Looming changes to network fees will significantly reduce the value of domestic vehicle-to-grid (V2G) charging, according to the findings from a government-sponsored trial.
Analysis of the results suggested that V2G charging could allow drivers to save or earn £340 annually – compared to £120 per year for smart charging alone – but planned changes to network fees could see this amount chopped in half.
Project Scirius – the world’s largest V2G trial to date – was partly funded by the Office for Low Emissions Vehicles and the Department for Business, Energy and Industrial Strategy in partnership with Innovate UK. It involved a number of partners, including energy supplier Ovo Energy and its energy tech subsidiary Kaluza, the carmaker Nissan, charger manufacturer Indra and the consultancy Cenex.
The trial initially sought to install and trial 1,000 of Indra’s 6kW V2G chargers in the homes of Nissan Leaf drivers over a period of two years. However, a lack of suitable participants and a delay in the certification of the chargers meant this target was reduced to 300 to 400 and the duration extended to three years.
The findings from the trial are primarily derived from data collected from just over 300 chargers between January and December of 2020, although only a fraction of them over the full 12 months. More than 100 units had been installed by the beginning of the year. The connected vehicles had a range of battery sizes between 24kWh and 62kWh.
Participants were offered a fixed export tariff of 30p/kWh for V2G charging, which was aggregated, optimised and scheduled using Kulaza’s smart energy platform.
This data was used by Cenex to model how much they could earn when provided with half-hourly import and export tariffs incorporating wholesale electricity prices on the spot market, transmission and distribution network charges and policy levies in the case of the import tariffs, as well as compensation for grid services such as Firm Frequency Response and Dynamic Containment.
It found that on average drivers could expect to save or earn £340 annually – compared to £120 per year for smart charging alone – with the figure rising to £513 when also providing Firm Frequency Response (FFR) or £725 when also providing Dynamic Containment (DC).
Revenue by battery capacity
Cenex said the coronavirus lockdown is thought to have a led to an increase in plug-in availability – 70 per cent in 2020 compared to 57 per cent in 2019 – but said both figures represent a significant behaviour change when compared to the typical availability without V2G charging of 30 to 40 per cent.
A survey of almost half of the participants found nearly three quarters thought it was important that their next electric vehicle had vehicle-to-charging capability.
Greg Payne, senior technical specialist at Cenex, said: “This hugely ambitious project combined experts in energy, transport, and infrastructure to develop a real-world domestic solution for V2G and install hundreds of units in people’s homes across the UK.
“The participants in the trial have really embraced the technology which shows just how far it has come in the last few years.”
Conor Maher-McWilliams, head of flexibility at Kaluza, said: “Balancing electricity supply and demand is becoming increasingly challenging as we ramp up generation from intermittent renewables and electrify transport. V2G is a compelling example of how intelligent electric car charging can create significant financial rewards for customers, while enhancing the resilience of the grid as we transition to net zero.
“The trial has provided some of the earliest insights into how the technology works in the real world and what is needed for it to be rolled out at scale. The V2G opportunity is a hugely exciting one which we are actively exploring here in the UK and internationally.”
However, Cenex noted several points of concern, including expected changes to Transmission Network Use of System (TNUoS) charges. Residual demand charges are currently based on consumption during the triad periods – the three half-hour periods of greatest demand each winter – but as a result of its Targeted Charging Review (TCR), Ofgem plans to replace these with banded fixed fees from April 2023.
When combined with the introduction in April 2021 of new Distribution Use of System (DUoS) export rates for domestic properties that are shaped rather than flat, Cenex said this will have the effect of reducing peak import prices and increasing export peak prices. It said this would cut the expected annual revenues from V2G charging (without grid services) by almost a half to £173, with the DUoS changes slightly offsetting the reduction due to the TCR. The expected value of smart charging alone would also fall to £83.
Average import and export tariffs before and after TCR changes
Cenex additionally highlighted the high cost of the V2G chargers, which by the end of the trial exceeded the cost of the equivalent smart chargers by around £3,700. At this price, the consultancy said the payback period for V2G charging (without grid services) would exceed 30 years. It said bringing down the additional hardware cost to £1,000 would shorten this period to nine years, whilst also stopping the changes to transmission network charges would cut it to five years.
