitable technical potentials of wind and solar PV energy for a wide range of generating equipment in centralized and distributed power systems and taking into account existing social and environmental limitations. It uses NASA SSE database for meteorological information while energy potential was calculated for twelve months with an averagedaily energy value of three Ώρεςs per day. These authors also made use of two assumptions: (a) the existing energy potential characteristics were not sufficient to fully understand the investment and economic potential of renewables, and (b) the availability of wind and solar data were sufficient to cover a substantial part of existing energy demand. The reliability of hybrid systems has been raised significant research interest, but usually ignoring criteria, such as demographic, geographical, land use, environmental and educational level of the residents (Beyer & Langer, 1996, Yang et al., 2003). Another issue related to these studies is the limited period considered for the meteorological parameters used. Our study case is mainly focused in establishing a methodology for the selection of the appropriate area where a hybrid power production system could be installed. This selection must be extended to the finest design of the hybrid system as well as to the optimization of its operation. The criteria that must be satisfied according to this methodology are related with meteorology (solar radiation, wind potential), while demographic, geographical, geospatial, land use and load-satisfaction criteria must be also fulfilled. There is also a need to reduce the energy production costs, by installing the most suitable system for the specific area, where its suitability must be based on multi-criteria analysis, on the combination of meteorological data and electrical charges to be covered. Furthermore, the RES-mixture in the system as well as the possible law-limitations are some parameters we have taken into account during our analysis. The optimization procedure is driven by the full satisfaction of energy demands in a 24X7 basis (objective function). For the sake of applicability, the hybrid system is supposed to be installed in small Greek settlements (up to 100 residents), with known low energy demands. To this end, an algorithm has been developed to identify the appropriate area for the installation of the proposed hybrid (PV/Wind) power system and to optimize its operation. Special effort we have put on getting the exact picture of electric consumption of the settlements by collecting electricity consumption data directly from the electric company for the 2012-2017 period, by recording the number and the energy class of electrical appliances existing there. Exact measurements of the available space (roofs, public space, etc.) has been also performed to assure installation of the solar panels. We also examine the potential use of alternative electricity storage devices and, additionally, we have tried to quantify the social impact by means of appropriately defined indicators. Finally, we also investigate the social, demographic and economic impact of the introduction of such a hybrid system on the inhabitants of these small Greek settlements. It is widely accepted that the opinion of society has a vast impact on energy and environmental projects, as far as their implementation is facilitated by proper information, awareness raising and the mobilization of citizens and society as a whole. Located in the SE Mediterranean area, Greece is one of Europe’s sunnier regions, with an affluent and reliable supply of solar energy. On the other hand, the wind in Greece is abundant throughout the year and, especially the Aegean Islands, where a yearly high wind potential is observed. As before mentioned, it is important for energy policy makers to establish a rigid and stable methodology for the selection of the appropriate location to install off-grid power plants. In brief, the methodology of this study is based on the sequential application of specific criteria that must be satisfied by the location, the load (demands), the specific mixture of renewables used, the economic feasibility as well as by the population (residents). More precisely, the criteria are as follows: • Location Criteria, which are:  Solar radiation criterion  Wind potential criterion  Demographic Criterion  Geographical Criteria  Geospatial criteria  Land Use Criterion • Electrical Load Criteria • Renewables (PV & Wind Turbine) Criteria, which are  Photovoltaic Selection Scenarios  Selection criteria for Batteries, Inverter and Charge Controller  Criteria for the selection of wind turbines • Optimization in terms of energy of an autonomous hybrid system • Economic analysis • Social acceptance of residents. In detail the criteria of the methodology are as follows: Greece has a significant solar potential, especially when compared to the northern European countries. Average annual solar radiation in the horizontal plane varies from approximately 1400 - 1500 kwh/m2 in Northern Greece, to approximately 1800 - 1900 kwh/m2 in the southern Peloponnese, Crete and the Dodecanese (Nikitidou et al, 2015). Solar radiation shows its maximum intensity during noon (maximum solar height), both in summer and winter. Solar energy is higher during summer due to the location of the sun and the increased sunshine Ώρεςs. The Greek National Meteorological Service (NMS) records for many years the duration of sunshine per day (hr/day) and in some cases the total solar radiation (kwh/m2) in various regions/locations. The criterion for selecting of settlements is the level of measured incident solar radiation, varying in a range between 1400 