How much does it cost me (and the planet) to charge my car?

Electric vehicles Apr 27, 2020

Our customers often ask how much money and carbon they can save by choosing a smart charger like Hypervolt, so we’ve done the maths and put together a simple walk through with some quick facts to drop over dinner.

In this blog we’ve based our calculations on an “Average Joe” or “Medium Mel”, who drives 7,600 miles per year, and our assumptions are available here.

To find out how much Hypervolt can save you, get in touch! We’re here to help and would love to hear from you.

Quick facts summary:

  1. The CO2 emissions from driving a petrol or diesel car for one year weigh the same as the car itself.
  2. The "fuel" for a typical electric car costs three times less and emits three times less CO2.
  3. Including manufacturing, total lifetime CO2 emissions for an electric car in the UK are 2.5x lower than a petrol or diesel car.
  4. Charging using Hypervolt and time-of-use tariffs is up to 70% cheaper than an equivalent non-smart charger, and 10x  cheaper than petrol or diesel.
  5. Solar charging with Hypervolt Sense reduces demand on the electricity grid during "peak" times, saving carbon and saving you money.
  6. Hypervolt uses clever algorithms to lower your carbon footprint by up to 25% vs other chargers.

Typical Electric vs Average Fossil Fuel

Every 100 miles, the average new petrol or diesel car registered in 2019 uses 8.5 litres of fuel, costing around £1.30 per litre, and emits 20kg CO2.

That means driving 7,600 miles in one year you’ll spend around £840 on fuel and cause 1,500kg CO2 emissions.

It’s hard to visualise carbon emissions, but that’s a sooty cloud of smog that weighs roughly the same as the car itself, every year. Crikey...

Quick fact 1: The carbon emissions from driving a petrol or diesel car for one year weigh roughly the same as the car itself.

A typical fully-electric car new in 2019 uses 30kWh per 100 miles, and therefore 2,280kWh per year - equivalent to about 13kWh of charging every other day.

The average UK electricity tariff is £0.16 per kWh, and the average carbon intensity of electricity on the UK grid in 2019 was 0.25kg CO2 per kWh.

So Medium Mel will spend around £365 per year (£1 per day) and cause 570kg CO2 emissions charging her electric car. That’s a huge decrease - not to mention the improvement in urban air quality.

Quick fact 2: A typical electric car uses almost three times less in both “fuel” costs and carbon.

Those with a keen eye may also have noticed that average CO2 emissions from new petrol and diesel cars have been creeping up in the UK every year since 2015, while the carbon intensity of electricity on the grid is going down. So the gap will get wider very quickly.

And let's put paid to another myth here: while manufacturing an electric car does emit slightly more carbon than a diesel or petrol car, this is far outweighed by the emissions from driving with petrol or diesel, even with a high carbon power grid.

Quick fact 3: Manufacturing an electric car emits slightly more CO2, but this is far outweighed by driving emissions from petrol or diesel - phew!

So far so good: electric cars are miles cheaper to run and miles better for the environment on average. But can you do better than that?

We’re confident you can.

Even cheaper, greener charging with Hypervolt

Hypervolt Home is a smart charger with many neat and easy-to-use features that will help you save even more money and carbon. We’d like to show you three in particular…

Time of use tariffs

First up, many electricity suppliers now offer special eletric vehicle tariffs with low rates, some as low as 5p per kWh. Some are even offering the first 2,000kWh of overnight charging per year for free! (That's ~10.5 months of free driving for Average Joe.)

Hypervolt customers can use our app to select their preferred charging mode and match charging to their low tariff rates. At 5p per kWh, one year of charging would cost Joe £115.

That’s a saving of £250 (70%) versus using an equivalent non-smart charger plugging in around 6pm, and a whopping £730 (86%) cheaper than fossil fuels. Or, with the first 2,000kWh free, it could cost as little as £14 per year - don’t even get us started…

Of course you could get these rates using a standard charger, but Hypervolt does the work for you and saves running outside in slippers at midnight.

Quick fact 4: Charging using Hypervolt and time-of-use tariffs is up to 70% cheaper than an equivalent non-smart charger, and 10x cheaper than petrol or diesel.

Electric vehicle tariffs are typically matched with 100% clean electricity sources, meaning that while you’re still using grid electricity your money goes directly to renewable energy providers.

Solar charging

Next, Hypervolt Sense is an optional extra feature for Hypervolt Home customers that senses when your solar panels are generating more power than you’re currently using at home. This surplus power would normally be “spilled” to the grid for around 5p per kWh.

With Sense your Hypervolt kicks in automatically to soak up all that excess solar and charge your car with 100% clean home-grown electricity. What could you save?

For every kWh used to charge your car instead of exported to the grid you save the difference between your solar export tariff (~5p per kWh) and the amount you’d pay to charge your car from the grid (~16p per kWh). A typical 12 panel (3kW) solar installation in the UK generates 3,000kWh per year, of which typically 70% is exported to the grid. Assuming all that excess solar can be stored in your car, this adds to £230 saved per year, not bad for a mighty little gadget.

And the boost to your green kudos? Well, Sense reduces the carbon intensity of the electricity powering your car, which feels great. Medium Mel is in fact saving ~750kg CO2 per year with her solar overall. But if she doesn't use that excess solar power somebody else on the grid will. After installing Sense, that 'somebody' has to get their power elsewhere, so does it reduce emissions overall...? Yes! Using Sense to charge your car while it's sunny during the day instead of in the evening reduces demand at "peak" when grid power is higher carbon, saving around ~100kg CO2 per year in addition to the 750kg saved by the solar energy itself. Nice one!

Quick fact 5: Solar charging using Hypervolt Sense reduces pressure on the electricity grid during "peak" times, saving carbon and saving you money.


Saving the smartest til last, HyperGreen is a new feature we’re very excited about.

CO2 emissions from our electricity grid vary throughout the day and night, for example due to weather conditions or whether the Queen is making a speech.

HyperGreen uses clever algorithms and forecasts to match your charging to the periods of lowest carbon emissions on the grid. Opting in takes one touch of a button, and all you need to do is plug in when you get home. Hypervolt will then pick the greenest times to charge throughout the night, ready for the next morning, and track how much carbon you’re saving.

Throughout 2019, our average Joe would have avoided up to 140kg CO2 emissions using HyperGreen, or caused 25% less carbon emissions than charging an equivalent amount in the evening every other day.

That’s a cloud of smoke that weighs the same as a sumo wrestler, every year. What about HyperGreen compared to petrol or diesel… avoided carbon emissions the weight of a sumo wrestler driving a car?

Quick fact 6: Hypervolt uses clever algorithms to lower your carbon footprint by up to 25% vs other smart chargers.

At Hypervolt our mission is to accelerate the World’s uptake of electric vehicles, starting with the UK, by providing the most affordable, smartest and greenest chargers on the market.

To find out how much you can save, get in touch. Our team of experts are happy to help.

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