The United Kingdom plans to pass legislation that will see EV home and workplace chargers being switched off at peak times to avoid blackouts.

Announced by Transport Secretary Grant Shapps, the proposed law stipulates that electric car chargers installed at home or at the workplace may not function for up to nine hours a day to avoid overloading the national electricity grid.

As of May 30, 2022, new home and workplace chargers being installed must be “smart” chargers connected to the internet and able to employ pre-sets limiting their ability to function from 8 am to 11 am and 4 pm to 10 pm. However, users of home chargers will be able to override the pre-sets should they need to, although it’s not clear how often they will be able to do that.

In addition to the nine hours a day of downtime, authorities will be able to impose a “randomised delay” of 30 minutes on individual chargers in certain areas to prevent grid spikes at other times. 

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The UK government believes these measures will help avoid putting the electricity grid under stress at times of peak demand, potentially preventing blackouts. Public and rapid chargers on motorways and A-roads will be exempt, though.

The Department for Transport’s concerns are justified by the projection that 14 million electric cars will be on the road by 2030. When so many EVs will be plugged at home after owners will arrive from work between 5 pm and 7 pm, the grid will be placed under excessive strain.

The government argues that the new legislation could also help drivers of electric vehicles save money by pushing them to charge their EVs during off-peak night hours, when many energy providers offer “Economy 7” electricity rates that are far below the 17p ($0.23) per kWh average cost.

In the future, Vehicle-to-Grid (V2G) technology is also expected to mitigate strains on the grid in combination with V2G-compatible smart chargers. Bi-directional charging will enable EVs to fill gaps in power when demand is high and then draw power back when demand is extremely low.