## 1 Introduction  
Increasing greenhouse gas emissions around the world has become a matter of paramount importance in today's energy production scenario. A reduction of carbon dioxide (CO\({}_{2}\)) emissions resulting from energy production is a common objective in industry and research. The conversion of CO\({}_{2}\) into artificial methane (CH\({}_{4}\)) by catalytic reaction of thermodynamic methanation is a sustainable technique currently gaining attention in the solar to methane (StM) chain technical community. Electrical energy from renewable sources can be converted into storable chemical energy. A potential solution for solar energy storage is the transformation of solar energy into synthetic chemical energy. The transformation can be accomplished by a Sabatier reaction. In this reaction, a catalytic methanation is performed by the combination of carbon dioxide (CO\({}_{2}\)) and hydrogen (H\({}_{2}\)) produced from water splitting and possibly from a renewable energy source. Highly efficient concentrator photovoltaic (CPV) modules (as a renewable energy source) and electrochemical (EC) cells for H\({}_{2}\) production are compulsory for efficient conversion of solar energy to H\({}_{2}\) gas [1]. A CPV system with the highest efficiency is one of the crucial aspects in the development of a modernized solar system. One of the most up-and-coming technologies in the conversion of solar energy to chemical energy is the combination of solar energy to H\({}_{2}\) and CO\({}_{2}\) gases in the methanation process. This synthetic natural gas could be substituted in the current gas grid sector since CH\({}_{4}\) can be stored effectively. According to the measurements done by the state of the art, the best efficiencies in the various studies were achieved to 90% for the capture of CO\({}_{2}\) from off-gas [2], 80% for water electrolysis [3], and 80% for CO\({}_{2}\) methanation [4]. The combination of sunlight-derived hydrogen and CO\({}_{2}\) to store solar energy in the chemical form of CH\({}_{4}\) with higher efficiency is still in the development stage. Therefore, in this study, the produced hydrogen from the efficient CPV modules under outdoor conditions was directly applied to the methanation system, and the conversion efficiency and power consumption of solar to methane were considered and evaluated. Figure 1 shows the fundamental StM concept of our system. As shown in Figure 1, sunlight was captured by highly efficient CPV modules and transformed into high-grade solar energy. The produced electrical energy was utilized in the water splitting system (which consisted of EC cells and DC/DC converters) to convert to H\({}_{2}\) and oxygen. The proton exchange membrane (PEM) electrolysis method is currently attracting researchers' attention as a result of its higher resilience, high functioning current densities, authentic gas generation, H\({}_{2}\) manufacturing at a higher pressure, and compact structure. The process of mixing H\({}_{2}\) and CO\({}_{2}\) gases occurs while producing CH\({}_{4}\) within the reactors. The energy conversion efficiency from solar to hydrogen and composition of produced methane can be unique depending upon the types of water splitting system, reactors, and catalysts. The conversion of CO\({}_{2}\) to CH\({}_{4}\) in the presence of a catalyst (usually a Ni-based catalyst) and at a temperature of 250 to 300 \({}^{\circ}\)C has the characteristics of a thermochemical or thermocatalytic methanation [5]. The procedure of hydrogenating CO\({}_{2}\) to get synthetic CH\({}_{4}\) natural gas is mostly referred to as the Sabatier process. A highly effective catalyst is required for the direct conversion of CO\({}_{2}\) to CH\({}_{4}\) with a reasonable conversion rate. The catalyst also enables selectivity at specified lower temperatures while providing no evidence of transitional conditions [6; 7].