A newly released report from Queensland’s government owned network operators Ergon and Energex provides some fascinating insight into how EV owners charge their cars, and it points to the fact that EV owners are happy to be flexible, and charged by the sun.
It should be noted that the report covers a total of only 167 EVs that remained for the full trial period conducted by the two networks (some dropping out due to sale of the vehicle, dealers forgetting to reinstall the data collection device after a service … or the car being written off!).
Also, given the cohort were the earliest of early adopters (sometimes separated out as the first 2.5% being an ‘innovators’ group separate to ‘early adopters’), they are not entirely representative of the general car owning public.
For instance, 77% of participants had PV solar on their homes (compared to an overall 33.3% in Queensland) and 19% also had a battery energy storage system in addition to solar PV. (Compared to 0.49% of residential premises in Queensland). Seven of the households even had two EVs!
As seen in figure 1, like EV sales over the last few years, almost 50% of the cars in the trial were the Tesla Model 3. There are now more models on offer, although Tesla has retained its grip on market share by sheer weight of numbers.
One particularly interesting finding came from a study where participants were encouraged to change their charging behaviour around peak times between 4pm-9pm, and during the day to assist with soaking up excess solar PV generation.
The trial involved instructions to either ‘charge your EV’ or ‘do not charge your EV’ during specific times. (Participants could opt out of any individual event).
These charging or disconnection events were called at different times of the week and weekend with different notification lead times, durations, and incentive amounts. Participants were found to be more likely to respond to ‘charge their EV’ requests rather than ‘do no charge’ ones.
Interviews after this part of the trial indicated that participants found doing so was easy, as well as indicating the event requests did not interrupt their day-to-day lifestyle. Ergon/Energex noted in the report that whilst being recognised as an innovator cohort, this highlights the potential for managed charging going forward.
Another interesting finding was that only 62% of charging energy was provided at home – significantly less than the ‘80% to 90%’ usually stated as the average home charging percentage.
Unsurprisingly though, ‘small’ EVs with small batteries (such as early Nissan Leafs, Mitsubishi iMiEVs and most PHEVs) still did most of their charging at home.
Overall though, the conclusions pretty much fitted with what we in the EV sector hear anecdotally from EV owners as they get used to their new ‘toy’ and its recharging needs.
First-up: Ergon/Energex found EV owners take easily to the new ‘refuelling’ regime of home charging. EV owners are also willing to have their EV charging managed, so long as there is a benefit to them (i.e. a time-of-use tariff can impact charging behaviours) and EV owners felt that their EV amenity was not compromised by charging at the best time for cheap electricity rather than as soon as they arrived home.
Ergon/Energex also found that as EV owners become more familiar with their EVs, their charging profiles altered with fewer deeper charging sessions and the starting state-of-charge (SOC) becoming lesser over time.
Another finding from the qualitative interview phase was that EV charging does not appear to be a consideration in the decision-making process when purchasing an EV. In this regard, the report suggests that more information needs to be made available to EV purchasers in relation to charging expectations and options.
The report also identified some challenging charging behaviours that could cause network issues locally in the short-term should EV ownership clusters evolve that disproportionally affect individual transformers.
This could also potentially cause significant medium to longer term network issues, unless managed. This was evident as:
- Convenience home charging in the normal network residential evening peaks. Whilst seen to some degree in all owner groupings, there was more common with PHEV owners as well as those without direct access to their own solar generation.
- The impact of a significant pricing discount that caused a disproportionally large early morning hours peak in EV charging from approximately 13% of the participants. This was due to the price signal creating an accidental ‘peak’ due to all EVs in the area having their charge timers set to begin at the onset of the cheaper tariff.
Overall, the report summed up the findings as “EV charging is a very flexible load for management. Flexibility provides the ability to actively maximise diversity in energy use and demand, for both owner and network benefit. This allows for the creation of many charging options for EV owners that will also be network friendly”.
You may say that to some degree, this is a statement of the ‘bleeding obvious’ – EVs after all are not like air conditioners: you charge them when it is best to do so, not necessarily when you arrive home.
However, it is good to see the electricity providers recognising the need to offer tariffs and systems that are designed to spread the load in ways that suit the grid – and that EV owners are happy to use them.
It is also yet another data point to counter the EV naysayers that persist in pedalling the myth that ‘EVs will bring down the grid’.
The full report can be found at: https://www.energex.com.au/home/control-your-energy/smarter-energy/electric-vehicles/ev-insights
Bryce Gaton is an expert on electric vehicles and contributor for The Driven and Renew Economy. He has been working in the EV sector since 2008 and is currently working as EV electrical safety trainer/supervisor for the University of Melbourne. He also provides support for the EV Transition to business, government and the public through his EV Transition consultancy EVchoice.
