## 4 Results
### On-Site Power Generation  
Figure 13 shows the estimated monthly electricity generation of the SPVS of 50 kWp projected by HOMER Pro. The electrical load of the building was 97,958 kWh/year, whose monthly distribution can be seen in Figure 5. The total annual electric energy delivered by SPVS was 66,590 kWh where 48,497 kWh served to feed the building and the remaining 18,093 kWh were introduced into the electric power grid. This last amount is the excess energy produced by the SPVS when the building's electrical load is already covered [62]. The energy purchased from the grid during one year for the building's operation was 47,080 kWh. The month of July showed the minimum reduction of 44.20% in the use of energy purchased from the grid compared with the baseline modeling. October showed the highest reduction with 59.96%. The average monthly reduction was 51.98%.  
Figure 14 shows the distributions of the annual hourly electrical power. As can be seen in the figure, the distribution of the power from the SPVS (output power converter) and electric power grid to cover the electrical load can be clearly observed. It should be emphasized that the operation of the SPVS is given according to the following cases. First, when there is a high solar resource and certain power consumption of the building at a specific time during daytime, the power of the converter could exceed this consumption and the surplus is introduced into the grid. The highest levels of power injection to the grid take place between 11:00 and 17:00, given that the electrical load is completely covered. In contrast, if there is a low solar resource and certain power consumption of the building in a certain time during daytime, the power of the converter is completely injected into the building and the difference to complete the load is taken from the grid. During the nighttime, the power consumption of the building is completely taken from the grid.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Energy Saving Scenario** & **Investment Cost** & **Unit** & **Total** & **Payback** \\ \hline Static shading devices & & & & \\ \hline Overhangs and vertical fins from aluminium & From \$118.76/m\({}^{2}\) & 211 m\({}^{2}\) & From \$25,058.36 & 47.16 years \\ \hline TrpLoE & & & & \\ \hline Triple glazing (6 mm) with double low emissivity films and aluminum profile & From \$174.80/m\({}^{2}\) & 310 m\({}^{2}\) & From \$54,188.00 & 103.8 years \\ \hline Active measures & & & & \\ \hline Changing the cooling setpoint temperature & - & - & - & \\ \hline Mini split 12,000 & & & & \\ BTU/h: from & & & & \\ \(\$500.00\)/unit & & & & \\ Mini split 18,000 & & & & \\ BTU/h: from & 10 & & & \\ Replacement of obsolete air-conditioners & \$700.00/unit & 7 & & \\ with their higher efficiency equivalent & Floor/ceiling split & 6 & & \\ \(\$600\) & \$1000.00 & 2 & & 63.7 years \\ \(\$950\) & \$1000.00/unit & & & \\ Floor/ceiling split & & & & \\ \(\$600\) & \$1000.00 & \(\$1000.00\)/unit & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: _Cont._Furthermore, since the building does not operate on weekends, the power delivered by the SPVS is almost entirely injected into the grid. The results show that there are a significant number of hours of daytime per year that present the first case of operation.  
The initial capital cost of the SPVS was USD$72,222.00 with an operation and maintenance cost of USD$3211.00. This last cost is related to the payment of energy purchased from the grid. In the present work, the SPVS was analyzed for one year of operation and the costs of assembly and installation of the system had not been considered.