Worked examples: Browse pre-calculated scenarios at ev-tariff, then return here to replace the assumptions with your own figures.
How this calculator works
- The EV charging portion is priced using the off-peak rate and the amount of vehicle energy you expect to buy from the grid.
- Household electricity outside the cheap window is priced at the tariff day rate, which matters if the EV tariff has a more expensive peak rate.
- Standing charges are included so the result compares the full annual tariff cost rather than one headline unit rate.
What can change the result
- Annual EV charging demand
- How much home usage can move into the cheap window
- The EV tariff day rate
- Standing-charge differences
How to read the result
A very cheap overnight rate does not guarantee a cheaper household bill. If daytime consumption is high, test the result with a realistic whole-home split before switching.
A useful way to stress-test the answer is to change the most uncertain input by 10 to 20% and see whether your decision still looks sensible.
Worked example
A household that charges mostly overnight may save, but high daytime household use can erode the benefit if the EV tariff's peak rate is higher.
Frequently asked questions
Should solar generation be included?
Use the amount of household electricity you actually buy from the grid.
Does this model multiple cheap windows?
Use a blended effective off-peak rate.