Electric vehicle drivers have been hit with peak-time price rises at thousands of roadside charging points.
Major networks including Ubitricity, the UK’s largest public charge-point operator, and Geniepoint have introduced “dynamic pricing” where users pay extra if they charge at times of day when electricity demand is high.
A quarter of public charge-points, excluding rapid and ultra-rapid devices, are now covered by this pricing model, according to the market analyst Cornwall Insight – although this is concentrated in London.
More than a fifth of the rapid and ultra-rapid network is also covered by peak and off-peak rates. Tesla and Char.gy, owned by Zouk, also use dynamic pricing.
Drivers are charged a higher or lower rate depending on when they top up, to reflect wholesale and network costs which increase when demand is high.
Ubitricity is currently charging drivers 45 pence per kilowatt-hour for 21 hours of the day, down from a previous 49 pence per kilowatt-hour, but 79 pence per kilowatt hour between 4pm and 7pm – a difference of 75pc.
The changes should allow drivers to take advantage of cheaper rates during the day and help lessen pressure on the grid.
However, it risks triggering concern that drivers who cannot avoid charging during peak periods are being penalised.
Experts warned prices need to be transparent and properly communicated, and avoid deterring drivers at a time when they are being encouraged to buy electric vehicles.
Oliver Archer, lead analyst at energy market experts Cornwall Insight, said: “Against the backdrop of rising commodity costs, charge point operators are trying to price in a way that supports the best use of their network, while still reflecting high input costs.
“The challenge lies in setting a tariff that works for charge-point operators and drivers.
“Using the public network can already be complex and frustrating, and charge-point operators need to ensure that dynamic pricing is seen as an opportunity by customers and not simply another inconvenience.”
James Court, chief executive of the consumer group EVA England, said: “If it means that we’re getting cheaper electricity outside of those [higher price] periods, then that’s a benefit.
“If it’s just a way of people jacking up prices midway through the day and you don’t see the benefit, obviously that’s not great.”
Wholesale electricity prices have soared this year because of high gas prices caused by Russia’s invasion of Ukraine, as well as lower nuclear output in France and the UK.
Prices are also becoming more volatile throughout the day as an increasing amount of electricity comes from intermittent wind and solar power.
Charging consumers at different rates depending on when they use electricity is set to become increasingly common, both at home and on public electric car charge points.
Changes were made to regulations last year to enable greater use of so-called “time-of-use” tariffs at home.
It means households can get cheaper electricity if they can be flexible about when they use it – but campaigners warned that households who cannot be flexible need to be protected.
GeniePoint, which has more than 900 chargers, introduced its GenieFlex tariff on November 18. Drivers will continue to pay 57p per kilowatt-hour after 8pm until 8am, but 75p per kilowatt hour the rest of the time.
GeniePoint said: “We launched GenieFlex on November 18 2022 with the ultimate goal of providing customers with access to lower rates at times when charge points are less likely to be in use, as well as supporting UK grid capacity.”
Ubitricity, which is owned by the FTSE 100 oil and gas giant Shell, said: “Between 4-7pm the price we pay to supply our charge points with electricity more than doubles due to peak demand on the national grid.
“Rather than distribute this increased cost throughout our standard pricing, we’ve decided to limit this price increase to a peak window. This helps ensure we can offer the best value reduced rate to our customers for the majority of the day.”
It said that 77pc of its customers’ charging is done outside of the peak window.