kwh/m2 to 1900 kwh/m2, with mean value 1650 kwh/m2. This value is close enough to 1600 kwh/m2 calculated by Lalas et al. (1983). This mean value can be considered as a classification threshold, where areas below 1600 kwh/m2 are characterized as “low-power” and these above the 1600 kwh/m2 are “high-power” areas. Seasonal variations in atmospheric pressures (barometric low/cyclones, high barometric/counter-cylinders), combined with the development of local winds, are the key factors for characterizing Greece as a “windy European territory” (Nastos et al, 2002). Wind potential in Greece ranges from 0 m/sec to over 10 m/sec. Based on this range, the average value is 5 m/sec, being close enough to the cut-in speed of wind turbines. By following the same procedure as established for satisfying the criterion regarding Solar Radiation Data, we divide the whole territory into two classes: areas below the average wind potential are “low wind” while these above the average wind potential are “high wind”. In our study we have selected two areas of low and two areas of high wind potential. In order to assure high possibility of full load coverage by RES, we have chosen settlements presenting low demands and located at the areas of high and low solar and wind potential, as previously discussed. The population is taken from the 2011 population-housing census (Greek Statistical Authority, 2011). In any environmental potential case, we have chosen two settlements of low population range (50 - 100 residents). It is assumed that population of all the eight selected settlements can support the implementation of a hybrid RES system, with a relatively low installation cost, a relatively small amount of land that will be required to install the system, and few responses to the population by residents, as opposed to large population settlements, where the installation costs, the extent of installation of the system and the intense reactions that usually arise in such large-scale projects will be prohibitive. We have chosen two settlements in each area to study their possible interconnection to exchange extra energy. In addition, the settlements must be located as close as possible to reduce the additional interconnection costs. It has been observed that areas with high solar radiation are mainly located in the South East Aegean (Dodecanese) as well as in South Crete, while those with low solar radiation are located in Northern Greece as well as in the Northern Aegean islands (Nikitidou et al., 2015). Similarly, low wind potential areas are mainly located in mainland Greece, while high wind potential areas are those located mainly in the Aegean islands and in the western Greece. Thus, we have formed four region types: • AREA A - Low solar radiation with low wind potential • AREA B - Low solar radiation with high wind potential • AREA C - High solar radiation with low wind potential • AREA D - High solar radiation with high wind potential. We also have to evaluate the environmental legislation limitations, such as protected areas (NATURA 2000, National Parks, etc.), wildlife sanctuaries, landscapes of special natural beauty, etc. Furthermore, areas characterized as traditional settlements, historic city districts and listed buildings that are protected in architecture and urban planning by special decrees, must be avoided. According to Greek Law, these area types have no restrictions on the installation of RES but are subjected to special legislation regarding their character. Greek Law does not allow installation of wind turbines and photovoltaic panels in forest areas, streams, seashores and beaches, as well as in archaeological sites. In these areas, the verification of all parameters should be based on to the legislation in force. In this part, an on-site survey has been carried out to record the number of buildings at each settlement as well as their status (home, country house, small enterprise, public-use building). To identify the averaged load per building during a six-years period (2012-2017), it is necessary to find out the number and the energy class of electrical devices used, thus actual electrical charges can be recorded on a monthly basis with a distinction between weekdays and weekends. Electrical loads for homes are higher during weekend than during normal weekdays because people normally follow their everyday activities during working week. However, the situation is quite different during August where weekend electrical charges are lower than those in the weekdays, mainly because of summer holidays. As far as enterprises are concerned, the electrical loads of winter months are much less than those of summer months and also some weekends of the year due to visits by remote residents. Finally, public buildings in these settlements are not used for most of the time, so we are going to use them only for PV panels roof installation with battery storage. Obviously, electrical load data will be recorded in detail for each selected settlement. Initially, four PV technologies have been considered: monocrystalline silicon (m-Si), polycrystalline silicon (p-Si), amorphous silicon (a-Si) and hybrid photovoltaic elements (HIT) technology. The photovoltaic panels is supposed to be placed on the roofs as well as on plots close to the selected settlements, if necessary. PV slopes and orientation strongly depend on the latitude of the installation. Furthermore, the easy expansion of the photovoltaic installation in the future (when electrical loads increase) must be also taken into account. Batteries are necessary in any off-grid power generation system because it is the most mature storage technology in terms of energy efficiency and cost