## 2 Materials and Methods
### PV System Design  
#### 2.3.1 Shading Analysis  
For an accurate PV system design, the proposed system is simulated using PVSYST [17]. Simulation results are only as accurate as the input data. Data related to solar radiation in Amman, including horizontal global irradiation, diffused irradiation, ambient temperature, and global incident radiation, were obtained from the Meteorom database [18].  
Due to the route being within city limits, mostly in business districts, the crucial input data is the shading information. Shading data wrtr obtained by actual readings using SunEye equipment. This enabled capturing the losses due to shading and high rising objects along the zones.  
As the routes cross many different areas with different topography and buildings distribution, shading at each point on the route is not like any other points. This is the main reason for using the zoning system and calculating the shading for each zone as an average. The routes are divided into fifteen zones, as shown in Figure 2. The start and end of every zone were determined based on  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Electric Energy Consumer** & **Energy Per Year** \\ \hline Electric Buses & 17,313,480 kWh/year \\ Street Lighting & 800,230 kWh/year \\ Stations and Service Buildings & 10,908,570 kWh/year \\ Total Energy Demand & 29,022,280 kWh/year \\ Transformers Losses & 1\% \\ Cables Losses & 1\% \\ Additional Capacity to Cover Yield Losses & 8\% \\ Design Grand Total & 32,000,000 kWh/year \\ \hline \hline \end{tabular}
\end{table}
Table 1: Transportation network energy demand.  
direction and length. This determines the studying each zone as a separate project for designing the PV systems.  
According to this configuration, line 1 has zones 1 through 11, while line 2 includes zones 12 through 15. Some parts of the corridors were eliminated because of inconvenient conditions, such as intersections, bridges, tunnels, and many existing high buildings.  
For each zone along the routes, several points were selected for data measurement, one point representing the worst possible shading in that zone where high buildings or obstacles exist. Another point represents the lowest possible shading in that zone. The remaining points cover the normal or average shading in the zone. The average shading for all points will be considered as the shading factor of this zone. Selection of highest and lowest shading points took place based on actual site visits.  
Zone 2 was chosen to validate this approach, as it has the highest shading due to many existing commercial buildings in that zone. The shading analysis first started using 5 points (highest shade, lowest shade and 3 average points). Then, a new session for shading analysis started using 19 points; the difference in overall average annual solar access was 2%. This percentage is acceptable, especially knowing that zone 2 has the highest shading in comparison with the other zones, which means this difference will be lower over other zones. Figure 3 shows the location of data sampling in Zone 2.  
Figure 3: Location of data samples in zone 2.  
Figure 2: Zones of Amman BRT route.  
Readings for shading and solar access were at 1.5-1.7 m elevation. This formulates an extra indirect safety factor, since the installation of PV panels will be much higher than this elevation. Thus, PV panels' access to solar radiation will be higher than what is used in the calculations. Therefore, results and outcomes of this study regarding electric generation from photovoltaic system will include a safety factor that affirms, in reality, the ability to produce more electricity than proposed.