Ergon Readies Plan To Teach EV Owners How To Play Nice With The Grid

Charging electric vehicles and the impact on the mains grid

I’ve heard lots of predictions about electric vehicles’ role as storage in a renewable energy future. But it’s never before occurred to me that networks might encourage EV owners of the future to fill up their cars at a charging station during the daytime, specifically so they can use that electricity to power their home at night.

That’s a suggestion offered almost as an aside in an Ergon Energy paper setting out the network’s possible approaches to managing a network that has to keep Queensland’s future electric vehicle fleet on the road.

Here’s what Ergon Energy says in this report, its “Network EV Tactical Plan”:

“It is likely that a small but growing number of owners of V2G [vehicle-to-grid – SolarQuotes] capable EVs may seek to discharge energy from their EV to their building or home, and possibly even export it to the grid.


“In addition, some customers with V2G-capable EVs could be compelled to charge their vehicle at public charging stations, sometimes at no cost, and bring that energy home to power their house, potentially daily. This concept may even be more cost-effective than also investing in stationary batteries in the home”.

“Compelled”, yes! It seems that Ergon, worried about how to manage daytime over-voltage in a renewables-heavy grid, thinks it might be worth giving away excess electrons for electric vehicle owners to store and take home.

That’s pretty much an aside in the tactical plan, which centres on working out what a rising number of EVs might do to power networks, and what networks need to do to mitigate their potential impacts.

Behaviour Needs Management, Not Just Tech

It’s clear, as is so often the case, the soft sciences are going to be as important in managing the transition as technological implementations. It’s clear in the report that managing EV owner behaviour is a key part of managing network impacts.

EV owners pose a challenge for the grid because they don’t really know how their behaviour impacts the grid, and right now the incentives to charge in a grid-smart way are relatively new. Ergon and Energex both consider EVs in their Tariff Structure Statements published in July this year, and offers from AGL, Powershop and Ergon Energy Retail have only emerged since 2019.

As Ergon Energy notes in this discussion paper, most EV owners prioritise convenience and affordability, and their behaviours in general fall into “top-up” or “fill up”, oblivious to their impact on the network.

As electric vehicles multiply, both behaviours will pose issues for networks. Filling up the 100kWh capacity of a depleted Tesla Model S “consumes in a few hours as much electricity as an average household consumes in a week”, the paper noted. And attached to a 3-phase charger it can draw about four times as much power as the typical home – which offers a worrying future to the networks if a bunch of commuters need a fill-up during the evening peak.

Even those who favour top-up are a challenge: “the potential aggregated, coincidental impact (in both kW and kWh contexts) on the network of many EVs topping up and filling up could still be significant”, the report said.

Get Charging Away From Peaks

It’s unfair to sheet user behaviour down to cluelessness when the networks themselves are finding renewable energy integration hard to manage!

What’s needed is to align user behaviour with what the network needs:

“Our modelling indicates that a high penetration of EVs could be serviced by the existing network, provided most charging occurs at off-peak times in the longer term.”

Here are the ten tactics Ergon reckons will help:

  • Engage with EV salespeople, EV charger installers and owners about electric vehicle charging options;
  • Enhance the network connection process for both private and public EV charging stations;
  • Scope potential energy management opportunities presented by EVs;
  • Enable Vehicle-to-Grid (including Vehicle-to-Building) electric vehicle connections;
  • Implement mechanisms to identify EV charger locations;
  • Develop an EV data repository;
  • Deploy research into EV charging behaviours, network impacts and EV owner experiences;
  • Deploy a stakeholder engagement framework;
  • Establish network monitoring in areas of high EV penetration; and
  • Quantify the benefits to the network business of the customer adoption of electric vehicles.

We’re not going to go into detail on all ten of these – and after all, some, such as the networks’ need to know where there are high concentrations of EVs (and their battery capacity and charge rates) and a database of charger locations, are pretty obvious.

Ergon’s paper notes that currently, the EV owner gets very little of their information about charging from electric vehicle salespeople (who have a “generally low understanding … of the electricity tariff options for EV charging”). Rather, the customer gets referred to the EV charger installer for that information.

