# Potential of Photovoltaic Generation in the Putumayo Department of Colombia
## 3 Results
### Calculation and Analysis of Solar Radiation Data for Different Regions and Stations
This database reports solar irradiance values on horizontal surface every half hour from 1998 to 2015 and with a spatial resolution of 4 km by 4 km. In addition, NASA's data series reporting monthly average daily irradiance data with a resolution of 0.5\({}^{\circ}\) by 0.5\({}^{\circ}\) (approximately 55 km by 55 km) were taken. These series have data for the period 1981 to 2017. With the above data, the irradiation values were calculated for each zone respectively, which can be seen in Figure 6a for NREL and Figure 6b for NASA. As clarification due to NASA's resolution, the data covers areas with more than one station. As can be seen in Figure 6b, the Villagarzon, Mocoa, Primavera, and Michoacan stations are less than 55 km away from each other, so they are represented by the same irradiation value. These data are not reliable since the stations belong to both the Andean and Andean-Amazon regions,  
Figure 4: Results of data from IDEAM weather stations: (**a**) Average hours of sunshine per month; (**b**) Average daily solar irradiation per month. Figure 5: Location of IDEAM’s weather stations with solar brightness data in the department of Putumayo. which have different geographic and climatic conditions, which as indicated in Figure 6a,b, have different irradiation values. With the monthly irradiation data \(G_{dm}(0)\) from NREL and NASA, daily averages of annual irradiation \(G_{da}(0)\) were calculated and the error and adjustment statistics presented in Table 2 were obtained. From these values, it is possible to identify that the NASA data does not fully match the NREL data, since the NASA remote stations cover large regions with several NREL stations. For the Encano station, for example, there is the least statistical error when comparing the values reported by both databases, which indicates that NASA's remote sensors are actually taking radiation values from that site and can differentiate them from the nearby region where the other Andean zone databases are located. However, for the Villagarzon, Mocoa, Primavera, and Michoacan stations, NASA reports the same radiation value, 4.37 kWh/m2 day even though two of them are in the Andean zone and the other two in the Andean-Amazon, while NREL establishes different and lower values. This means that NASA's remote sensors are unable to differentiate these zones. The adjustments between both bases are adequate for Villagarzon, Mocoa and Primavera (errors less than 3%), but not so much for Michoacan, where higher values of the statisticians are \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Region**} & \multirow{2}{*}{**Station Area**} & **NREL \(G_{da}\)(0)** & **NASA \(G_{da}\)(0)** & **MBE** & \multirow{2}{*}{**MPE \%**} & **RMSE (kWh/m2 day)** & **Statistic t** \\  & & **(kWh/m2 day)** & **(kWh/m2 day)** & **(kWh/m2 day)** & & **(kWh/m2 day)** \\ \hline \multirow{4}{*}{Amazon} & Leguizamo & 4.75 & 4.46 & \(-\)0.29 & 6.13 & 0.32 & 7.64 \\  & Tagua & 4.84 & 4.46 & \(-\)0.38 & 7.87 & 0.39 & 12.12 \\  & Tres-Esquina & 4.73 & 4.33 & \(-\)0.39 & 8.40 & 0.40 & 26.24 \\  & Valparaiso & 4.85 & 3.94 & \(-\)0.90 & 18.44 & 0.92 & 15.97 \\  & Umbria & 4.52 & 3.76 & \(-\)0.76 & 16.68 & 0.78 & 15.67 \\ \hline \multirow{2}{*}{A Andean-Amazon} & Villagarzon & 4.21 & 4.37 & 0.16 & \(-\)4.43 & 0.35 & 1.67 \\  & Mocoa & 4.08 & 4.37 & 0.29 & \(-\)7.96 & 0.47 & 2.53 \\ \hline \multirow{2}{*}{A Andean} & Primavera & 4.02 & 4.37 & 0.35 & \(-\)9.84 & 0.55 & 2.73 \\  & Michoacán & 3.66 & 4.37 & 0.71 & \(-\)21.94 & 0.88 & 4.52 \\ \cline{1-1}  & El encano & 4.24 & 4.12 & \(-\)0.11 & 2.51 & 0.28 & 1.47 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of irradiance values (\(G_{da}\)) calculated from NREL and NASA databases. Figure 6: Results of daily monthly averages of solar irradiation from remote sensor databases: (**a**) NREL database; (**b**) NASA database. presented. For clarification, the Michoacan station is in the Andean region in which there are a variety of microclimates that are presented by the thermal floors of the mountain range.