Vehicle To Grid Savings Fallacy

By Paul Homewood

 

h/t Ian Magness

 

 

 

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Electric car drivers could earn more than £700 a year selling surplus power back to the grid, according to a government-backed study.

More than 300 homes had chargers installed in their homes that enabled them to sell electricity back to the grid that was stored in their car batteries, in the world’s largest trial of its kind.

The study found that consumers could make up to £725 a year when signed up to tariffs that enables a tech platform to take power from the vehicle’s battery for the grid when national supplies were low.

That could fall to £555 when upcoming changes to electricity charges planned by Ofgem come into force.

But installing a vehicle-to-grid charger will currently set drivers back between £4-5,000, compared to around £1,200 for a regular smart charging device.

The authors of the report, known as Project Sciurus, suggested this figure could come down to around £1,000, plus installation, within a year, making the payback period around 3 years.

Energy companies, green groups and EV manufacturers are keen to emphasise the lifetime savings that can be made by switching from fuel to electric cars.

Three energy companies, Ovo, Octopus and Centrica, now offer tariffs that enable drivers to sell their electricity back to the grid. 

https://www.telegraph.co.uk/environment/2021/06/03/electric-car-drivers-could-earn-725-year-selling-power-back/

 

The first point which sticks out like a sore thumb, is the need for a V2G charger, at a cost of £4000 to 5000. This would surely put it out of the reach of most people, despite the potential savings. It is claimed this cost could come down to £1000, but we have heard that old pony before.

But, much more fundamentally, you cannot magic money out of thin air. Car batteries do not reduce the cost of electricity generation, so any “savings” from V2G must be paid for by somebody else. (Or, more likely, the EV driver finds that he is paying more on his tariff instead!)

I have had a closer look at Octopus Energy, who are named in the article.

They pay 5.5p/KWh for electricity exported back to the grid by householders (whether from cars, solar panels or batteries):

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https://octopus.energy/blog/outgoing-update/

 

However, their current electricity tariff charges 18.15p/KWh, so it clearly would make no sense charging the car, only to sell power back!

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It is true that they offer a package called Octopus Go, which charges 5p/KWh at night; however customers are not allowed to be on both schemes at the same time. Anybody using GO only gets paid 3p/KWh for exports.

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The only other option is called Octopus Agile, which charges half hourly pricing for both consumption and exports. There is no guarantee of course that the latter price will be as high as the former, as they are calculated differently. (Exports are based on wholesale pricing). According to their database however, the average export price was 6.7p/KWh in 2018/19, so drivers should not expect to make a mint.

All in all, although it is feasible to charge your car at low off peak prices and export back at a higher price during the day, any savings are likely to be offset by higher electricity costs during the day for other applications.

And all this is before we take account of the effect on battery life from constant charging/discharging.

via NOT A LOT OF PEOPLE KNOW THAT

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June 3, 2021 at 08:15AM

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