In 2023, Portland General Electric (PGE) launched the Residential EV Smart Charging Pilot, one of the country’s first managed charging offerings to include a control group of EV drivers who received incentives to participate without having their EV charging managed. The randomly assigned control group provides a valid baseline to quantify pilot impacts and provides insight into unmanaged charging patterns. PGE and their implementation partners managed EV charging every weekday and non-holiday. They tested several interventions, including technology type (Electric vehicle supply equipment [EVSE] hardware vs. telematics), time-of-use rates vs. direct load control, time of day when events are called, length of the event, and event season. At the end of 2024, 6,150 customers had participated in the Pilot across six event seasons. PGE hired Opinion Dynamics to complete an impact evaluation of the Pilot, which included a load impact analysis to estimate the impact of the pilot on shifting EV charging load and explore the drivers of event performance and a process evaluation, which included a survey of Smart Charging Customers to understand the customer experience with the Pilot.

KEY INSIGHTS

• Passive and active charging load control were both effective at shifting charging load away from PGE’s peak period, though active managed charging achieved greater absolute and relative load reduction than passive load control through a time-of-day (TOD) rate. The figure below shows the average load curves for customers in the control group who were on a fixed rate, control group customers who were on the TOD rate (i.e., passive), and treatment customers on a fixed rate (i.e., active). Active managed charging achieved an average load reduction of 70% during the 5:00 p.m. to 8:00 p.m. treatment period, while passive achieved a 40% reduction.

• The absolute level of charging load reduction during event periods is driven by the amount of baseline load available to shift. Participants were assigned to one of two different treatment windows: an early evening event period from 5:00 p.m. to 8:00 p.m. and a late evening period from 10:00 p.m. to 12:00 a.m.

• • The unmanaged control group showed that the baseline charging load during the early evening window was 54% lower than the late evening window. The relative load reduction was the same for the two event windows.

• Our results show that it is possible to combine passive and active load control successfully. Participants on a TOU rate were assigned to the late-night event period so their period of active load control would not overlap with PGE’s peak rate period. Most TOU customers did not charge during the peak window and then allowed their charging to be curtailed during the event window that followed. The majority of charging took place overnight during early morning hours.

• We observed growth in the amount of curtailable charging load and seasonal variation in the percent load reduction relative to baseline load across the three event seasons. As EV ownership increases and new vehicle models arrive on the market, EV owners’ driving patterns and charging needs will likely change. It will be important for utilities to continue to monitor baseline charging patterns over time to support distribution system planning.

WHY IT MATTERS

• PGE used an industry-leading experimental design for the Smart Charging Pilot that allowed us to conduct one of the most rigorous evaluations of managed charging program impacts to date.

• The sophisticated pilot design offered a unique opportunity to understand customer charging behavior, associated load impacts, and the pilot design factors that drive performance.

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