Nissan Leaf - Charging on Economy 7

Monday 26th April, 2010
After reading this piece, please see my updated "One Year Later" article.

There's still some debate over how much it costs in electricity to fully charge a Nissan Leaf from empty. Originally I was told "something like 1.20 Euros" but this didn't apply in the UK so I did the maths.

The Nissan Leaf UK tour came to the O2 last week and a group of journalists and fleet reps came to see the new car and learn about the stats. Some correspondents told me that Nissan were still claiming £1 for a full charge, so I probed further.The end result was that @UKNissanLeaf responded: "We estimate the cost to fully charge a LEAF overnight would be in the region of £1 to £1.50 using low rate Economy 7 electricity".

So there we have it. To get charging costs as low as the claimed figures, you may need to be on a different retail tariff for your electricity. But how will that affect your overall electricity bills? Read on...

An Economy 7 tariff offers cheaper "overnight" electricity to customers, usually from 10.30pm to 12.30pm and then from 2.30am to 7.30am. Seven discounted hours, hence the name Economy 7. As demand is much lower then, there is a much lower cost for the wholesale electricity you are being supplied and this is passed on to you, the consumer.

Looking at a current published price with a major supplier, their Economy 7 cost is 5p/kWh - a saving of around 50%. So on first inspection, you could very wrongly believe that it would cost you 5p x 24kW = £1.20 to fully charge the Leaf overnight, instead of the previously calculated £2.40. But, on closer inspection, there are MAJOR hidden costs here.

Using figures I have to hand for EDF electricity, on their STANDARD tariff I'm seeing a cost of 17.15p/kWh for the first 900kWh followed by a cost of 11.76p/kWh for the remaining units. Switch that to Economy 7 and it's a very different story. As you've agreed to use electricity overnight, then your day rate rockets upwards. 17.15p/kWh becomes 20.30p/kWh and not for 900 kWh of units, actually for the first 1000. After that the day rate clocks in at 12.44p/kWh.

So yes, the Leaf will be cheaper to charge overnight but your existing electricity costs could rise something like 20%.

The first 1000 units on the standard tariff would cost you 900 x 17.15p + 100 x 11.76p = £166.10

The exact same electricity on economy 7 would cost you 1000 x 20.30p £203.00 an increase of £36.90

But that only covers the first 1000 units, my bills in comment 1 here show a usage of around 2000 units per quarter - let's call it 7000 units per year. So that's 6000 more units at the increased Economy 7 day rate.

On Economy 7, these will cost me an extra 0.68p/unit, or 6000 x 0.68p £40.80 per year.

So, overall, switching to Economy 7 might cost me 36.90 + 40.80 = £77.70 extra, each year...just so I can charge my car a bit cheaper?

With a saving of only £1.20 for each charge, I'd have to fully charge my Nissan Leaf 65 times a year to break even and save the increase in costs by switching my electricity to the new tariff.

Correct me if I'm wrong, the Nissan Leaf is a low range car aimed at low mileage drivers who apparently don't like petrol stations. Are they really going to need to fully charge their car more than once a week? If you believe the hype, 65 full charges would equate to a potential distance of 6,500 miles a year. Seems a lot for the aims of this car.

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