With rising demand of energy crisis, the extension of the grid, only with the non-renewable energy sources, has resulted to an end. As a result, the engineers from energy and power generation sector have become conscious for searching an alternate option, which includes the renewable source of energy like solar, wind, small hydro, geothermal, biomass, and ocean as economic, sustainable, and atmosphere pleasant alternative for the conventional source of energies. The inconsistencies in the accessibility of renewable sources every time throughout the year have led to a great expansion in the field of hybrid renewable energy system (HRES). In recent years, several researches have been reported on architecture, operation, and optimization of HRES in response to rising demands. This paper presents an analytical review of various issues related to HRES-based power generation. An overview of different architectures, performances, and reliabilities of hybrid energy system taking optimization into consideration has been presented. Reliability optimization adopted and reported in the studies which include sizing, cost, net present value, etc., of the system components is reviewed. Various software tools that enable evaluation and optimization of performance, reliability, and other parameters for hybrid system configurations are discussed in detail. The challenges, accessibility, and domain of future research in terms of optimization have also been identified.