Multi-unit EV charging hits roadblock
New tariffs needed for EV adoption in condominiums
By Robert Borkowski
Member, Electric Vehicle Association of Greater Washington D.C., and President, Clarksburg Condominium II
The rapid growth of electric vehicle (EV) adoption—and the resulting need for more charging stations in multi-unit dwellings (MUDs)—has brought about the need for new utility tariffs to mitigate the high and unpredictable cost of electricity to feed those stations, as well as problems arising from an outdated tariff structure.
Most MUDs would want to install 6 or more Level-2 EV supply equipment (EVSE) chargers to serve the needs of their tenants. To service this number of EVSEs, the MUD must have dedicated commercial electric service, and this involves pricing that can result in much higher costs due to tariffs on peak demand charges.
The traditional commercial tariffs make the cost of electricity not only more expensive, but also very unpredictable, especially during early transition when EVSEs are utilized at 25% or less. Commercial electric services use Demand Charges, calculated with complicated and sophisticated formulas used to come up with a “financial fine” when a site creates large demand spikes for power kW but at the same time does not draw a large amount of energy kWh during a billing cycle. The Demand Charges are independent of the Time of Use, thus a site is equally penalized when its Demand Charge is registered at midnight, when demand is low, and in the afternoon, when demand is high.
The result? Six EVSEs at an MUD in Maryland, each capable of dispensing 8.3kW, can be subject to energy costs ranging from $0.30 to $0.43 per kWh, while the typical cost of electricity on a residential rate in Maryland is about $0.12 per kWh. Therefore, residents living in MUDs are financially penalized compared to residents charging EVs at single-family dwellings.
This issue affects not only MUD properties but also other public Level-2 EVSEs installed in Maryland and throughout the nation.
What happened at Clarksburg…
In March of 2022, our forward-thinking community in Clarksburg, Maryland, installed 6 Level-2 Commercial EVSEs. Despite the relatively low demand for EV charging at the time, the association intended to be prepared for the expected rise in EV charging demand. The board members even made certain that the EVSE site, on a new dedicated 400 amp 3-phase commercial service, would allow it to expand and add up to 11 Level-2 plugs when future demand warranted, ultimately supporting 17 EVSEs dispensing electricity at a maximum rate of 8.3kW or 30 miles per hour of range for each EV.
During the first 9 months in operation, the 6 EVSEs at Clarksburg were utilized at 3%.
Clarksburg Condominium II has two charging rates, registered condo residents paying $0.20/kWh and guests (public) paying $0.35/kWh. Because of the unpredictable cost of electricity, the association accumulated $1,600 in losses during the first 7 months of operation. To decrease the rate of financial losses, the condo aggressively limited the max power (software limited max Demand Charge) that the bank of EVSEs can dispense from 50kW down to 9kW.
This temporary solution to control the cost of electricity has had a significant and negative impact on the rate and speed of charging. With no limits, each EVSE can deliver 8.3kW and each EV could charge at approximately 33 miles per hour. To add 100 miles of range, it would take 3 hours. Limiting the max power to 9kW shared by all six EVSEs has had the following impact:
Charging 2 EVs simultaneously at 4.5 kW equates to 18 mi/hr and requires 6 hrs to add 100 miles of range.
Charging 3 EVs simultaneously at 3.0 kW equates to 12 mi/hr and requires 9 hrs to add 100 miles of range.
Charging 4 EVs simultaneously at 2.3 kW equates to 9 mi/hr and requires 11 hrs to add 100 miles of range.
Charging 5 EVs simultaneously at 1.8 kW equates to 7 mi/hr and requires 13 hrs to add 100 miles of range.
Charging 6 EVs simultaneously at 1.5 kW equates to 6 mi/hr and requires 16 hrs to add 100 miles of range.
As a reference point, the cost of electricity is equivalent to the following gas prices:
$0.20/kWh = $1.62 per gallon
$0.35/kWh = $2.83 per gallon
$0.43/kWh = $3.50 per gallon
A preferred long-term solution
Utilities must implement solutions to mitigate the issue of high electricity costs for EV charging at MUD properties. The MUDs are residential, but the tariffs that the utilities offer are more in line with those charged for industrial customers.
A pilot program has been proposed by some utilities in Maryland to create a dedicated tariff with a higher Demand Charge limit of 150kW, raising it from the current 7.5kW threshold. While this is a good start, it is important for the program to include all current and future public EVSE sites (Level-2 and Level-3) in order to be truly effective. The proposed pilot should include MUD installations and create a path to become a final solution with this dedicated tariff.
Incentivizing Level 2 charging
It is important to consider and preserve the integrity of the electric grid. A typical 150kW Direct Current Fast Charger (DCFC) that is charging one EV is equivalent to simultaneously charging 20 EVs on Level-2 EVSEs. Given the option to have 20 DCFCs running at 9 MW for 10 minutes or 20 Level-2 EVSEs running at 150kW for 3 hours, utilities will strive to preserve the grid with 20 EVs charging on Level-2.
Conclusion
Dedicated tariffs for EVSE are the best solution to promote Level 2 charging. The EVSE tariffs should be either at fixed cost per kWh, similar to the residential tariff, or should go toward an alternative solution of a tariff with higher demand charge limit EVSEs at MUDs. By raising the limit from 7.5kW up to 150kW or higher, EV owners at MUDs would no longer be financially penalized when compared to EV owners at single-family dwellings on a residential electric meter tariff.
Further Reading:
Demand Charges are a component of a tariff. The following two whitepapers discuss tariffs for EV Charging:
The following is an example from the solar power world: