## 5 Discussion  
### Comparison of the PV Potential of the Solar EV with Other Renewable Energy Sources  
The PV potential of solar EVs was compared with those of ground-mounted PVs and wind turbine systems to help in understanding the relative advantages and limitations of solar EVs. To make this comparison, it is necessary to calculate the amount of electricity that an entire fleet of vehicles traveling on the Donghae expressway could generate in a year, rather than a single vehicle's one-way trip. As such, the potential was also calculated when considering the traffic on the Donghae expressway instead of a single solar EV in this study. Hourly sectional traffic data for the Donghae expressway for 2021 were collected and compiled from the public data portal of the Korean Expressway Corporation [35] to reflect the average number of vehicles per hour for each section (Table 8). This is an estimate of the potential based on the assumption that the total number of vehicles traveling on the Donghae expressway, which is used by office workers, is the same as that of the solar-powered EVs used in this study. The average number of vehicles per day for each section ranged from 6265 to 7116 ea, and the potential was within the range of 208.2-861.9 kWh on the sunset day and 201.9-352.9 kWh on the moonrise day. The estimated potential of solar EVs was 1644.6 kWh on the summer solstice and 797.5 kWh on the winter solstice. The total potential of the summer solstice was approximately twice that of the winter solstice, and the potentials by section were B, A, and C in decreasing order. If it is assumed that the average potential on the summer and winter solstices is the potential for a single day, the total power generation (charging) of a solar EV traveling \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & \multirow{2}{*}{**Time**} & \multicolumn{3}{c}{**Number of Vehicles (ea)**} & \multicolumn{3}{c}{**PV Potential (kWh)**} \\ \cline{3-8}  & & **Section A** & **Section B** & **Section C** & **Section A** & **Section B** & **Section C** \\ \hline  & 07:00 & 225 & 327 & 347 & 5.9 & 5.9 & 2.8 \\  & 08:00 & 341 & 447 & 479 & 20.1 & 10.7 & 7.2 \\  & 09:00 & 501 & 516 & 444 & 43.1 & 24.8 & 7.5 \\  & 10:00 & 645 & 618 & 517 & 68.4 & 42.0 & 10.9 \\  & 11:00 & 790 & 753 & 553 & 81.4 & 90.4 & 24.9 \\ Summer & 12:00 & 744 & 747 & 574 & 56.5 & 127.7 & 43.1 \\ Solstice & 13:00 & 756 & 753 & 577 & 68.0 & 142.3 & 37.5 \\  & 14:00 & 737 & 772 & 593 & 80.3 & 139.0 & 30.2 \\  & 15:00 & 713 & 773 & 606 & 85.6 & 98.2 & 21.8 \\  & 16:00 & 659 & 756 & 597 & 34.9 & 90.7 & 13.1 \\  & 17:00 & 584 & 696 & 557 & 18.1 & 66.8 & 6.7 \\  & 18:00 & 421 & 520 & 421 & 12.2 & 23.4 & 2.5 \\ \cline{2-8}  & Sum & 7116 & 7678 & 6265 & 574.5 & 861.9 & 208.2 \\ \hline  & 09:00 & 501 & 516 & 444 & 6.0 & 7.7 & 5.8 \\  & 10:00 & 645 & 618 & 517 & 17.4 & 24.7 & 17.6 \\  & 11:00 & 790 & 753 & 553 & 27.7 & 47.4 & 29.3 \\  & 12:00 & 744 & 747 & 574 & 44.6 & 58.3 & 37.3 \\ Winter & 13:00 & 756 & 753 & 577 & 55.9 & 66.3 & 37.5 \\ Solstice & 14:00 & 737 & 772 & 593 & 47.9 & 63.3 & 34.4 \\  & 15:00 & 713 & 773 & 606 & 27.8 & 48.7 & 24.8 \\  & 16:00 & 659 & 756 & 597 & 12.5 & 29.5 & 10.7 \\  & 17:00 & 584 & 696 & 557 & 2.9 & 7.0 & 4.5 \\ \cline{2-8}  & Sum & 6129 & 6384 & 5018 & 242.8 & 352.9 & 201.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: PV potential on the summer solstice and winter solstice considering the mean number of vehicles per hour. on the Donghae expressway for a year (365 days) is approximately 445.7 MWh. This is compared with the power generation of a 341 kW land-based fixed PV power facility, considering that the average peak sun hours in Korea are approximately 3.58 h per day based on the recent literature survey [44]. Moreover, this is almost equivalent to the amount of power that a 217 kW wind turbine facility can generate taking into account the 23.5% yearly capacity factor of wind power facilities in Gangwon state [45].