Ergon is hoping with the right engagement, EV sellers will help get tariff information in front of buyers so they choose tariffs that move electric vehicle charging away from peak demand period.

Related: The Homeowner’s Guide To Solar Power And Electric Cars

About Richard Chirgwin

Richard Chirgwin is a journalist with more than 30 years' experience covering a wide range of technology topics, including electronics, telecommunications, computing and science.


  1. Michael Paine says

    The big issue, I think, is going to be getting the electricity from the EV battery to the house. I have been investigating ways of powering 240V devices from an EV’s battery after finding out that, in the UK, the Mitsubishi Outlander PHEV has a 240VAC outlet in the cargo bay:
    This would be great for car-camping but no other EVs seem to have this feature. Playing around with ~400V EV batteries is not wise!

  2. Yes Minister says

    Ergon and Energex would need to do a lot of talking to convince me to play nice with them. We’ve endured decades of being ripped off by power barons intend on maximizing profits, shareholder dividends and executive bonuses and hence I am extremely suspicious of any proposition from these demonstrably avaricious organizations. For what its worth, I very rarely use grid power / dirty black electrons to fuel my EV as I have an abundance of clean green electrons from my off-grid PV system. To date, I have seen nothing even remotely attractive about vehicle to grid arrangements which in my opinion constitute yet another money-grab aimed at those gullible enough to get sucked in..

    • too true …… too true and they were allowed to get away with it. But in the end they ended up shooting themselves in the foot (actually both feet) because they ended up making the pay-back period to becoming energy independent so much swifter.

  3. Richard Kirby says

    I have been trying to charge my EV on a trickle charger basis (2kW) when the sun is out and my house solar is generating spare capacity. This is a fairly manual process and one that takes a little thought. However, doing so this way has little impact on the grid.

    What is needed are smarter systems. If my Tesla were plugged in can the software integrate with my solar system to know when spare power is available? If so it could trickle charger with spare. Far more cost effective for me than selling spare power to the grid or investing in batteries.

    • Have a look at Zappi

      They auto-adjust the charging rate to EV depending on available excess solar power much like the Solar Power Diverters do for hot water systems.

      • Richard Kirby says

        Thanks, will do.

      • Michael Paine says

        It looks like the Zappi is intended for pure EVs – it charges at up to 7kW and is quite expensive. Way too sophisticated for my needs. Also it is not clear from the UK website if it is compatible with a Tesla Powerwall system – especially the Gateway that provides backup power in the event of a grid blackout.
        In a separate discussion on this website I have pointed out the need for a low-cost 240V switch that can detect when excess solar power is being generated (or gets this information from systems like Powerwall).

        • Yes, there is such a device…. from

          A solar relay….

          Scroll down the page to download the brochure (after closing the never miss an update box).
          (link below to the brochure directly, not sure it will work but worth a try)

          It can be programmed to switch on the relay when a threshold is met.

          I think it’s about $250 and has been mentioned in another blog in Solarquotes

        • No, it supports PHEVs as well.

          Shouldn’t really matter what type of battery setup is used in BEV, EV, PHEVs or whatever they want to call cars with big batteries as a power source.

          • Michael Paine says

            Although the Zappi will work with PHEVs it doesn’t seem worthwhile charging a 10kWh battery in ~2 hours at 5kW but having to pay around $2000 to have the Zappi installed. I will be happy to charge it over 4 hours or so at under 2kW using a standard 240V outlet.
            I expect to do this during off-peak times but was interested in ways I could charge it from solar, but only when the excess would otherwise be feeding into the grid. So thank you to the others who have suggested some options.
            In any case I have a Powerwall 2 and it is suppose to learn our electricity consumption habits and adjust its charging and discharging to optimise use of solar and off-peak electricity. I threw it into a spin the other day when I programmed the Energy Australia summer peak times (2pm to 8pm!) into the app. It is still trying to adjust to the change. My point is that I will need to take the Powerwall activity into account in optimising EV/PHEV charging.

