## 4 Discussion  
The first case study was only aimed at showing how RESTcreen is powerful, even mixing different renewable technologies in one single power plant, optimizing the project on the base of the location characteristics. The second case study provided more evidence, reported in Table 9. The different outputs of the two installations (i.e., wind turbine vs. photovoltaic) are provided. Figure 11: Financial analysis chart (screenshot by author using RESTcreen). \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Wind Turbine** & **Photovoltaic** \\ \hline Location & TORONTO & \\ \hline Capacity & & 1000 kW \\ \hline Project life & & 25 yr \\ \hline Electricity export rate & & 100 CA\$/MWh \\ \hline Electricity & 3197 MWh & 1218 MWh \\ \hline Gross annual GHG emission reduction & 302 tCO\({}_{2}\) & 120 tCO\({}_{2}\) \\ \hline Total initial costs & 2,309,703 CA\$ & 1,920,278 CA\$ \\ \hline Pre-tax IRR-equity & 31.1\% & 7\% \\ \hline Equity payback period & 3.5 yr & 16.7 yr \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Wind turbine vs photovoltaic in RESTcreen. It is possible to notice that, starting from a common baseline (same location, same power plant capacity, same project life and same evaluation for electricity export rate), that the electricity produced by the two power plants is sensibly different; in fact, the wind turbine system is much more efficient than the photovoltaics. Due to its higher efficiency in producing electricity, the correspondent gross annual emission reduction of greenhouse gases is bigger for the wind turbine with respect to the photovoltaic case. Findings emerged from our investigation can represent useful insights for policy makers. Specifically, besides looking at policy of direct regulations, other policy instruments that can indirectly support deployment of renewable energy resources in the long term should be adequately taken into account. These indirect strategies can be in the form of environmental taxes or of emission permits for energy produced by non-renewable sources, as well as the removal of subsidies given to fossil fuel generation [34]. Moreover, even though the total initial cost for the photovoltaic power plant is lower than for the wind turbine installation, it can be inferred from the financial indicators that the investment is much more convenient for the wind turbine project, which is able to cover its initial costs in a time 14% of the total lifetime; on the other side, with photovoltaics installation you will cover the costs after 70% of the project lifetime. Another aspect for policy makers to consider is looking at the financial issues that might prevent investment decisions. In this perspective, enhancing the green finance--i.e., the financing of investments that provide environmental benefits in the broader context of environmentally sustainable development [35]--may significantly contribute to guaranteeing capital flow in renewable energy sectors [36] so as to enhance the sustainability of the overall financial system [37] as well as to improve corporate planning strategies [38]. Overall, the aim of this study is not to evaluate which renewable technology is more affordable or efficient (it is very easy to find wind turbine for high-capacity systems and, on the contrary, projecting photovoltaic installation is usually aimed at small-capacity systems, such as houses), but to understand how the RESTcreen software could be successfully adopted in decision-making processes in an early stage (e.g., pre-feasibility analysis), to effectively exclude inconvenient choices under determined constraints. From this perspective, a technique for optimizing a renewable energy network is developed using RESTcreen software tool. It is built to maximize the size of an integrated hybrid energy system in buildings. Case studies for a single and an integrated renewable energy program may research the efficiency of the methods [39].