Our methodology

Charging cost

Battery energy in kWh equals usable capacity multiplied by the percentage-point change in charge, divided by 100. Grid electricity divides battery energy by charging efficiency expressed as a fraction. Multiplying by the VAT-inclusive unit rate gives estimated charging cost.

The estimate excludes standing charges, installation and public charging. The prefilled values are illustrative inputs, not measured market averages.

Charging time

We take the minimum of the vehicle AC limit, charger power and optional property limit. Delivered power multiplies that minimum by efficiency. Dividing required battery energy by delivered power estimates hours.

This simplified AC model assumes constant power. Cold batteries, tapering, scheduled pauses and load management can increase the time. Ties between limits are shown together.

Tariff comparison

Annual miles divided by miles per kWh estimates driving energy. We multiply by home charging share and divide by charging efficiency to estimate home EV grid consumption. Household electricity excludes EV consumption.

EV and household energy each use a separate off-peak share. We add daily standing charges for 365 days, then compare with the entered flat-rate scenario. A negative saving means the entered tariff costs more. This is not a forecast of dynamic prices.

Charger matching

We exclude chargers outside your country, incompatible known supply phases and missing required supplier integrations. Scores award 20 points for meeting the AC limit, 25 for requested solar capability, 20 for hardware budget, 10 for cable preference, 15 for a listed supplier integration and 10 for load balancing.

Scores depend on your preferences and available evidence. Unknown prices do not earn budget points. Installation costs are separate. Warranty and grant eligibility need contextual review and are not included in the score.

Corrections and limitations

Check source dates before acting. We aim to make assumptions inspectable and correct errors at the source. The same calculation functions power the tools and automated tests.