A recent study found that electric vehicle (EV) batteries used as a utility virtual power plant (VPP) could shift the entire residential peak load to nighttime hours with only 10% EV market saturation.

The research was conducted by Jackson Associates, an Orlando, Florida-based firm that does energy forecasting, data development, and energy-related analysis. The study analyzed data on 5,000 individual Southern California Edison (SCE) utility customers including each customer’s hourly loads, commuting data, and battery reserves after afternoon commuting to simulate the ability of a VPP to clip the residential sector peak while constraining EV overnight recharging to avoid an overnight peak.

For the analysis, random weeks in January and August were reviewed to generate representative daily load shapes. The SCE EV time-of-use rate period differentials are applied to estimate cost savings.

Utility cost savings for each kWh shifted from on-peak to off-peak was approximated as the differential in those two rates. Shifting one kWh from the 4 p.m. to 9 p.m. on-peak time period to off-peak hours saved $0.25 in the summer and $0.23 in the winter. The report says weekend savings were not considered because weekday commuting savings are significantly greater than potential weekend savings, and because the data included actual commuting data for weekdays but not for weekends. Consequently, financial benefits should be considered lower-bound estimates.

“We were surprised at the relatively small 10% EV market saturation required to completely clip the SCE residential peak,” Dr. Jerry Jackson, president of Jackson Associates and author of the report, said in a press release. “These results suggest that utilities should shift from defensive ‘managed charging’ strategies to an offense strategy that draws on EV battery storage during peak hours with overnight recharging.”

Furthermore, the study found the scheme could save each EV-owning customer about $560 annually, after accounting for the cost of overnight recharging. The report says the results “highlight the urgency of developing appropriate utility programs, EV technologies and supportive regulations to take advantage of this new VPP resource.”

While these results suggest a significant potential for utility EV VPP programs, the report notes that the findings are specific to the SCE territory. Results in other areas could vary due to diversity in utility customer hourly loads, commuting behavior, avoided peak costs, cost of overnight charging, and possibly other factors. A more-detailed analysis would be required to assess individual service areas.

—Aaron Larson is POWER’s executive editor (@AaronL_Power, @POWERmagazine).