Strategic EV Charging to Ease Grid Strain
National and international climate strategies increasingly rely on two converging trends: the electrification of transportation and a greater share of electricity generated from renewable sources. Yet, projections indicate that these shifts could impose substantial strain on electrical grids, particularly during evening hours when electric vehicles (EVs) are typically plugged in after daily commutes. This surge in demand could necessitate costly new power plants. At the same time, midday overproduction from solar installations often goes unused due to limited storage capacity.
A recent study by MIT researchers Zachary Needell, Wei Wei, and Professor Jessika Trancik, published in *Cell Reports Physical Science*, offers a practical solution to both challenges without requiring complex, high-cost communication networks or advanced connected-device systems. Their approach centers on strategically locating EV charging stations and implementing delayed charging schedules.
The team analyzed detailed travel and location data from New York and Dallas, drawing on anonymized onboard vehicle records and targeted surveys. This dataset revealed patterns in vehicle usage, parking locations, and dwell times across residential, workplace, commercial, and entertainment areas. These insights, Trancik notes, “round out the picture on the question of where to strategically locate chargers to support EV adoption and also support the power grid.”
Workplace charging emerged as a key opportunity. By enabling employees to charge during midday, these stations could absorb surplus solar generation that might otherwise be wasted. This approach not only reduces the evening charging peak but also leverages renewable energy more effectively. The researchers estimate that unmanaged evening charging could drive the need for up to 20 percent more generation capacity, especially when combined with other peak loads such as air conditioning on hot days.
Wei emphasizes that “slow workplace charging can be more preferable than faster charging technologies for enabling a higher utilization of midday solar resources.” Slower rates extend charging duration, aligning better with solar output curves.
Delayed home charging offers another powerful tool. A simple, preprogrammed app could determine optimal start times so vehicles finish charging just before they are needed. This method avoids centralized control systems and relies instead on natural variability in individual driving patterns to smooth demand. Trancik stresses that “home charging” includes not only private garages but also curbside stations and apartment parking facilities.
Combining workplace charging with delayed home charging maximizes benefits. Earlier MIT work showed that home charging is especially effective for meeting drivers’ needs consistently, while workplace charging alone cannot fully substitute. “Given that there’s a lot of public money going into expanding charging infrastructure,” Trancik says, “how do you incentivize the location such that this is going to be efficiently and effectively integrated into the power grid without requiring a lot of additional capacity expansion?”
She adds, “I think one of the fascinating things about these findings is that by being strategic you can avoid a lot of physical infrastructure that you would otherwise need. Your electric vehicles can displace some of the need for stationary energy storage, and you can also avoid the need to expand the capacity of power plants, by thinking about the location of chargers as a tool for managing demands — where they occur and when they occur.”
The team found that even modest delays in home charging start times can significantly flatten demand peaks. “It’s basically incentivizing people to begin charging later. This can be something that is preprogrammed into your chargers. You incentivize people to delay the onset of charging by a bit, so that not everyone is charging at the same time, and that smooths out the peak,” Trancik explains.
Participation is critical. “You would need to have enough people committing to this program in advance to avoid the investment in physical infrastructure,” she says. If enough drivers opt in, additional generation capacity may be unnecessary.
However, timing matters. “If you want electric vehicles to act as an effective storage technology for solar energy, then the [EV] market needs to grow fast enough in order to be able to do that,” Trancik notes. She suggests competitive processes for installing workplace chargers to maximize public investment impact, while ensuring residential access to charging for convenience and travel continuity.
The research was supported by the European Regional Development Fund Operational Program for Competitiveness and Internationalization, the Lisbon Portugal Regional Operation Program, and the Portuguese Foundation for Science and Technology.
