• EV tariffs
  • Aug 04, 2021

Charging an EV at home means we start to look at energy differently. EV tariffs give EV drivers low-cost charging at times when the grid was generally lower carbon too. Most EV tariffs have fixed cheap overnight windows to encourage drivers to plug in. The big difference for people looking to switch energy in 2022 are new choices, with the arrival of ‘managed’ or ‘intelligent’ charging, like the Ovo EV tariff, Drive + Anytime, or Octopus Energy’s Intelligent tariff.

What is a ‘time-of-use’ EV tariff?

EV tariffs reward us for using energy during the hours that are quietest on the grid. These hours are generally greener because there’s less need to switch on fossil-powered gas generation to meet demand. Greener energy costs less per kWh, so suppliers can offer a discount to make sure it was all used.

What’s different about an ‘intelligent’ or managed EV tariff?

A fixed off-peak window may avoid the busy peak, but it does not always coincide with the cheapest and greenest energy. Step in intelligent or managed charging. Managed charging allows a utility or third-party to remotely control your charging by turning it up, down – or even off – in line with the needs of the grid. It works within your schedule – it will still be ready when you need it, and you have the ability to ‘boost’ charging to override the programming. Electric cars connected like this support intermittent green energy sources and predictable short blips in demand.

How does managed charging work?

Your utility will connect either directly to your car (Tesla does this well) or, more likely, to your charging equipment through an app. You set the time you need your car to be ready, and the minimum charge you’ll need. Then, based on the supply of green energy, your car will charge when greenest for the grid across all the hours you’re plugged in.

Is managed charging better than a fixed EV tariff?

The popularity of the EV tariff Octopus Go, with an off-peak window of 12.30-04.30am, actually created its own mini-peak as thousands of EVs all automatically switched on to start their charging at exactly 12.30am. This kind of new night peak is far from ideal, and the whole point of off-peak charging is to shift demand outside of a peak and bring it into line with low congestion moments on the grid.

In response to this Octopus staggered the start times of its off-peak tariff with a new tariff called Go Faster. And as the number of EV tariffs increases, the off-peak windows will become more diverse.

Carbon cost of charging an EV

The carbon cost of charging an EV for the average mileage varies depending on how the electricity is generated

What’s the best tariff for me?

Compare EV tariffs

As well as moving more demand overnight, there is also value in controlling small demand ‘shimmies’. These may be seconds or minutes when there is pressure on the grid – like when we all switch our kettles on during half-time in an England football game. All that is needed is a short pause in your charging, to add to the demand response. This is the kind of flexibility that managed charging can provide.

The other answer to fixed-window EV tariffs is dynamic pricing, like Octopus Energy’s Agile tariff, that prices each half-hour of energy use according to predictions of supply and demand, as well as adding a ‘congestion charging‘ to the evening peak. Dynamic EV tariffs mean buying energy like we now buy air tickets – we expect to pay more on a popular date compared to a date when the plane is half empty. At times when we are all using the grid prices go up, and when there’s lots of energy, prices will fall.

How much does managed charging cost?

Ovo replaced their EV Everywhere tariff with the UK’s first managed charging tariff, Drive + Anytime this Autumn. This new EV tariff from Ovo means you’ll pay only 5p/kWh to power your car whenever you want. It’s currently the only “type of use” energy plan in the UK that offers EV owners a separate rate for their car and home. You can charge your car whatever time of day you wish, but the downside is you’ll keep paying your current rates for your home energy. It suits any household where routines are completely fluid and flexibility really is king.

New to the market around the same time, but as a trial or beta version, Intelligent Octopus gives users a low price night rate for their EV and home energy use of 5p/kWh between 11:30pm and 5:30am. Outside of these hours customers have a unit rate that varies by region and a daily standing charge, both are similar to the rates on the Go tariff.

Intelligent Octopus may end up scheduling your charging outside this off-peak window, but you’ll pay the same night rate. And if you need to charge more urgently, you can trigger a bump charge through the special app at your normal daytime rate.

How much could I save with a managed tariff?

