## 5 Discussion and Analysis  
The system of Equations (1)-(16) has been numerically solved in finite-difference formulation for the energy conversion process in the hybrid system of PV-Thermal solar collector, ORC with cooling capability employing nanofluids; Al\({}_{2}\)O\({}_{3}\), CuO, Fe\({}_{3}\)O\({}_{4}\) and SiO\({}_{2}\) at different concentrations and water as base heat transfer fluid. Table S1 presents the thermophysical properties of nanofluids used in this study. In the following sections, the predicted results are presented under different inlet conditions, such as solar insolation, heat transfer fluid flow rates from the PV-Thermal, heat transfer fluid temperatures and various nanofluids at different volumetric concentrations. In the numerical simulation, 100 PV solar panels were assumed with 300 watts per each PV solar panel. Solar radiations were taken as 500, 750, 1000 and finally, 1200 w/m\({}^{2}\) and heat transfer fluid temperature varied from 176 \({}^{\circ}\)F to 212 \({}^{\circ}\)F. As reported in [PERSON] and [PERSON] [7], calculations using Equations (1)-(4) yielded the efficiency of the PV solar panels used in this study varies between 19% and 23% depending on the solar radiation that varies between 500 w/m\({}^{2}\) to 1200 w/m\({}^{2}\). These values will be taken and considered as base values for comparison between the hybrid system efficiency of the PV-Thermal and ORC system and that of the PV solar panels. The heat transfer fluid flow rate circulating in the loop, driving the waste heat boiler of the ORC between 8.89 GPM (4208 lb/hr) to 22.6 GPM (10550 lb/hr) at temperatures varied between 176 \({}^{\circ}\)F to 212 \({}^{\circ}\)F. For comparison purposes, the pressure in the refrigerant mixture cycle of the ORC was kept constant between the waste heat boiler and the condenser at 133 psi and 55 psi, respectively. The boiling temperature of the refrigerant mixture was at -28 \({}^{\circ}\)F. The refrigerant mixture exits the waste heat boiler to the vapor turbine at vapor saturation conditions. Appropriate heat exchanger and vapor turbine efficiency values were used for the ORC cycle calculations as well as the cooling capacity. The Carnot cycle efficiency of the ORC conditions was 27.38% and on average, the ORC efficiency was 8.3% using the environmentally sound quaternary refrigerant mixture composed of R152a, R245 fa, R125, and R1234 fy. In the following sections, the impact of the solar radiations on the Hybrid system performance, and cooling/freezing effect produced as defined by Equation (9) and the efficiency of the hybrid system composed of the PV solar panel, PV-Thermal and the ORC, as calculated by Equation (11) are analyzed and discussed. The aim of this study was to illustrate the role of nanofluids in the enhancement of the Hybrid system efficiency and the cooling effect produced over that of the PV solar panels and ORC, respectively. The hybrid system efficiency calculated by Equation (11) is plotted in Figures 3-6 to illustrate the impact of solar radiations and the different nanofluids and water as the heat transfer fluid on the hybrid system performance of the PV-Thermal solar panels. It is quite evident from the results presented in these figures that the nanofluid CuO has the highest efficiency among the different nanofluids and water. It is also evident from these figures that the higher the nanofluid flow temperature, the higher the hybrid system efficiency. This can be interpreted as pointed out by [18; 19; 20] that convective heat transfer performance of suspended nanoparticles outstandingly increases the heat transfer thermal capacity of the base-fluid and the nanofluids have higher heat transfer coefficients than those of the base-fluids for the same Reynolds number. Figure 4: Hybrid system efficiency for Nanofluid Fe\({}_{3}\)O\({}_{4}\) at different temperatures and 20% volumetric concentration. Figure 3: Hybrid system efficiency for Nanofluid SiO\({}_{2}\) at different temperatures and 20% volumetric concentration.