July 26, 2021
In India, charging stations are grid-tied and equipped with multi-standard chargers such as AC-001, DC-001, AC Type 2 AC EV Chargers, the CCS, and CHADEMO. Many times acquiring new land parcel in urban areas for establishing charging station become difficult. Furthermore, the existing grid capacity (transmission and distribution) needs to be upgraded to accommodate the extra load for charging. And EV car owners are vulnerable to grid-related problems and outages.
In this context, solar EV charging can be a boon for both car owners and the grid. The plummeting price of solar panels coupled with an increase in energy conversion from solar panels has paved the way for electricity generation from solar. And now, thanks to the development of embedded power electronics and the more efficient solar inverter has accelerated synergy between solar PV and EV.
Normally, charging an electric vehicle from a full day’s solar production in an unshaded area will require a PV system ranging from 2 kW - 14 kW. Depending on the irradiation potential of the specific location and types of solar panels, myriads solar panels can be installed in both stand-alone and integrated solar EV charging stations.
As battery charging can be done by solar panel, it relieves pressure on the existing grid and also set free car owners from the vagaries of grid-related problems. The solar rooftops meant for the home can be used to provide solar-based calibrated charging. Solar panels can be installed on parking places without disturbing existing parking facilities that obviates the need to acquire new land for erecting charging points at public places.
The Solar Inverter-Integrated EV charger provides rapid and efficient charging. It is 100% green electricity is produced from renewable while grid-tied charging station electricity is produced from fossil fuels. The life span of the solar panels is more than 20 years and 80% of solar panels can be recycled using advanced end-of-life recycling techniques.
Thanks to the photoelectric effect, a photovoltaic (PV) panel can convert the incoming solar radiation into electrical energy dc power. As the DC power produced by the panel is non-uniform and fluctuate with temperature during the day, MPPT (Maximum Power Point Tracking) is employed to convert the non-uniform, fluctuating dc power to uniform power for battery charging enabling solar PV to operate at the maximum (97%) efficiency. The output from MPPT feeds a common DC bus. The DC- AC inverter fed from the DC bus is used for slow charging applications such as two-wheelers and e- rickshaws, while the DC-DC converters fed from the DC bus are used for AC fast charging and DC fast charging.
In fast EV charging, a large array of electrically connected mobile solar panels are attached to moveable motor-controlled solar trackers. Based on the input received from the solar position algorithm regarding real-time maximum solar radiation, microcontrollers use the Pulse Width Modulation technique to control the bi-directional motor run tracker and align the angle of the solar panel to receive the maximum solar radiation.
In the case of excess charging demand, the bi-directional inverter receives electricity from the grid. And it feeds the DC bus while in the case of excess electricity production from solar panels, it exports power back to the grid with net metering. Depending on the type of vehicle connected and the demand raised by a battery monitoring system (BMS) of the vehicle, the central controller configures the DC-DC converter over the communication bus to ensure optimal charging. By continually monitoring supply and demand system controller decides how to fulfil the demand, whether from solar alone or a combination of solar and storage or partial input from the grid. The system has a full-proof protection mechanism to prevent malfunction triggered surges or lightning strikes, or short circuits, or over-temperature or over voltage-current conditions.
In the Indian context, southern western regions have higher insolation hence, solar-EV can provide 24X7 charging. But in areas where solar insolation is not sufficient, it is feasible to use integrated solar EV with backup from a grid or storage. Capitalizing on the huge solar potential, India has already taken a huge lead in the solar rooftop, solar floating, canal top, and solar pump segment. And now, India can also easily integrate its solar policy with EV policy.