Leveraging EV Flexibility: Steering Customer Charging Behavior for the 21st Century Grid
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- Mar 30, 2020 8:01 pm GMT
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As more electric vehicles (EVs) hit the road across the US and require charging, utilities and grid operators will be faced with a growing challenge – how to most effectively manage the addition of millions of large, connected, temporally- and spatially-dynamic loads to their systems. Most estimates measure the additional energy load potential from EV charging in terawatt-hours – billions of kilowatt-hours – and suggest that aggregate new EV charging load by 2030 could represent between 1.5% and 8.6% [ 1 ] of the US’s current total electric energy consumption, which currently stands at about 3,900 TWh per year [ 2 ] . On the demand side, estimates of load impacts from EV charging are similarly staggering, with one study estimating that unmanaged EV charging will add nearly 5 GW to California’s peak demand by 2030 [ 3 ] , to say nothing of similar peak demand impacts in other states.
In recognition of the challenge and opportunity posed by this new EV charging load, utilities around the country have begun piloting managed charging programs to shift charging load away from peak hours. As of May 2019, 38 US utilities were conducting managed charging pilot or demonstration projects. Additionally, over half of the surveyed utilities expressed interest in managed charging technology and approaches that can reduce peak demand, help their customers manage their energy use, and increase customer engagement [ 4 ]. With the number of available EV models increasing and forecasts suggesting EVs will soon achieve cost parity with their internal combustion counterparts, there is enormous value for utilities to proactively identify and test the effectiveness of low-cost managed charging strategies so that they can seamlessly integrate new EV load into their networks in the coming years.
The term “managed charging” – also referred to as “smart charging” or “V1G” (the uni-directional sibling of “vehicle-to-grid,” or V2G) – encompasses a wide array of solutions that allow utilities to control the time, magnitude, and location of EV charging to provide grid services and ensure grid reliability. The solutions currently being piloted tend to focus on reducing on-peak charging either via incentive-driven behavioral methods or direct load control (DLC). Behavioral approaches typically mimic EV-specific time-of-use (TOU), providing per-kWh rebates for charging that occurs off-peak; other versions of this approach offer a fixed monthly (or quarterly) reward for avoiding on-peak charging altogether, with the potential loss of some or all of the reward for charging on-peak during the period. DLC approaches, on the other hand, typically focus on throttling EV charging rates during peak periods or on especially hot days, either through a signal sent to the vehicle itself or to a networked charger. Measurement and verification (M&V) of charging activity is critical to evaluate the effectiveness of managed charging programs and to determine which approaches deliver the most cost-effective and persistent load-shifting. Data for M&V can come from multiple sources, including vehicle telematics, devices that interface with a vehicle's on-board diagnostics port, networked chargers, or even through load disaggregation analysis of advanced metering infrastructure (AMI) data.
In addition to the potential program designs discussed above, there are many more exciting managed charging opportunities that have yet to see wide adoption and testing, including:
- Tiered off-peak programs that spread charging over a multi-hour window, minimizing timer peaks
- Gamification approaches that can shift load via non-monetary incentives
- Dynamic workplace load management programs that shift charging to periods of high solar generation
- “Upstream” approaches, in which a utility pre-sets the charging schedule on an EV owner’s networked home charger in partnership with the equipment manufacturer or installer; this approach minimizes the burden to the EV owner while potentially resulting in more persistent load shifts
The benefits of managed charging also go beyond supporting increased EV adoption and helping to ensure grid reliability. By forging a mutually beneficial connection between the utility and the customer, managed charging programs can create a valuable engagement pathway with customers, which could spur greater participation in other utility efficiency and demand-side management programs, increase residential and workplace load flexibility, and bolster the use of renewables. A customer who has a pleasant experience participating in their utility’s home managed charging program, and perhaps saves some money in the process, will likely be more willing to enroll in their utility’s other programs, including whole-house TOU rates or smart device load management programs for thermostats, water heaters, pool pumps, and more.
Now is the time for utilities to test, understand, and demonstrate the effectiveness of various managed charging solutions in shifting charging loads from on-peak to off-peak hours. As more and more drivers switch to EVs, managed charging will become a critical tool for reducing the coincidence of on-peak charging and better aligning EV charging with periods of high or excess renewable power generation. Ultimately, the utility of the future needs managed charging programs that are well designed to support increased electric sales, greater customer engagement, and reduced greenhouse gas emissions – without adding to existing grid peaks or threatening grid reliability.
[ 1 ] Multiple authors, Preparing for an Electric Vehicle Future: How Utilities Can Succeed, Smart Electric Power Alliance (2019), 10, https://sepapower.org/preparing-for-an-electric-vehicle-future-highlights/ (values calculated)
[ 3 ] Zoheb Davar, "The Path to a Vehicle-to-Grid Future," https://sepapower.org/knowledge/the-path-to-a-vehicle-to-grid-future/
[ 4 ] E. H. Myers, A comprehensive guide to electric vehicle managed charging, Smart Electric Power Alliance (2019), 16, https://sepapower.org/resource/a-comprehensive-guide-to-electric-vehicle-managed-charging/