# Photovoltaic Prediction Software: Evaluation with Real Data from Northern Spain
## 2 Methodology
### Pygis  
The Photovoltaic Geographical Information System (PVGIS) provides a map-based inventory of solar energy resource and an assessment of electricity generation from photovoltaic systems in Europe, Asia, Africa, and South America. The database includes monthly and yearly average values of the global irradiation on horizontal and inclined surfaces, as well as climatic parameters needed for an assessment of the potential PV electricity generation [14; 15]. With the following applications, it is possible to choose between databases collected by satellite that includes data from 2005 to 2016: SARAH, NREL, CMSAF, ECMWF, and COSMO-REA6. It uses an interpolation of data models for geographic resolution.  
Using PV-GIS, the PV facility can be described by selecting the type of solar tracking system, its integration or otherwise within the buildings, installed power, system performance, and PV panel technology (Si Crystalline CdTe, CIS o CIGS). PVGIS provides daily and monthly average global irradiation data and daily and monthly average PV power production. It can also be used to optimize the angles of orientation of the PV panels and their tilt.  
The simplicity and free use of PVGIS mean that it is frequently used for initial energy estimations of PV facilities. The databases are widely implemented in Europe, Africa, and Asia with regular updates, and their reliability has been demonstrated in a large number of scientific papers [16; 17; 18; 19; 20].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **System 1** & **System 2** & **System 3** \\  & **(Palencia)** & **(Torquemada)** & **(Los Balbases)** \\ \hline Sea Level (m) & 740 m & 742 m & 800 m \\ Longitude & 4\({}^{\circ}\)30\({}^{\prime}\) W & 4\({}^{\circ}\)19\({}^{\prime}\) W & 4\({}^{\circ}\)3\({}^{\prime}\) W \\ Latitude & 42\({}^{\circ}\)0\({}^{\prime}\) N & 42\({}^{\circ}\)2\({}^{\prime}\) N & 42\({}^{\circ}\)12\({}^{\prime}\) N \\ \hline Panel model & Fotona 180D & BP-7185S & Sunport 72M \\ \hline V\({}_{\text{max}}\)(V) & 36.8 & 36.5 & 35.89 \\ I\({}_{\text{max}}\) (A) & 4.89 & 5.1 & 7.81 \\ W\({}_{\text{P}}\) (W) & 180 \(\pm\) 1.3\% & 185 \(\pm\) 2.5\% & 280 \(\pm\) 3.0\% \\ Performance (\%) & 15\% & 14–16\% & 14\% \\ Number of panels & 216 & 546 & 51 \\ Number of groups & 18 & 39 & 3 \\ V\({}_{\text{group}}\) (V) & 441 & 511 & 610 \\ Facility Power (kW) & **38.88** & **101.01** & **14.28** \\ \hline Inverter model & SMA: SMC 7000 TL & Ingeocom Sun 100 &
\begin{tabular}{c} SMA: Sunny Boy \\ 4200 TL HC \\ \end{tabular} \\ \hline Maximum power (kW) & 7 & 100 & 4.4 \\ Number of inverters & 6 & 1 & 3 \\ V\({}_{\text{cc}}\) (V) & 700 & 405–750 & 750 \\ Loc (A) & 22 & 286 & 22 \\ V\({}_{\text{ca}}\) (V) & 230 & \(3\times 400\) & 230 \\ I\({}_{\text{ca}}\) (A) & 31 & 187 & 19 \\ Performance (\%) & 98 & 96.8 & 96 \\ \hline Sun Tracking System & Fixed & 1-axis & 2-axis \\ \hline Tilt angle or sun & \multirow{2}{*}{20\({}^{\circ}\)} & \multirow{2}{*}{15\({}^{\circ}\)/55\({}^{\circ}\)} & \(-\)130\({}^{\circ}\)/130\({}^{\circ}\) \\ tracking limits & & & 0\({}^{\circ}\)/80\({}^{\circ}\) \\ Orientation & \(\text{South}/180^{\circ}\) & \multirow{2}{*}{South/180\({}^{\circ}\)} & \\ \end{tabular}
\end{table}
Table 2: Technical specifications of panels and inverters used in the PV facilities under study (System 1, System 2, and System 3).