The Cost of Charging your EV at Home
Whether you're considering purchasing a fully electric car or plug-in hybrid, one of the key incentives for becoming an EV owner is the opportunity to reduce your fuelling costs over that of a vehicle with an internal combustion engine.
However, estimating your potential cost savings isn’t always straightforward. Educational online resources like Drive Electric offer helpful insights like the average cost of electricity for using public charging stations and charging at home, but In practice, these costs will vary greatly depending on your charging habits. This includes charging location, your unique electricity rates, and EV charging system.
To help you build a more accurate picture of the costs of charging your EV, we’ve answered a list of frequently asked EV charging questions including methods to lower your EV electricity bill while reducing reliance on non-renewable electricity sources.
Where is the cheapest place to charge an electric vehicle?
Despite some free public charging options around New Zealand, the most convenient and cheapest place to charge your EV in the long term is at home. Home charging allows you access to free renewable energy generated from home solar systems and equally important ‘free power hours’ which are becoming common in EV-tailored electricity plans offered by retailers.
Not every EV driver owns a home solar system, and these electricity cost savings will vary depending on the time of day and time of year you’re charging from solar. So for this article we will focus on choosing and optimising your electricity plan. If you want to learn more about the benefits of solar EV charging you can read our article on Solar EV Charging.
What are the best electricity rates for EV home charging?
In New Zealand, there's a range of different plans (tariffs) whose electricity rates are structured depending on a given time of day / electricity demand. These can be as simple as a single electricity rate at any time or as complicated as 4 different rates that may also differ between weekdays and weekends. Here is an example of three common types of New Zealand tariffs.
- Anytime rates: A single 'All day, Every day' cost per kilowatt-hour rate that does not fluctuate during the day, night, or weekend.
- Day / Night rates: Two separate electricity rates with the potential to customise their start and end times. These rates may apply across all seven days of the week, or sometimes the whole weekend is priced at the lower ‘Night’ rate.
- Peak / Off-peak / Night rates: Three separate rates with the potential to customise start and end times. Again, these rates may apply across all seven days of the week or there may be no ‘Peak’ rate over the weekend.
There is no perfect tariff for every EV owner’s situation, but there are some key factors to consider when reviewing your electricity rates to maximise EV charging cost savings.
1) What are the cost/kWh rates offered between 9:00pm-7:00am?
Regardless of the structure of an electricity tariff, these are commonly considered the ideal hours for charging your EV overnight. This period is often when cheaper and less carbon intensive electricity is on the grid and will determine a majority of your EV charging costs at home. So be sure to spend time reviewing the electricity rate(s) your tariff offers during this time.
If you drive your EV more frequently on the weekends also check if night rates differ between weekdays and weekends as this could vary your weekly charging costs. Even if you have a simple “anytime” tariff, it doesn’t necessarily mean it’s a bad choice for EV drivers as these plans may include free hour(s) of power overnight instead of a specific night rate.
2) Does the tariff include recurring free power hours?
If your current electricity plan doesn’t include recurring free power hours, it might be worth considering switching to one that does. For EV drivers, this is the equivalent of a petrol station offering free gas at certain times of the day. Along with home solar, maximising these free power hours is the cheapest way to power your EV at home.
For instance, Electric kiwi’s Movemaster plan includes a free hour of off-peak power that can be used daily between 9:00am to 5:00pm or 9:00pm-7:00am.
How valuable are free hours of power for electric car charging?
Depending on your situation, there’s potential to reduce your EV charging bill to $0 per night and still fulfil your daily charging needs.
Consider the average New Zealand daily commute. According to Drive Electric, this is around 25-35 km/day. So, most EV drivers need to fill up their car battery enough to replenish that equivalent range daily. The challenge becomes how much range can be replenished within those free power hours. This is where fast charging speeds become more important.
A conservative estimate to charge the equivalent of 10km of range translates to roughly 1.8kW of power for 1 hour. If you were to have an electrician install an AC fast charger at home such as a common 7.4kW rated unit, you could add up to 40km of range to your car's battery in a single hour.
So within a single hour of charging time at home with a fast EV charger, there’s the potential to fill up the equivalent range of your daily commute for free or recover a full charge overnight during cheaper off-peak or overnight rates. If your commute is more than the average, you can use these charging time estimates to help calculate your costs with a given electricity plan.
To understand more about charging speeds, see our article How long to charge my EV?
Tracking the cost of charging your Electric Vehicle.
It’s important to understand the electricity tariffs available to EV drivers but also to understand your current charging habits. If you’re not setting a charging schedule to make the most of your electricity rates, then you’re missing out!
That’s why we created an intuitive Electricity Pricing tool for Evnex customers to keep an accurate record of their charging costs, and a breakdown of these costs unique to each driver’s tariff. By selecting your tariff type, electricity rates, and free power hours or solar connection you can review your charging costs at a glance and know whether you’re charging within those cheaper electricity rates.
At Evnex, we empower you to charge your EV from cheap and clean energy while minimising impact on the grid. If you have any questions about the costs of charging your electric vehicle at home, let us know. Our local team of charging experts is here to support you along your EV charging journey.