How to find the best electricity deal for electric vehicle charging - WATTever

How to find the best electricity deal for electric vehicle charging

Tesla Model 3

In this article, I’ll unpack the essential considerations for electric vehicle owners that are serious about finding the best electricity deal for charging their EV.

Of course, moving from an Internal Combustion Engine (ICE) vehicle to electric means you’ll have much smaller “fuel” costs and be able to predominantly “refill” your car at home. And while electricity is significantly cheaper than petrol or diesel, EV  owners are not immune from paying high electricity charges if they charge at the wrong time or don’t have a suitable electricity plan. Choosing the right retailer and plan for your situation could save you hundreds of dollars.

The formula to get it right

Electricity retailers have made comparing offers a complicated science. Add EV charging into the mix and there can be additional options to consider.

The key to optimising your electric vehicle charging and finding the matching plan is to first determine how you want to charge your EV and the options available in your location.

The primary charging options are:

  • charging from solar
  • charging from storage
  • charging on off-peak Time Of Use tariffs
  • charging on a dedicated controlled load circuit
  • charging on anytime/general tariff

Which options you choose (and you can certainly choose more than one) depends on how you want to prioritise:

  • utility
  • cost
  • emissions

We’ll explain these priorities first and then you can explore the options that meet your needs.

EV Charging Goals
Utility

Utility for EV charging is about ensuring that your vehicle is charged sufficiently to minimise the time you spend charging away from home. In short there are two options achieve utility – charge to 80% every day or plug in only when you need more range for the next trip.

Option one – charging to 80% is self-explanatory and is simplest if you can easily charge at home every day. Option 2 requires more thought – perhaps because you have a long trip and need to charge to 100% or want to charge from solar or can’t plug in every day. WIth option 2, the goal is to ensure your EV is charged sufficiently to allow you to do the next day/days driving. If you expect to drive 60km the next day then you should ensure your EV has enough range to do that plus a buffer for unexpected trips. That should mean a range of at least 100km. If those unexpected trips aren’t just an extra 20km trip to the shops, picking up kids etc and involve you driving out of town to see family or for a work trip of 100+km extra then you’re probably better off charging your EV to 80% every day so you have a much bigger buffer.

Cost

EV owners are usually looking to minimise their charging costs to recoup the higher purchase cost of an EV. Charging at a low cost if the most important aspect in reducing  the running costs of an EV. Home charging is the cheapest and most convenient solution for most people however public and workplace charging can also be low cost and depending on location, equally convenient. Public fast charging is the highest cost solution but will still be cheaper than purchasing fuel. Public fast charging rates in Australia are around 40c per kWh – the equivalent of ~$1 per litre.

Emissions

The third goal for charging is to reduce the emissions associated with the generation of the electricity used to charge your EV. For those concerned with the impact of air pollution and carbon dioxide emissions, charging from solar or GreenPower provide the lowest possible emissions. Using grid power, whether general, off-peak tariff or controlled loads, the intensity of emissions will depend on your location and the emissions of generators providing supply. Generally with increasing solar penetration rates in Australia, the middle of the day offers lower emissions. States such as Tasmania and Victoria have significant hydro, wind and solar assets and have significantly lower emissions associated with electricity generation than states like NSW, QLD and VIC which are heavily reliant on coal and gas generators.

EV Home Charging Options

While there are different technical options to charging your home – fixed charging station, portable charging station etc, in this section we’ll focus on where the electricity comes from and how you’ll be charged for it. You can use one or many options here, whatever best suits your needs.

Charging with Solar

Solar from your own rooftop is probably the cheapest option to charge your EV as feed-in tariffs are generally lower than even off-peak electricity rates for most electricity plans. This means that if you’re vehicle is home for some of the daytime and you have sufficient excess solar you can charge your EV from the sun.

Charging on off-peak Time Of Use tariffs

Time of Use tariffs are available in most states and have different rates at different times of the day. The reason why they can be a compelling option for EV owners is that they off off-peak tariffs which are usually signifcantly cheaper than the general/anytime tariffs where the same cost applies throughout the day. Off-peak times are fairly consistent across Australia dnare usuall 10pm-7am 7 days per week. You can browse our Time Of Use periods page for the off-peak times for your network.

Charging on a controlled load tariff
Controlled load tariffs allow EV owners to connect a fixed charging station in their garage via a dedicated circuit to the meter box and access a lower electricity rate. The circuits are controlled by the electricity network in the sense that they are turned on and off within a certain time window and provide a minimum number of charging hours per day – usually between 6-16 hours. Controlled load tariffs are only available in specific states. Our Home EV Charging Rates page shows the networks these tariffs are available.

 

Charging with Storage
If you’ve added storage alongside your solar PV system then you have access a low emissions energy source. Storage works well to provide consistent charging during the day without having import power from the grid and will certainly increase the portion of solar you’ll self consume. It’s unlikely to be a cheap solution versus solar, off-peak or controlled load charging but if you’ve already made the investment then using it will, in most cases result in lower electricity bills.

 

EV Charging Costs

To understand the costs associated with EV Charging through the solar, off-peak etc  see our article Home EV Charging Rates in Australia.

Comparison to petrol/diesel

Average EV consumption is 12-24kWh/100km for passenger vehicles. If we assume a conservative 20kWh with off-peak charging at 20 cents that means a cost of $4 per 100km. COmpared to an ICE vehicle achieving 8l/100km at $1.50 per litre, the per litre equivalent cost of charging your EV is about 50 cents per litre. Drive more efficiently, or have a lower electricity rate and you can do get that down to around 30c per litre. Arguably if you charge 100% from solar (once your panels have paid for themselves) and you’re not receiving a feed-in tariff then your charging costs will be zero.

There are too many options – what do we recommend?

As an owner of electric vehicles from more than 10 years, I’ve tried pretty much means of charging my EV at home.

So what would I recommend?

  1. Charge your EV from the cheapest electricity source you have – that’s usually your own solar or a time of use off-peak tariff. Controlled load tariffs are an alternate option but the time periods of charging are out of your control.
  2. Have a backup charging option (if your primary option is to charge from solar/battery/controlled load) that will allow you to charge to 100% for the days when you need it.
My charging setup

My home has a 10kW solar PV system and is on Ausgrid’s Time Of Use tariff providing me with a 9 hour (10pm-7am) off-peak period every day of the week. I pay a 16 cents off-peak rate and receive a 20 cent feed-in tariff. This means it’s cheapest for me to charge my EVs overnight and export my solar. Nine hours is more than sufficient to charge my EV to 80 or 100% every night even on a common 10A wall socket. Occasionally, we need to charge in the middle of the day if we do a long drive in the morning and then head out again in the afternoon/evening. In this case I’ll charge from my solar and solar/battery of it’s cloudy.

We’re fortunate enough to have battery storage but with solar and off-peak charging it isn’t necessary to use it to keep costs low. From an emissions perspective, whether  you charge your EV from solar or from the grid, the result is the same – my solar produces ~35kWh of renewable electricity each day on average. Whether I use that or my neighbour does, doesn’t matter. Currently we export about twice the amount of electricity as we import so our total household usage is more than covered by the renewable energy we generate.

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