Savings Assumptions & Calculations

The calculations of our potential savings must be based on a number of assumptions. What are they?



  • EV annual mileage: 10,000 miles
  • EV-related annual energy demand: 4,109kWh
  • EV kWh per km: 0.171
  • Charger Rating: 7kW
  • Charger Efficiency: 0.9

House & Tariff

  • Household annual energy demand: 2,900kWh
  • Standard Variable Tariff (SVT): Octopus Energy April 2023 
    • 33.21p/kWh Import
    • 51.32p/day Standing Charge
  • Economy 7 Tariff: Octopus Energy April 2023
    • 43.25p/kWh Peak Import (0730-0030 hrs)
    • 17.24p/kWh Off-Peak Import (0030-0730 hrs)
    • 51.42p/day Standing Charge


  • Solar system: 4kWp
  • Solar annual generation: 3,633kWh
  • Solar cost inc. installation (estimate): £4,500
  • Solar Export Tariff: Octopus Energy Outgoing Agile 2021

CO2e Intensity

  • Based on National Grid Carbon Intensity Forecast (2022)


Energy Savings from Switching Tariff

Having made the switch to EV, customers can save up to £331 per year (15% of their total energy bill) by switching from a Standard Variable Tariff (SVT) to a static Time-of-Use Tariff such as Economy 7 and scheduling their EV to charge during off-peak hours (typically 12am – 7am). This will also help save 143kgCO2e each year

Energy Savings from Installing Solar

After installing a 4kW solar system, customers can expect to save up to £636 per year. These savings are on top of the savings made from switching tariff. Their carbon footprint would also decrease by 0.7 tonnes per year

Total Potential Energy Savings Per Household

Combining the tariff switching benefit with the solar benefit, customers can save up to £967 per year on their energy bill (45% reduction). If they were to schedule appliances such as the dishwasher and washing machine to run overnight during off-peak hours, customers can expect to save an additional £40 – £50 per year*. This would provide a total potential energy savings benefit of over £1,000 per year (over 45% reduction on the original energy bill). It would also cut their carbon footprint by 850kgCO2e per year.

*note Powerverse cannot automate overnight scheduling; the customer would need to do this manually. However, Powerverse could quantify the benefits for the customer and guide the customer to ensure they secure these additional savings.