# Solar Potential in Saudi Arabia for Flat-Plate Surfaces of Varying Tilt Tracking the Sun
## 5 Discussion  
Three innovations appeared in the present study. (i) For the first time, solar maps for Saudi Arabia of the solar energy received on inclined flat surfaces continuously tracking the sun were derived. (ii) A universal curve (nomogram) of CF in relation to \(\rho_{\rm r}\) was derived for this case, as in [1,2]. (iii) Accommodation of most sites within the mean \(\rm RAH_{g}\pm 1\sigma\) band was found in both relations CF vs. \(\rm RAH_{g}\) and \(\rho_{\rm r}\) vs. \(\rm RAH_{g}\); the last two statements remain to be confirmed at other locations in the world to constitute universality.  
On the basis of the adopted methodology, we here provide some guidelines for interested solar energy scientists and/or solar energy entrepreneurs. The steps of the guidelines are the following.  
* If a solar radiation station exists in the area, hourly or daily values of the solar global horizontal radiation are collected for a climatological period of 10 years at least.
* If no solar radiation exists, then data from relevant websites (e.g., BSRN, GEBA, PV-GIS, ARM) are obtained.
* In the extreme case that this option is not possible, use of a solar energy model can be made to derive the anticipated data from other available variables (e.g., from meteorological parameters as the Meteorological Radiation Model-MRM does [44]).
* Transposition of the selected data from horizontal to inclined planes that track the sun takes place by setting the tilt angle always equal to \(90^{\circ}-\gamma\). The transposition is achieved by selecting the desired model (the L-J model is sufficient). It is recommended that a near-real ground-albedo value is used in these calculations; if knowledge of this value is not available for the site, use of the nomogram of Figure 11 is made to correct the solar energy values derived.
* Annual solar energy sums for the inclined planes are calculated.
* Monthly solar energy sums are estimated, and a regression line can be derived that serves as guideline for estimating the expected solar energy on flat planes.
* The last step is repeated for the seasonal solar energy sums and the derivation of best-fit curves.  
The significance of the results of the present study as far as the solar industry and society of Saudi Arabia are concerned can be summarised in the following. The solar engineering society now has a map with fresh knowledge about the solar potential for mode (iii) solar systems across Saudi Arabia. This knowledge may prove useful for designing such systems. On the other hand, actions from governmental policies may have indirect benefits to the society, if these policies promote renewable energy sources in  
\begin{table}
\begin{tabular}{l c} \hline
**Definition of Ratio** & **Increase (\%)** \\ \hline \(\rm H_{g,t/\rho_{g}}/H_{g,\beta,\prime/\rho_{g}}\) (mode (iii)/mode (ii)) \(\cdot\) 100 & 4.22 \\ \(\rm H_{g,t/\rho_{g}}/H_{g,\beta,\prime/\rho_{g}}\) (mode (iii)/mode (i)) \(\cdot\) 100 & 28.81 \\ \(\rm H_{g,t/\rho_{g}}/H_{g,0}\) (mode (iii)/horizontal) \(\cdot\) 100 & 37.00 \\ \(\rm H_{g,\beta,\prime/\rho_{g}}/H_{g,\beta,\prime/\rho_{g}}\) (mode (ii)/mode (i)) \(\cdot\) 100 & 23.60 \\ \(\rm H_{g,\beta,\prime/\rho_{g}}/H_{g,0}\) (mode (ii)/horizontal) \(\cdot\) 100 & 31.47 \\ \(\rm H_{g,\beta,\prime,\prime,\rho_{g}}/H_{g,0}\) (mode (i)/horizontal) \(\cdot\)100 & 6.36 \\ \hline \end{tabular}
\end{table}
Table 4: Increase (in %) in the annual solar energy sums from all 82 sites in Saudi Arabia when using horizontal, mode (i) static, and modes (ii) and (iii) dynamic configurations.  
Saudi Arabia (and especially solar energy sources), because of the new knowledge gained through the present work.