As the automobile sector transitions from conventional to electric vehicles (EVs) globally, electricity distribution utilities (DISCOMs) become critical to facilitate EV charging. EV charging could also help increase DISCOM’s revenue from the additional electricity sales. Though it may lead to an increase in DISCOM’s revenues, it may also increase the peak load and impact the power procurement cost for DISCOM. This increase in power procurement cost could also impact other consumers of the DISCOM due to upsurge in cost of power. Thus, meeting the EV charging load may entail additional costs for the DISCOMs, which is reflected as a change in the cost of supply (CoS).

CoS is the easy proxy to study the electricity rate, as electricity regulators use it to set electricity rates in India. Therefore, to understand EV’s impact on electricity rate, the AEEE research team did a case study on Delhi.

To assess the impact of EV charging, DISCOMs of Delhi were selected as they are experiencing high growth of electric vehicles. It is assumed that each DISCOM has to support the charging of a mix of 10,100 EVs, where 100 are electric buses. The remaining vehicles were split between electric bikes (e-bike), electric rickshaws (e-rick) and electric cars (e-car). It is assumed that that the e-buses will only be charged at the bus depots. On the other hand, e-cars, e-ricks and e-bikes have multiple possibilities of charging. They can be charged at homes, captive locations, or public charging facilities. The results of the case study are summarised below:

• Because of EV charging, a marginal increase in energy requirement is predicted mainly in two-time slots, i.e. between 12-6 PM and 6 PM-12 AM. e-cars and e-buses primarily contribute to this.
• The peak demand from charging happens during the day. Public charging of e-cars would be the leading cause of day time demand.
• At night, charging of e-bikes will be at homes and a significant contributor to increased power demand. The relative increase in the electricity requirement due to EV charging is highest at night.
• E-bus charging can cause a sudden increase in the peak power demand at night, especially if all buses charge at the same time. Fast charging of buses has a higher impact on peak demand than slow charging.
• DISCOMs rarely need to plan for any additional increase in energy purchase at a moderate level of EV adoption.
• Only the DISCOM which had a maximum demand during mid-day and relatively lower energy share experiences the impact from EV charging load. In the other DISCOMs, the charging contribution is a marginal compared to total energy requirement.
• For most DISCOMs, EVs are good news as their CoS decreases marginally with EVs’ adoption initially and then starts increasing. This is because the DISCOMs are able to capitalise on the surplus capacity from the power purchase agreements.
• The study also evaluated how many EVs are required to cause a significant impact on the cost of supply. It was observed that the relative share of EVs that can cause an impact varies for each DISCOM. For the DISCOM which has the lowest share of energy, ~0.10 million EVs can cause an increase in the cost of supply. For DISCOMs with higher energy share, this ratio is 10x at to 1.13 million.

Overall, though Delhi case study results are promising, the results of this exercise could not be generalised and applied to other DISCOMs in India. There is a lot of variation among DISCOMs in India in terms of ownership, financial viability, consumer categorisation, tariff structure, etc. Further, the impact on every DISCOM will be distinct and will be contingent on multiple factors such as surplus power availability, level of EV adoption, EV mix and charging patterns, and the price at which the respective DISCOMs procure additional power. It makes sense to do DISCOM specific assessment to understand the possible impact of EV charging.

The blog is written by Bhawna Tyagi with inputs from Chandana Sasidharan and Nitin Kesar.