# Solar Potential in Saudi Arabia for Southward-Inclined Flat-Plate Surfaces
## 2 Materials and Methods  
### Data Collection  
Hourly values of the direct, H\({}_{\text{b,0}}\) (in Wm\({}^{-2}\)), and diffuse, H\({}_{\text{d,0}}\) (in Wm\({}^{-2}\)), horizontal solar radiation components were downloaded from the PV--Geographical Information System (PV-GIS) tool [31] using the latest Surface Solar Radiation Data Set--Heliostat (SARAH) 2005-2016 data base (12 years) [32; 33]. This platform has been chosen for retrieving solar radiation data through a user-friendly tool that provides data for any location in Europe, Africa, Middle East including Saudi Arabia, central and southeast Asia and most parts of the Americas. Nevertheless, the platform provides solar maps for Europe, Africa, Turkey and central Asia only. The methods used by PV-GIS to calculate solar radiation from satellite are described in various works [30; 34; 35]. A set of 82 sites was arbitrarily chosen in order to cover the whole area of Saudi Arabia. Table 1 gives the names and the geographical coordinates of these sites, while Figure 1 shows their location in the map of the country. It should be noted here that the selection of the sites was based on the \"inhabited\" criterion (i.e., urban areas, 57 out of a total of 82); other 25 sites were added to the 57, but refer to uninhabited regions (sites with no names in Table 1). For this reason, the dispersion of the 82 sites is not uniform within Saudi Arabia. There should also be mentioned here that the downloaded hourly solar horizontal radiation values refer to those from an unobstructed horizon (no effect of the ground on solar radiation) by not selecting the \"calculated horizon\" option in the PV-GIS tool.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \# & **Site** & **\(\boldsymbol{\varphi}\) (\({}^{\circ}\) N)** & **\(\boldsymbol{\lambda}\) (\({}^{\circ}\) E)** \\ \hline
1 & Dammam & 26.42 & 50.09 \\
2 & Al Jubail & 26.96 & 49.57 \\
3 & Ras Tanura & 26.77 & 50.00 \\
4 & Abqaiq & 25.92 & 49.67 \\
5 & Al Hoftuf & 25.38 & 49.59 \\
6 & Arar & 30.96 & 41.06 \\
7 & Sakaka & 29.88 & 40.10 \\
8 & Tabuk & 28.38 & 36.57 \\
9 & Al Jawf & 29.89 & 39.32 \\
10 & Riyadh & 24.71 & 46.68 \\
11 & Al Qassim & 26.21 & 43.48 \\
12 & Hafar Al Batin & 28.38 & 45.96 \\
13 & Buraydah & 26.36 & 43.98 \\
14 & Al Majma’ah & 25.88 & 45.37 \\
15 & Hail & 27.51 & 41.72 \\
16 & Jeddah & 21.49 & 39.19 \\
17 & Jazan & 16.89 & 42.57 \\
18 & Mecca & 21.39 & 39.86 \\
19 & Medina & 24.52 & 39.57 \\
20 & Taif & 21.28 & 40.42 \\
21 & Yanbu & 24.02 & 38.19 \\
22 & King Abdullah Economic City & 22.45 & 39.13 \\
23 & Najran & 17.57 & 44.23 \\
24 & Abha & 18.25 & 42.51 \\
25 & Bisha & 19.98 & 42.59 \\
26 & Al Sahmah & 20.10 & 54.94 \\
27 & Thabloten & 19.83 & 53.90 \\
28 & Ardah & 21.22 & 55.24 \\
29 & Shaybah & 22.52 & 54.00 \\
30 & Al Kharkhir & 18.87 & 51.13 \\
31 & Umm Al Melh & 19.11 & 50.11 \\
32 & Ash Shalfa & 21.87 & 49.71 \\
33 & Oroug Bani Maradh Wildlife & 19.41 & 45.88 \\
34 & Wadi ad Dawasir & 20.49 & 44.86 \\
35 & Al Bade Al Shamali & 21.99 & 46.58 \\
36 & Houtat Bani Tamim & 23.52 & 46.84 \\
37 & Al Duwadimi & 24.50 & 44.39 \\
38 & Shaqra & 25.23 & 45.24 \\
39 & Afif & 24.02 & 42.95 \\
40 & New Muwayh & 22.43 & 41.74 \\
41 & Mahd Al Thahab & 23.49 & 40.85 \\
42 & Ar Rass & 25.84 & 43.54 \\
43 & Uglat Asugour & 25.85 & 42.15 \\
44 & Al Henakiyah & 24.93 & 40.54 \\
45 & Ar Rawdah & 26.81 & 41.68 \\
46 & Asbtar & 26.96 & 40.28 \\
47 & Tayma & 27.62 & 38.48 \\
48 & Al Khanafah Wildlife Sanctuary & 28.81 & 38.92 \\
49 & [PERSON] & 26.92 & 38.04 \\
50 & Altubaiq Natural Reserve & 29.51 & 37.23 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The 82 sites arbitrarily selected over Saudi Arabia to cover the whole area of the country; \(\varphi\) is the geographical latitude, and \(\lambda\) the geographical longitude in the WGS84 geodetic system. The “unnamed” sites refer to those away from known locations.