Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser Review of solar photovoltaic and wind hybrid energy systems for sizing strategies optimization techniques and cost analysis methodologies Faizan A. Khan a , Nitai Pal b , Syed.H. Saeed c a Department of Electrical Engineering, Integral University, Lucknow, India b Department of Electrical Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, India c Department of Electronics & Communication Engineering, Integral University, Lucknow, India ARTICLE INFO Keywords: Renewable energy Sizing schemes Optimization Techniques and cost analysis ABSTRACT Electrical energy becomes necessary for human being. Generation of electrical energy mostly depends on fossils fuel, they are limited in nature and also responsible for environmental pollution. Renewable energy resources provides a better alternative for future,In comparison to conventional energy resources economical aspect is a major issue of renewable energy sources with the feasibility and efficiency. These limitations are tried to overcome by deployment hybrid renewable energy resources. There are certain criteria to analyze and imple- ment the sized, optimized and cost efficient system. This paper focus on hybrid energy systems based on solar photovoltaic (PV) and wind resources. This paper shed lights on various parameters of economic feasibility, sizing strategies with logical advancements to enhance their utilization, future prospects, and their arrangement. Strategies to develop an effective storage system is also presented here.A brief review on developments in op- timization techniques, reliability index and cost analyzing techniques for hybrid renewable energy systems are also presented. 1. Introduction Growing consumption of fossil based energy resources necessitated an insistent seek out for substitute resources. Due to ecological reasons renewable energy resources have considered as better choices. Solar Photovoltaic and wind energy are recognized as most encouraging and feasible sources, it is widely known that solar and wind energy re- sources are never ending and their transformation into power are without contamination, and their accessibility is additionally at no cost [1]. One of major issue for humanity is increase in environmental pollution. [2] After the discoveries of alternative resources of electricity generation sources the deployment of solar photovoltaic and wind en- ergy system has become increasingly more popular [3]. There are little symptoms that immediately required to change for global energy sce- nario,the era of fossil fuels is a long way to over, however their dom- inance still reduced but it is not affordable to wait for taking action againsts the movement volved in weather alternation [101]. Worldwide Governments have started to shift their regulations and policies to en- courage the utilization of renewable energy resources by including the provision of improving the capability of renewable energy resources and energy preservation strategy [4,101]. It becomes difficult to pro- viding reliable and persistent supply of energy as solar photovoltaic and wind energy resources are dependent on whether conditions. This issue can be fathomed by a reasonable arrangement of energy storage in addition to solar photovoltaic and wind energy resources [5]. Solar Photovoltaic and wind energy system individually utilized as stand alone or grid connected with low efficiency while cumulative ar- rangement of solar PV and wind energy resources are considered as hybrid energy system [9]. Most significant feature of a hybrid renew- able energy resource is utilization of many nonconventional energy sources to enhance the effectiveness of system and economic restric- tions [6]. The solar Photovoltaic and wind energy resources operates in simultaneous and sequential manner, in first case, both generate energy at the same time while in second one electricity is generated alter- natively [10]. Solar Photovoltaic and wind energy resources attracts various researchers to pursue several methodologies for unit sizing and optimization of hybrid energy system based on Photovoltaic and wind resources [11,128–130]. The variation in output of solar PV and wind energies in general not similar as load demand therefore reliability analysis is required for designing and function of hybrid energy systems for standalone application. [12]. In past few decades study of hybrid arrangement of energy resources renewable in nature have attracted noteworthy attention, Borowy et al. [12] have introduces loss of load probability (LLP) theory for determining Optimum level of sizing for solar photovoltaic and wind based hybrid system of energy generation. Shrestha et al. [13] discussed a technique based on energy generation simulated for optimum sizing and designing of hybrid system of energy based on solar photovoltaic and wind energy resources. An analysis for sizing and optimization of hybrid system of renewable energy had been performed by Kellogg et al. [14] determining probability of loss in power supply which is designated as LPSP (Loss of Power Supply Pos- sibility) technique and levelised cost of energy (LCE) methodology. https://doi.org/10.1016/j.rser.2018.04.107 Received 20 December 2017; Received in revised form 2 March 2018; Accepted 21 April 2018 Renewable and Sustainable Energy Reviews 92 (2018) 937–947 1364-0321/ © 2018 Elsevier Ltd. All rights reserved. T