# Review of Renewable Energy-Based Charging Infrastructure for Electric Vehicles
## 9 Challenges of Renewable Energy-Based Charging Infrastructure  
**Power quality:** It was noticed that generating renewable power could introduce power quality problems. According to the changing nature of wind and solar, generating renewable power is intermittent, with high fluctuations, and non-dispatchable [120]. The RCI features mainly in charge of power quality challenges include the modularity of renewable generators. Power quality seems to be one of the most critical aspects that could affect the reliability and stability of RCI.  
**Stability:** It refers to the recovery of the power system after blackouts and control of the voltage and frequency. Stability challenges are mostly caused by the excess of power from renewable energy, and battery storage that can cause significant damage to RCI [121]. Controlling the stability can ensure the power system is performing correctly and not approaching instability.  
**Power balance:** The power unbalancing occurs in RCI because of the renewable sources' uncertainty and variability. This challenge relates to the long-term balance of active supply and load in the power system. This includes the system-wide coordination of ramp rate capacities and minimum generation levels of a power system [122].  
**Charging prices:** The vast implementation of renewables alters the structure of costing to be capital intensive. To ensure that implementation is profitable, the pertinent planning firms need to consider long-term energy prices [123]. Notably, the number of utility programs that offer renewable energy-based EV charging is limited and only concerned about residential customers. There is a need for various approaches to serve heavy-duty vehicles, employee workplace charging, and retail customers at the public charging loads.  
**Locations:** The literature demonstrates several attempts to evaluate medium- and large-scale wind farms to secure energy demand required by the EV charging infrastructure. It was noticed that urban areas are not suitable for installing the turbines as the wind energy-based system requires broad premises. The large buildings are the major obstacles in wind  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Approach** & **Advantages** & **Programs/Plans** & **Example of Costing** & **Utility** \\ \hline \multirow{3}{*}{Renewables’ network charging} & –Enables customers to charge with renewable sources. & –Pay per use. & 2 USD per h & \multirow{3}{*}{Austin Energy} \\  & –Encourages drivers to charge at beneficial times & 4.17 USD per month & & \\  & –Encourages charging at & –Changing with renewable energy. & & \\  & –Encourages charging at & –Changing with renewable energy. & & Great River \\  & – & –Merge TOU rates with renewables’ & & Energy \& \\  & and avoiding peak hours & pricing program & & \\  & – & Beneficial & & \\  & –Free management and control charging & –Free employee & & \\  & – & charging & & \\  & –Allows utilities to control charging remotely to meet grid needs. & –Managed charging program & & \\  & –Shifts charging loads to times when there is excess renewable energy generation on the grid & –Time of use & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Renewables’ charging programs.  
directions. However, some city authorities do not allow heavy-duty vehicles to enter cities at specific times. Thus, installing charging infrastructure in suburban or rural areas can serve medium- and heavy-duty vehicles.  
By contrast, the installation of RCI in urban areas could face some problems. For instance, in multi-unit residential buildings, the study [59] stated several problems: parking availability, building limitations, and governance issues. Hence, optimal planning of location and optimal scheduling for charging are critical factors that must be considered in implementing RCIs.