# Investigation of a Solar-Driven Organic Rankine Cycle with Reheating
## 3 Results and Discussion
### Financial Performance  
The last step in the present work is the presentation of the financial analysis of the studied solar-fed ORCs. Figure 14 depicts the simple payback period of the reheat ORC case for different scenarios. It can be said that the lower electricity capacity reduces the SPP, while the optimal saturation temperature is in the range of 120-140 \({}^{\circ}\)C. More specifically, the global minimum SPP is found for 10 kW and 120 \({}^{\circ}\)C at 9.63 years. For higher capacities, the optimum saturation temperature presents a small increase according to the results.  
Figure 15 depicts the SPP for the simple ORC and it is obvious that the global minimum value is found for 10 kW and 90 \({}^{\circ}\)C saturation temperature at 10.84 years. For all the capacities, the SPP is minimized for 90 \({}^{\circ}\)C, which is an interesting result because it is significantly lower than the respective optical values for the reheat system (120-140 \({}^{\circ}\)C). Moreover, an interesting result is that for both cases, the minimum capacity is the best one according to the SPP criterion.  
Figure 11: Monthly system efficiency and electricity yield for the optimum case of the reheat ORC case according to system efficiency maximization (\(T_{sat}=140\)\({}^{\circ}\)C \(-\)\(P_{d}=25\) kW).  
Figure 12: Yearly system efficiency for the simple ORC case for different combinations of saturation temperature levels and electricity capacities.  
Figure 13: Monthly system efficiency and electricity yield for the optimum case of the simple ORC case according to system efficiency maximization (\(T_{sat}=90\)\({}^{\circ}\mathrm{C}-P_{el}=25\) kW).  
Figure 16 and 17 illustrate the NPV of the examined investments for the heat and simple scenarios, respectively. The global maximum NPV for the reheat system is found for 15 kW capacity and 130 \({}^{\circ}\)C saturation temperature at 68 k\(\ell\). On the other hand,  
Figure 14: Simple payback period for the reheat ORC case for different combinations of saturation temperature levels and electricity capacities.  
Figure 15: Simple payback period for the simple ORC case for different combinations of saturation temperature levels and electricity capacities.  
the global maximum NPV for the simple case is found for 10 kW and 90 \({}^{\circ}\)C saturation temperature at 44 k\(\ell\).  
Figure 16: Net present value for the reheat ORC case for different combinations of saturation temperature levels and electricity capacities.  
Figure 17: Net present value for the simple ORC case for different combinations of saturation temperature levels and electricity capacities.  
At the end of this section, the optimal cases according to the NPV maximization are summarized in Table 4. It can be said that all the indexes are better for the reheat ORC, compared to the simple ORC. Thus, it is clear that the suggested system is an efficient and viable one compared to the conventional scenario. Thus, it is suggested that the reheat ORC is an attractive choice for solar-driven ORCs. It is essential to state that for these cases, system efficiency is 6.98% for the reheat case and 5.09% for the simple cases, presenting an enhancement of 37.1%. The NPV is 68 k\(\xi\) for the reheat case and 44 k\(\xi\) for the simple case, something that indicates 24 k\(\xi\) net gain from the investment in the reheating system.