What is the Evenergi total cost and environmental impact rating engine?
The Evenergi total cost of ownership engine was built with funding from Australian Renewable Energy Agency (ARENA)* in association with ARENA, SA Government and South Australian Power Networks, and input from several major automotive and energy groups. It aimed to be one of the first products to help consumers understand what it means to buy an electric vehicle and then power it with renewable energy sources.
* Although the project was funded by ARENA, they take no responsibility for the accuracy of the product.
What is the total cost rating system?
When you buy an electric vehicle your upfront costs may be a little higher, but generally, your running costs will be a lot lower. There are many factors that make up the cost of owning and running a vehicle. To simplify this we have created a rating system that provides a single number to compare - the c/km (or mile).
This number incorporates all the purchasing and running costs along with the loss of value that the car sustains over the period of ownership.
This is an early version of the product and we are constantly seeking to improve it. If you have any suggestions, queries or corrections please get in touch.
How is it calculated?
To calculate the cost to own we have included the current retail prices of vehicles and the manufacturer guidance on servicing and maintenance costs. On-road costs are calculated based on local (i.e. state) taxes and levies and energy prices are based on the standard pricing of the largest energy company in an area.
We use a standard default energy usage profile for the vehicle, however this can be modified using advanced options to update the size and configuration of your home energy appliances. You are also able to add solar, (which takes into account local feed-in-tariffs) and add a battery, which determines the amount of use for charging the car using the energy profiles you have created.
For driving, we use standard driving and home garaging profiles, however you are also able to update these in advanced settings based on the amount that you garage your vehicle at home, and how far you drive in an average year.
How does owning solar improve the benefits of EV ownership?
In our total cost of ownership model, we are able to add solar and battery usage to profiles and it calculates the cost to own and carbon intensity based on the source of power consumed by the vehicle.
The benefits of solar ownership for an EV driver depend on the coincidence of charge times with the times when solar is generating energy along with the capacity for the solar to be used to charge the car at those times (i.e. that the speed of charging is less than or equal to the speed of solar generation). If you assume that the capital expense of the solar is a separate investment to the electric vehicle, then the power generated at those times will be effectively free for the vehicle. For each kW that is used during those times the business case for owning an EV will improve.
Given the high power rating of a 7.2 kW charger used in the scenarios above, the average 5.82 kW system will only be able to fulfil part of this demand, and only on sunny days. To maximise benefit, a vehicle will need to be at home, and charging at a rate to match the power output of the solar system. To maximise this benefit some owners will choose to charge with a slower charger or get a generation following product which charges in line with renewable energy generation.
If we think about the value of the battery, essentially the car receives cost or environmental benefits only after the battery has provided power for home usage. The battery will need to have some power left to contribute to the car charging. Like solar above, depending on the size of the battery, it may only have the capacity to provide some of the energy required by the charger assuming it needs 7.2 kW all at once.
How is the carbon impact rating calculated?
The carbon impact is calculated on a well-to-wheel basis. This means it includes tailpipe emissions, costs of delivering the fuel from drilling (or producing it at a generator in the case of electricity) and then the carbon intensity of the electricity grid. The carbon intensity is changed for each region. The calculator currently supports most states in Australia and the UK.