effectiveness. Energy buffering allows for the control of the produced power since RES-based production is subjected to solar and wind potential fluctuations. Batteries in such systems are subjected to high amount of charging - discharging cycles, thus the need for high discharge rate batteries is essential. In fact, batteries life varies from three to five years and mainly depends on charging/discharging cycles and operational temperature. The characteristics that batteries have to meet are low cost, high energy efficiency, prolonged lifecycle, low maintenance, durable construction, low self-discharge and wide operating temperature (Manimekalai et al, 2013). As far as PV and wind turbines are DC output devices, inverter is necessary to supply all devices requiring AC power. Depending on the power produced and the loads covered, more than one inverters might be used in one specific installation. In any case, the selection of the inverter depends on the energy output, the matching between allowable and produced power and the number of inverters used. Charge regulator is checking the status of the batteries, assuring the satisfactory charging without overload and/or low charging level issues. There is a distinguish between series and parallel (shunt) controllers. For series controllers, overcharging is prevented by disconnecting the PV array until a particular voltage-drop is detected, while, for shunt controllers, overcharging is prevented by short-circuiting the PV array (Smets et al., 2016). Wind turbines can be classified accordingly to the orientation of their axes, as follows: • Horizontal axis wind turbines, where the axis of rotation is parallel to the wind direction. They may have a large number of fins, and their impeller may be positioned according to the wind direction, in front of or behind the support tower (Kaldelis et al, 2001) and • Vertical axis wind turbines, where the axis of rotation is perpendicular to the wind flow. These devices present lower power efficiency, thus are rarely used. The technique of optimizing the initialization and operation of a hybrid stand-alone renewable energy system is based on definition of an objective function which has to be minimized under constraints. In our case, the major constrain is the 100% coverage of the load for the selected settlements by the hybrid PV/wind system. Towards this aim, three-levels of optimization are necessary. First, we must determine the optimal dimensions of the components to be installed (wind turbines, PV panels, inverters, charge regulators, cables, etc). Then, the meteorological data regarding the specific location must be evaluated and used (wind speed, solar radiation, temperature, etc.). By using these data, it is able to calculate the maximum and the expected output power, generated by the specific system in the selected location. Finally, the profile of the load to be covered by the hybrid system is embedded in the optimization procedure. The charge coverage rate, i.e. the amount of energy remaining in the batteries at any given time, is the core variable for the decision-making process as well as the process of possible interconnection between the two nearby settlements. As previously described, this decision-making process is also subjected to restrictions imposed by technology, connectivity, environmental potential and social acceptance by the residents. Beyond the criterion of full load coverage, the cost effectiveness criterion is also important. The main cost parameter for this is the Net Present Cost, representing the costs spent during project’s lifetime, calculated by taking into account the Capital Recovery Factor (Brealy & Myers 1991). The financial analysis should be extended to the estimation of depreciation rate during project’s lifetime while the final overall cost-effectiveness is calculated based also on the savings of the equivalent CO2-emissions costs. An important part of this methodology concerns the social acceptance of RES wide-use, which is largely overlooked due to growing public concerns about depletion of natural resources and environmental issues associated with conventional fossil fuels (Wuestenhagen et al., 2007). It is rather obvious that the possible reaction of society can prevent or delay these projects. However, the social acceptance issue emerged as the citizens became more aware of advantages and disadvantages of renewable energy technologies and this has led, in some areas, in social rejection of renewable energy development (Ribeiro et al., 2011, Sheinbaum-Pardo et al., 2012). In terms of projects acceptance by local community, this study should focus on some parameters such us the demographics of the installation location, the level of education of the population, elements for the social character of the area such as isolation or racial background, as well as data on its production and employment local population. Public attitudes towards renewable energy project shows a U-shape, which indicates that the public acceptance is not stable and changes over the time (Helland & Kastenholz, 2008, Sovacool, 2011). There are many benefits of improving the social acceptance of renewable energies. Social acceptance is one of the prerequisites for the successful implementation of renewable energy projects (apart from technical, economic and local aspects) regardless of it being large scale or micro scale (Heras-Saizarbitoria et al., 2013, Maack & Skulason, 2006, Sauter & Watson, 2007), and also social acceptance plays an important role regarding the location of such installations (Parkhill et al., 2010). In general, residents should be properly informed about the autonomous hybrid photovoltaic-wind