Choosing an EV tariff.

jhobson

I was faced with working out which EV tariff to go to, so I created a spreadsheet to model the key variables like your EV mileage, average Miles / kWH, % charging at home, your total domestic usage, how much is already in the off peak period and how much you can “load shift” into the off peak period.

I thought it might be helpful to other people who are faced with the same choice, so you can find it here:



https://onedrive.live.com/view.aspx?resid=A6C378216980334F!359&authkey=!AAuPh4NSIHOTpJE





It applies the input variables to the available EV tariff rates to calculate what your total costs would be with each supplier. You can compare these with a couple of representative variable and fixed rates , or enter your own current supplier's rates.

You can rank the suppliers by the saving (or extra cost). 

It shows you the results in a table and in a chart and finally gives you an idea of the pence per mile driven cost compared to an ICE car.



There is help available in cell notes throughout the worksheet.



It is written using Microsoft Excel online / Onedrive which has some quirks compared to standard desktop Excel. To protect the integrity of the worksheet and stop anyone accidentally breaking it, the share link above is read-only. 



If you want to use the worksheet to enter your own parameters and / or supplier rates you will need to make a copy.  If you are a Onedrive user and are logged in you can simply duplicate it. If not you can simply chose File -> Save As to download  and store a local copy that you can then open in your favourite spreadsheet programme. You can download as .xls or ODS (OpenDocument Spreadsheet) format.



Please note that the spreadsheet is provided without warranty at no cost to you, in the spirit of sharing, and you should be careful to check the results yourself before relying on them to make any financial decisions.

Any comments or corrections are of course welcomed.

I hope it is useful to some of you!

John

FreeBear

Would be handy if the daytime & charging rates were displayed (and perhaps compare against Octopus Agile).

Got myself a charger installed, but as EV usage is minimal at present, there is no advantage to moving away from the Tracker tariff.

jhobson

FreeBear said:

Would be handy if the daytime & charging rates were displayed (and perhaps compare against Octopus Agile).

Got myself a charger installed, but as EV usage is minimal at present, there is no advantage to moving away from the Tracker tariff.

The daytime (peak) rates and the nighttime (charging) rates are displayed in the tariff section.

Direct comparison with Octopus Agile would be a bit challenging as you can't know what the rates are in advance as they change every half an hour, based on the wholesale price of energy.

Gerry1

You'll get a shock when you have to charge away from home.  Sainsbury's and Waitrose charge an eye watering 85p/kWh which is about twice the marginal cost of using petrol.

Presumably Waitrose also charge the parking fee as well.  I shan't be getting a pure EV anytime soon !

Veteransaver

Gerry1 said:

You'll get a shock when you have to charge away from home.  Sainsbury's and Waitrose charge an eye watering 85p/kWh which is about twice the marginal cost of using petrol.

Presumably Waitrose also charge the parking fee as well.  I shan't be getting a pure EV anytime soon !

Think I've charged a total of about 100kWh at public chargers in 4 years! If you can charge at home its pretty insignificant 

jhobson

Gerry1 said:

You'll get a shock when you have to charge away from home.  Sainsbury's and Waitrose charge an eye watering 85p/kWh which is about twice the marginal cost of using petrol.

Presumably Waitrose also charge the parking fee as well.  I shan't be getting a pure EV anytime soon !

You seem to be ignoring the bit where most of people's charging is done at home at a tenth of that cost if they are using an EV tariff.

By my calculation the blended energy cost of my usage of home and public chargers is under 5p a mile. Comparing that with my previous BMW diesel which works out at about 16p a mile I am quite happy with my pure EV!

born_again

To throw a spanner in your chart workings 🤷‍♀️

Remember that on IO that you get daytime slots as well as the off peak 22:30 to 05:30. These daytime slots are also @ 7.5p & include whole house usage. Only had 2 slots that charged overnight every other (48) have been during peak time @ off peak rate. 

Example.
£4.42 cost for 58.9kWh into car between 10:18 & 18:56. So that would be a saving of 22p per kWh of house usage as well. House usage average is 6kWh so a £1.32 saving in this session.

So to maximise this. We shift as much house usage while cars re charging.

jhobson

born_again said:

To throw a spanner in your chart workings 🤷‍♀️

Remember that on IO that you get daytime slots as well as the off peak 22:30 to 05:30. These daytime slots are also @ 7.5p & include whole house usage. Only had 2 slots that charged overnight every other (48) have been during peak time @ off peak rate. 

Example.
£4.42 cost for 58.9kWh into car between 10:18 & 18:56. So that would be a saving of 22p per kWh of house usage as well. House usage average is 6kWh so a £1.32 saving in this session.

So to maximise this. We shift as much house usage while cars re charging.

Well I wouldn’t really call it throwing a spanner in the works - it’s impossible to quantify the benefit of that and it’s at least partially offset by the amount you pay at peak when plugging in while Octopus work out what you are doing ;-)

Any estimation of cost is going to be approximate after all, and if this were so regular it had a really major impact it would probably end up being a different tariff wouldn’t it? 

Thanks for the feedback though 

MWT

born_again said:

Remember that on IO that you get daytime slots as well as the off peak 22:30 to 05:30.

That should be 23:30 - 05:30

born_again said:

Example.
£4.42 cost for 58.9kWh into car between 10:18 & 18:56. So that would be a saving of 22p per kWh of house usage as well. House usage average is 6kWh so a £1.32 saving in this session.

That is not to be considered as 'typical' of what IO will deliver to the vast majority of customers, but it is possible to manipulate the system to deliver that result, but that ability will go away before too much longer so it would be wrong to let people believe that was a reasonable expectation

The intention is to allow customers to select a 'ready' time between 04:00 - 11:00 and that can indeed include some time periods outside the standard off-peak period, but not to the degree suggested in this post...

Gerry1

jhobson said:

Gerry1 said:

You'll get a shock when you have to charge away from home.  Sainsbury's and Waitrose charge an eye watering 85p/kWh which is about twice the marginal cost of using petrol.

Presumably Waitrose also charge the parking fee as well.  I shan't be getting a pure EV anytime soon !

You seem to be ignoring the bit where most of people's charging is done at home at a tenth of that cost if they are using an EV tariff.

By my calculation the blended energy cost of my usage of home and public chargers is under 5p a mile. Comparing that with my previous BMW diesel which works out at about 16p a mile I am quite happy with my pure EV!

It won't be so attractive when duty is added to the kWh price for home charging.  The present situation is merely the introductory offer.  At some point it'll be withdrawn just as the Congestion Charge exemption for the Prius was.

The government won't be content to forgo indefinitely all the duty collected on petrol and diesel sales.

MWT

Gerry1 said:

It won't be so attractive when duty is added to the kWh price for home charging.  The present situation is merely the introductory offer.  At some point it'll be withdrawn just as the Congestion Charge exemption for the Prius was.

The government won't be content to forgo indefinitely all the duty collected on petrol and diesel sales.

... meanwhile, 6 years into my EV ownership I'm still enjoying the benefits that a smart meter has allowed me to enjoy, and fully expect to continue saving for some years to come.

You can continue to warn about what might happen 'at some point' or just get on with taking advantage of what is available right now.

Loving the smart meter, EV tariffs, Solar PV and home battery, haven't paid over 8p/kWh for any electricity for the last 3 years...

I'll take that over worrying about what might happen 'at some point'...