Average prices among the top ten suppliers start from 16p per kWh. Prices vary between regions, with London being one of the cheapest regions. Assuming an EV uses 2,000 kWh per year charging at home (that equates to something like 8,000 miles), Ovo estimates that instead of paying £320 on a regular tariff, you’ll spend £120 on the Drive + Anytime preferential rate – a 63% saving on your charging.

Octopus, meanwhile, estimate a user who is already on an off-peak tariff will save a further £100 by switching to it’s intelligent tariff. This works out best for people driving higher mileages where the charging won’t always fit within the off-peak window. Their calculation assumes 15,000 miles driven per year with 100% of charging in the Intelligent Octopus window vs. 80% of charging in the Go window, and a day rate of 15.49p/kWh. This also includes savings in underlying household consumption for a longer night window.

What technology will I need for smart charging?

To be eligible to sign up for Ovo’s Drive + Anytime, you must install or already be using one of two Indra smart chargers:

  • Smart Charge (version 3)
  • Smart Pro

You also need to have either a SMETS2 meter, or SMETS1 meter made by a company called ‘Secure’. Your smart meter number is SMETS1 if it starts with 19P,  and SMETS2 if it starts with 19M.

Octopus Intelligent Octopus currently works with Tesla cars or Wallbox Pulsar Plus chargers. They are working to add more chargers. You’ll also need a smart meter. During early access, the app is only available for iPhones with iOS 14 or higher but an Android release is on the cards.

How much lower can my carbon footprint per mile go?

On average, each kWh of grid energy has just over 200g of carbon associated with it. That means, on average, 50g of carbon is produced somewhere else for every mile you drive in your EV.

The carbon behind your charging will in reality vary according to the supply from intermittent generation like wind turbines (or solar during the day) and the other demand on the system. The lowest grid carbon registered in 2020 was 42g, which reflects how the UK energy demand dried up during lockdown in May. As more renewables are built, the grid is getting cleaner. The target for 2030 is 100g per kWh.

Shifting from peak charging (coming home at 5pm and plugging in during the evening peak) to off-peak (automatically setting your charging from midnight onwards) lowers carbon intensity by 26% (we’ve used data on carbon intensity from National Grid ESO for August 2019 – August 2020). So just changing your charger settings means one tonne less CO2 over a decade for an average driver. If your supplier managed the charging for you, the results would be even more dramatic, as you’ll only need to charge up over the best five or six hours (carbon-intensity speaking) per week.

What if I can’t get a smart meter?

Unfortunately, most of these tariffs require you to have a smart meter. Utilities have targets to meet in terms of smart meter installations, so they have a vested interest to install them wherever possible. Smart chargers and chargers connected to smartphone apps can measure car charging in kWh, so there is hope for households who can’t get a smart meter fitted.

How can electric cars support more renewables?

The challenge for green power is that our routines are surprisingly similar – we get up, travel and cook at the same time. We create predictable peaks and troughs in demand. Renewable power, like wind and sun, doesn’t turn up at the right moments to supply these routine demands. The power you actually use on a green tariff may be from fossil sources, which your supplier matches with green energy used somewhere else at another time.

The key to supporting green energy is creating flexible demand. Here’s where EVs are a brilliant help, acting as power stores on wheels. Charging is a relatively moveable demand, as your car is often stationary for many hours at a time, especially overnight. Being smart about when we charge our EVs can help spread the demand across each 24-hour period, reducing the need for high peak power generation.

Smart or managed charging is one form of demand side response. This idea of demand coming to meet supply means more renewable power can be used directly. Excess renewable energy is often diverted into storage and used later, but around 25% gets wasted this way. Sometimes spare energy is even dumped as it can’t be cost-effectively transmitted or stored.

Using more of the energy no matter when it is produced makes renewables more attractive investments. In turn more renewables will be installed and provide more of their cheaper power. Cheaper power then makes electric heating in our homes more cost-effective, enabling a further chunk of carbon to be removed from our lifestyles.

EV tariffs are not just money-saving for the EV driver who switches – the better we get at using electricity when demand is otherwise low, the more efficient and low-cost our grid can become for everyone.