# 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
#### 5.2.5 Scenario 2e  
The hypotheses for scenario 2e are shown in Table 7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**EV\#** & **Arrival Time** & **SOC at Arrival** & \
\begin{tabular}{c} **Desired SOC at** \\ **Departure** \\ \end{tabular} &
\begin{tabular}{c} **Charging** \\ **Mode/Power** \\ \end{tabular} \\ \hline EV1 & 09:40 & 64\% & 75\% & Slow/1.8 kW \\ EV2 & 10:00 & 58\% & 100\% & Fast/22 kW \\ EV3 & 10:50 & 57\% & 63\% & Slow/1.8 kW \\ EV4 & 14:40 & 60\% & 66\% & Slow/1.8 kW \\ EV5 & 15:00 & 75\% & 64\% & Fast/22 kW \\ \hline \hline \end{tabular}
\end{table}
Table 7: Hypotheses for Scenario 2e.  
Figure 21: (**a**) EVs charging power and EVs SOC evolution for Scenario 2c; (**b**) EVs charging power and EVs SOC evolution for Scenario 2d.  
Figure 22: (**a**) Energy system distribution; (**b**) EVs energy distribution for Scenarios 2c and 2d.  
The total EVs demand energy is 36 kWh. Figure 23 shows the system power flows and the stationary storage SOC evolution.  
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 10:00-10:50 and 15:00-15:10. At 10:50, the stationary storage has reached its capacity limit, SOC of 20%, so the public grid supplies more power to the EVs since PV production is insufficient. 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 has reached the power limit, around 12:50 and 13:10.  
The EVs charging power and EVs SOC evolution for scenarios 2e is shown in Figure 24.  
Figure 25 shows a comparison between the two scenarios. The difference in scenario 2e with scenario 2c is that EV2 wanted to charge 42% of its battery capacity in fast mode. Therefore, EV2 is charged mainly with the public grid and a small portion with PV. Moreover, EV2 will affect negatively EV1 and EV3 and, therefore, the PV benefits for EV1 and EV3 have reduced since EV2 charges in fast mode for around 1 h and the three EVs charge simultaneously for a while.  
Figure 23: Scenario 2e, system power flows and stationary storage SOC evolution.  
Figure 24: EVs charging power and EVs SOC evolution for Scenario 2e.  
In conclusion, scenario 2e shows how fast charging mode affects negatively the other EVs currently in charge and their dependency 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. In contrast to scenario 2d, in scenario 2e, EV2 charges with 22 kW, and the requested SOC at departure is 100%. Therefore, the percentage of stationary storage energy remains low. So, the main issue for PV-powered EV charging stations, is how to increase PV penetration for EVs charging? In what conditions? What is the appropriate sizing of the system?