    • Dominic Wild says

      Michael Paine: The Fronius Symo with its inbuilt Datamanager soft- and hard ware can drive up to four relays in case of specified solar PRODUCTION, but not SURPLUS and I am going to use it for my H/W system.

      For surplus, it will need an extra gizmo at a cost of $600 or so.

      By the way, EV owners have been fined by their suppliers because their contract does not allow them to draw as much as four houses.

  4. Yet it appears Synergy (WA) has specifically discouraged V2G in its new DEBs scheme. While government monopolies view solar / V2G as a threat to their sacred cash-cows, West Aussies are unlikely to embrace these ‘new’ technologies.

    Instead, we’ll await new battery technologies, such as the MMB, which will enhance not only Powerwall longevity, but also warranties… then…

    …goodbye, Grid!

  5. I can see the future need, as electric vehicles become more mainstream for networks to require the installation of cut off facilities like they are considering for our home inverters or perhaps timers so they can isolate the massive charger consumption that there will be and leave the home powered perhaps or cut the lot off if the situation called for it for as you say they consume much more than the house.
    Depending on the cheapest option of upgrading the network which no one seems to want to do or installing remote switching via our smart meters to compulsory ensure charging at the best time.
    I think you will never get the majority arriving home in perilous conditions that might call for cuts with a near-flat battery from charging it in case they have to flee.

  6. Consuming excess solar and time of use charging needs to become mainstream. Zappos is good, but a workaround.

    These capabilities could be core to cars battery management systems and chargers alike, access via an API would accelerate adoption.

  7. Greg Wootten says

    Bought a Outlander PHEV with a distant promise of V2G but it keeps floating off into the future plus the price of existing V2G was about $10k so cheaper to buy a battery but still not viable economically
    Mitsubishi and Nissan both promise V2G, Nissan is close to offering a CSIRO system and Mitsubishi is close to offering a battery V2Home system called Dendo House but at what price. Both use the Japanese charger plug which is able to return power to an external transformer then to a home or grid.
    2 years ago the Spanish grid controllers saw the huge battery capacity of an electric car fleet as the way to have your car and electricity and balance
    Few cars will totally drain their batteries in a day so peak solar/wind and an intelligent charger based on grid price should enable a driver to plug in at work or home and set minimum charge levels they can tolerate and let the charger and network sort out supplying the grid or buying from the grid based on price
    This technology exists but does it talk to the rest of the system that’s what we need to fix. plus installing smart chargers everywhere they’re needed

    Tesla had V2G early on but are protective of their battery warranty so do not want owners to set it up on their vehicles. Conflict with their wall battery?

  8. This seems to be the big picture desirable outcome:
    Manage the duck curve and increase renewables to reduce carbon emissions so incentivise most charging to be done during the middle few hours of the day. This means getting lots of chargers into parking stations and in parking areas under city buildings.

    Everything else ought be done in pursuance of that overarching objective.

    Overnight charging using fossil fuels would be counter to sensible climate charge policy. Renewable power, whether from storage such as pumped hydro or batteries or from renewable power despatched at night (hydro, wind, wave) should be used for any charging at night.

  9. Michael Paine says

    I have been reading the owners manual for a Volvo XC40 Recharge (PHEV). The charging advice seems to discourage partial charging – in effect it says leave it plugged in until it is fully charged. This complicates the logistics of charging from home solar. Owners will need to allow about 4 hours for charging an “empty” 10kWh battery. So a system using a solar relay to start charging may not be good for battery life. Similarly splitting charging into early-hours off-peak and midday solar may not be the best strategy.
    This also has implications for V2G use (for which the Volvo is not equipped) and maybe that is why manufacturers seem to be holding back on this feature.
    On the other hand, I would have thought the PHEV battery technology is very similar to a Tesla Powerwall home battery, which charges and discharges frequently. And, of course, during normal driving the PHEV battery is working the same way.
    Interesting that the Recharge has a “pre-conditioning” function where the air-conditioner/heater can be programmed to start up several minutes before the car is to be driven and while the car is still plugged into 240V. I guess that is important in Sweden and maybe that influences the advice in the owners manual.

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