## 3 Methods
### Estimation of the PV Potential from a Commuter's Solar EV According to the Operation Scenario  
Solar EVs can generate power (recharge batteries) while driving on the road or parked at rest stops or other places of interest. The most common example is when a commuter traveling to and from work utilizes a solar EV. Therefore, in this study, the potential of commuters to use solar EVs on sections of the Donghae expressway was estimated. The difference is that commuters can use solar charging when traveling between expressway sections or parked at a specific place during work.  
To evaluate the potential for commuting with solar EVs, four different scenarios were assumed for the commuter's residence and work location, commute time, driving section, working hours, and degree of shading (percentage) of the parking area, as presented in Table 3. In all scenarios, the commuter was assumed to arrive at work at 9 a.m., leave at 5 p.m., and drive at a speed of 60 km/h on a one-way section of the Donghae expressway to and from work. Scenarios 1 and 2 denote when a commuter goes to work from home (Sokcho) at 8 a.m., drives for 1 h on Sections A and B1 of the Donghae expressway, a distance of 60 km each way, parks the solar EV outside during the 8 h they work at their workplace (Gangneung), leaves work at 5 p.m., and drives for 1 h on Sections B1 and A back home. However, because the proportion of shaded areas may vary depending on the time of day when parking at work, this study assumes that no shadow is formed from 9 a.m. to 5 p.m. (Scenario 1) and that the proportion of shadows on the vehicle varies with time (Scenario 2). The reason for assuming that the percentage of shadows varies with time is that when driving on an expressway, the shadowed area can be determined by location through modeling; however, when parking near work, the driver can choose where to park. Conversely, for Scenarios 3 and 4, the distance between home (Yangyang) and work (Gangneung) is 30 km, and as the commuter drives on Section B1 of the Donghae expressway for 0.5 h, the time of arrival at work is 8:30 a.m. and the time of departure is 5:30 p.m. Other conditions, such as parking time and shading ratio at the workplace, were the same.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **Scenario 1** & **Scenario 2** & **Scenario 3** & **Scenario 4** \\ \hline House & Sokcho & Yangyang \\ \hline Workplace & Gangneung & Gangneung \\ \hline Driving section & Section A + Section B1 & Section B1 \\ \hline Driving distance (round trip) & 120 km (one way of 60 km) & 60 km (one way of 30 km) \\ \hline Driving hours & Go to work & 1 h (8 a.m. to 9 a.m.) & 0.5 h (8:30 a.m. to 9 a.m.) \\ \cline{2-3}  & Back home & 1 h (5 p.m. to 6 p.m.) & 0.5 h (5 p.m. to 5:30 p.m.) \\ \hline Shadowed region at expressway & \multicolumn{3}{c}{Identical condition in Figure 3} \\ \hline Parking hours & \multicolumn{3}{c}{8 h (9 a.m. to 5 p.m.)} \\ \hline  & 09:00 & 30\% & 30\% \\ \cline{2-3}  & 10:00 & 20\% & 20\% \\ \cline{2-3}  & 11:00 & 10\% & 10\% \\ \cline{2-3} Shadow ratio at & 12:00 & 0\% & 0\% \\ \cline{2-3} parking lot & 13:00 & 10\% & 10\% \\ \cline{2-3}  & 14:00 & 20\% & 20\% \\ \cline{2-3}  & 15:00 & 30\% & 30\% \\ \cline{2-3}  & 16:00 & 40\% & 40\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Commuter’s operational scenarios and assumptions for solar EV.