Fort Missoula, Full Moon

Managed Electric Vehicle Charging

Posted: April 1, 2022
Dan Rogers
MEC Energy Specialist

With rising gas prices, many are taking another look at electric vehicles (EVs) as an option. Some of the top automotive manufacturers have already announced an end to production for gas and diesel engines in the near future. A quick check of online auto retailers like Vroom and Carvana shows a significant reduction in inventory of used EVs. As drivers seek out ways to insulate themselves from high gas prices, utilities are already preparing for the coming transition to an electrified future of motoring.
While EVs offer many positives for owners, including reduced fuel and maintenance costs, widespread adoption of the technology could pose a challenge to power providers and the grid as a whole. Electricity is so integral to our daily lives that we often take for granted how much must take place to ensure that the lights go on the second you flip the switch. Power systems are designed and built to accommodate future load growth based on observed trends. The loads that power providers are most concerned with are peak loads when everyone is using a large amount of power.

With these new loads rolling onto utility lines, the key to success will be in their management. This management means moving the loads to off-peak hours, when ample capacity exists. At MEC, we have what is called a diurnal peak, meaning we have one peak in the morning and one in the evening. Plugging in thousands of EVs during peak hours could rob capacity from other things we need to do in our households like cooking, heating water or doing laundry. Fortunately, there are plenty of hours overnight when this charging can take place and provide a full battery by the time EV owners leave for work.

In preparation for this transition, MEC will launch a managed charging pilot program. The pilot will be limited initially to 100 participants. The program is our smart level 2 residential charger, which provides twice the amount of range when compared with the chargers typically provided by the manufacturer.

These “smart” chargers give the Cooperative the ability to create time periods when charging can take place without adding to the system peak. In addition, the chargers contain revenue-grade metering so the Cooperative can isolate the energy used by the charger from the rest of the home. Metering the usage separately allows for the opportunity to charge a separate, lower rate for this usage since it will occur when electricity is at its lowest cost.

Managed charging can also help members manage their own peaks. Consider that a typical residential service is tied to a 15 KVA transformer. This size transformer can comfortably feed a load of around 15,000 Watts or 15KW. Level 2 EV chargers start at 7.7KW, meaning half the capacity of this size transformer will be consumed by charging. Depending on what other electric loads you have in your home, charging an EV during peak hours could mean bumping up on the limits of your home’s service. Charging during off-peak hours, on the other hand, avoids competing with other loads in your home while still receiving enough charge for your driving needs.