turbine system prior to installation. In our case this information was achieved by a questionnaire created for this purpose and filled by the majority of the residents with the assistantship of local authorities. Residents were informed about the benefits of the hybrid system at their location, and the possibility of “training” in the use of “green” devices, i.e. devices with limited energy consumption. This training will reduce their electricity needs therefore the size of the hybrid installation would become smaller, and the economic benefit would be higher. Finally, they were informed about the possibility to work together with their neighbors through interconnection process, so that they can jointly solve the problems of managing the deficit or excess electricity that may arise in their villages. Financial issues largely affect the final decision on the installation and operation of the autonomous hybrid photovoltaic - wind turbine system. One of the most critical parameters for designing an autonomous hybrid system is its energy initial and operational costs. Since the hybrid systems do not use gasoline or LPG generators as alternative sources, the operating costs are equal to the annual replacement cost of the system (Prodromidis & Coutelieris, 2014). Our questionnaire includes questions regarding financial issues. The answers showed that although energy reduction and also energy consumption is an important issue for the residents of the selected settlements, very few of them are trying to reduce energy by mainly using led lamps and low-energy consumption appliances. One major remark is that residents are not intended to pay more for financing energy actions but the majority of the them are willing to upgrade their energy powerful appliances, if adequate financing is offered and they are also willing to produce their own electricity. An important factor is their willingness to cooperate with their neighboring village to handle energy. Summarizing, residents, on the one hand, want to reduce energy consumption, to upgrade energy appliances and to produce their own electricity, and they also developed a form of cooperation with their neighboring settlement for the sake of reducing electricity consumption and hence decreasing the money that they pay to electricity production and distribution company. On the other hand, they do not reduce energy consumption and they do not want to pay extra money for financing additional energy actions, probably because of the bad economic situation in Greece. The methodology has been applied to design a standalone (off - grid) hybrid wind turbine - photovoltaic system with battery storage for small-scale settlements. Following the above-presented criteria, the selected areas are as follows: • Low solar and low wind potential (AREA A): Repetista and Areti, villages at Kalpaki, Ioannina, Epirus, • Low solar and high wind potential (AREA B): Hagia Sophia and Fisini, vilages at Lemnos island, North Aegean Sea, • High solar and low wind potential (AREA C): Kumasas and Kandyllas, villages at Vagonia, Heraklion, Crete • High solar and high wind potential (AREA D): Kato Lefkos and Lefkos, Karpathos island, Dodecanese, South Aegean Sea. The selection of areas was as follows: Areas of the Greek Territory that are far away from urban centers, often experiencing the phenomenon of power outages throughout the year, areas of low touristic impact to avoid singularities in demands’ increment during the summer months, where distance between settlements could be three kilometers (max.) to help interconnection, population should be around 50 to 100 residents, while the existence of a meteorological station measuring solar radiation and wind speed is absolutely necessary, even if located in a third nearby settlement which does not interfere with an obstacle (i.e. mountain) between them. The study of the installation of the hybrid power generation system will begin with the area that present the worst set of data (AREA A). Precisely, we performed in-situ investigation in these two settlements, where 161 houses, 3 enterprises and 5 five public buildings were found. In addition, we meet all the permanent residents, obtaining therefore filled questionnaires. The required solar and wind data, as well as the maximum and minimum temperature values for area A, have been recorded by a nearby meteorological station (Department of Physics, University of Ioannina, Kalpaki, Greece). There is a wide range of meteorological data available (from June 2008 till December 2018) and the proximity of meteorological station ensures high accuracy of the measurements. Based on meteorological data, optimization depends on several scenarios that aim at covering the desired electrical load on a daily basis. These scenarios are based on factors such as 24Ώρες settlements coverage scenario (100% coverage), economic scenario (yearly coverage), environmental scenario and interconnection scenario. Analytically these scenarios are: a) 24Ώρες settlements coverage scenario (100% coverage): This scenario assures a continuous 24-Ώρες power supply to fully cover the desired loads. As far as the selected settlements are quite isolated and their population is low and very mature, the need a 24Ώρες energy supply is considered as essential. The optimal design of such a hybrid system should cover a steady electricity flow at the time its consumption, without allowing normal daily fluctuations of RES potential to affect power supply (Little et al., 2007). The same must also stand for unfavorable weather conditions, especially in the winter months due to lack of sunlight as well as low wind potential. Constant electricity flow will be achieved