Before deciding when to charge first check on how long you will need to be charging your EV for.
There are three common charging speeds, 2.3 kW chargers that connect to a regular wall outlet, 7 kW fast wall chargers, and high power 3 phase chargers at 11 kW or more.
At 7 kW or faster, most drivers will only need a couple of hours of charging each day, and will be quite flexible in what time of day they charge and you can maximise how much you can charge from rooftop solar. If you're charging from a regular wall outlet and driving above average kilometres you might need some longer charging sessions with less flexibility on starting times.
For more details see our article on home EV charging speeds.
If you have rooftop solar and your EV is often home during the day, in most cases it will be the cheapest and greenest energy you can get. Charge HQ can help you automate this.
Once you've ticked off charging from your rooftop solar the next step is to consider the energy plan you're on with your electricity retailer.
If your priority is to minimise your charging cost the best time depends on your tariff type:
If you are on flat rate, you should still avoid charging during the early evening which is often a peak demand period, in the long run you'll pay more for power if a lot of EV drivers do this.
As discussed in our article on factors to consider when to charge your EV, charging during periods of high renewables helps reduce emissions from electricity generation and in the long term should help bring down power prices.
Periods of high renewables change on a daily and seasonal basis, and the relative levels vary significantly across different Australian states. Ideally EV charing times will be automatically controlled and scheduled on a daily or even hourly basis to align with periods of maximum renewable generation. This is where we're headed with Charge HQ but for now some charging still needs to operate on a regular schedule.
If you want to schedule charging from the most renewables:
For Queensland, New South Wales & Victoria:
For South Australia:
The recommended times are derived by considering share of generation from renewable energy as published by NEMlog.