# PV-Powered Electric Vehicle Charging Stations: Preliminary Requirements and Feasibility Conditions
## 5 PV-Powered EV Charging Station Simulation Results and Analyses
### Case 2--Publicly Accessible Charging Station: PV Parking Shade with Nine Spots and Nine Chargers
#### 5.2.4 Scenario 2d  
The hypotheses for the scenario 2d are shown in Table 6.  
The total EV's energy demand is 18.50 kWh. Figure 20 shows the system power flows and the stationary storage SOC evolution. The stationary storage is charged only by PV energy, therefore, its power must be limited to not exceed the slow charging power of 7 kW.  
PV and stationary storage share power to charge the EVs in slow mode. However, when an EV comes to charge in fast mode and the stationary storage has reached the power limit of 7 kW, the grid supplies the EVs, at 10:00-10:10 and 15:00-15:10. When the PV production is higher than the EV's power demand, PV charges the stationary storage so it can supply further power afterward. Moreover, PV injects power into the grid when stationary storage reaches its capacity limit, SOC of 80% around 14:10-15:00, and when stationary storage reaches the power limit, around 13:10.  
The EVs charging power and EVs SOC evolution for the two scenarios 2c and 2d are shown in Figure 21.  
Figure 22 shows a comparison between the two scenarios. All EVs in slow mode are charged mainly with PV energy, except for EV4, where it comes in the late afternoon and the PV production is low. Whereas, EV2 and EV5 in fast mode are charged mainly with the public grid and a small portion with PV. Moreover, EV2 and EV5, since they charge in fast mode, will affect negatively EV1 and EV4 respectively.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**EV\#** & **Arrival Time** & \begin{tabular}{c} **SOC at** \\ **Arrival** \\ \end{tabular} & \begin{tabular}{c} **Desired SOC at** \\ **Departure** \\ \end{tabular} & \
\begin{tabular}{c} **Departure** \\ **Time** \\ \end{tabular} &
\begin{tabular}{c} **Charging** \\ **Mode/Power** \\ \end{tabular} \\ \hline EV1 & 09:40 & 64\% & 75\% & 13:00 & Slow/1.65 kW \\ EV2 & 10:00 & 58\% & 65\% & 10:25 & Fast/8.39 kW \\ EV3 & 10:50 & 57\% & 63\% & 11:50 & Slow/2.99 kW \\ EV4 & 14:40 & 60\% & 66\% & 16:40 & Slow/1.49 kW \\ EV5 & 15:00 & 75\% & 64\% & 15:20 & Fast/10.49 kW \\ \hline \hline \end{tabular}
\end{table}
Table 6: Hypotheses for Scenario 2d.  
Figure 20: Scenario 2d, system power flows and stationary storage SOC evolution.  
In conclusion, scenario 2d shows that EV2 and EV5 consume more PV energy than in scenario 2c and the public grid dependency has been reduced. This shows that the variable charging power based on time duration availability can improve the PV benefits and the EVs can depend more on PV and less on the public grid. The stationary storage could be emptied quickly, if its power is not limited, since for EVs charging in fast mode their charging power could reach up to 22 kW. Thus, in scenario 2c, EV2 and EV5 charge with a greater percentage of public grid energy. However, since the stationary storage is charged by PV sources only, as mentioned earlier, this could prove the superiority of scenario 2d over scenario 2c, as the PV energy and stationary storage energy combined are higher than scenario 2c, as shown in Figure 22d.