by using batteries that will not only be used as a backup energy system but also as a replacement for the electricity distribution network (Abdullah et al., 2010, Prodromidis & Coutelieris, 2014). b) Economic scenario: This scenario foresees non-continuous 24-Ώρες power supply with the most cost-effective installation and maintenance costs of the system as low as possible. Researchers have observed that certain renewable energy technologies such as photovoltaic panels are of low efficiency and that the initial cost and maintenance costs will be quite high (Little et al., 2007). The characteristics of renewable sources and the climatic conditions, influence the behavior and economics of renewable energy systems (Muselli et al., 1999, Tsikis & Coutelieris, 2010). In this scenario, the photovoltaic systems will be installed on the rooftops of the housing estates, as well as on some nearby land fields with the wind turbines, to assure costs lower than the upper limit, initially posed. The above restrictions on the installation area and the desired initial financial limit can be considered feasible in small settlements, even interconnection costs are also considered for a 25 year life span. Obviously, this scenario does not assure load coverage 24X7. c) Minimize excess energy scenario (partial coverage): This scenario minimize energy losses, with the main result being the lowest possible cost of installation, maintenance and operation of the system. It is called "Partial Coverage" because we use the maximum recorded electricity consumption value from our Electricity Provider and according to this scenario, we install the exact PV and WT numbers required to achieve the annual electricity value for the electrification of the settlements. This type of coverage is not 24X7, so some Ώρεςs of specific days (especially during winter) are out of electricity. As a matter of course, with this scenario there will be no electricity available for 24 Ώρεςs in the dwellings of the settlements and because of this, our system will remain uncover for some time. d) Environmental scenario: This scenario foresees the environmentally friendly nature of the system by reducing CO2 emissions. It is obvious, that the solar load generated by the hybrid system - wind turbine is the most important parameter for its sustainability. Essentially, the environmental scenario is a combination of the above two scenarios and forms part of them. Major result is the production of “green” energy and hence the reduction in carbon dioxide production, with direct consequence of reducing the carbon tax costs (Nordhaus, 2010). Another idea embedded in this scenario (but also applicable to other ones) is to put an on - switch in all permanent residents and an off-switch to non - permanent ones, prevailing that the use of electricity could be possible only when needed, while RES-based electricity is constantly produced throughout the whole year. e) Interconnection scenario: This scenario represents the process of electrical connection between two nearby settlements to exchange the excess electricity. The goal is not to leave any of the two neighboring settlements without electricity throughout 24 Ώρεςs per day. An interconnected network for delivering electricity from producers to consumers consists of power generation units, transmission lines that carry power from distant sources to demand centers, and distribution lines that connect individual customers (Kaplan, 2009). In our case, producers and consumers are the two nearby settlements which produce and consume the electric power simultaneously, while the transmission lines will carry the electric power from one settlement to the other, depending on the everyday need. The distance that the electricity would be transferred will be no more than three kilometers, to assure low power losses. Apparently, the cost of installing and maintaining the interconnection lines between the settlements should be taken into account in the general installation cost of the system. As presented in Table 1, residents are very positive to the prospect of electrical cooperation with the neighboring settlement. In this study, a methodology for installing an autonomous off-grid hybrid PV/wind system with battery storage for small-scale settlements is proposed. This methodology is based on selection criteria regarding RES-potential and meteorological, geographical and geospatial, demographic and land-use data, while several scenarios for the selection of specific PV/wind systems are also considered. Secondly, an optimization procedure is performed to reduce costs and maximize the load’s coverage. The evaluation of the optimal scenario will transform the proposed methodology to a decision-making and finally an energy-policy tool for designing and implementing RES-based off-grid power plants. The method applied in Greece, concluded the following: • Four areas and eight small settlements have been selected to satisfy all the combinations of solar and wind data i.e. higher and lower values • It is able to electrify small settlements using exclusively hybrid pv/wind system. • The acceptance of the resident was very encouraging. • Residents are positive to the interconnection between neighboring settlements. The main optimization norm is the continuous 24X7 load coverage, despite the relatively high costs. Decrease of energy demands by applying well-known practices, use of environmental–friendly power production methods and wide social acceptance and cooperation will allow for a new perspective in energy distribution, thus this methodology can be also a very important tool for energy policy makers, especially when work on small settlements